* Re: [PATCH net-next] net: netdev_alloc_skb() use build_skb()
From: Michael S. Tsirkin @ 2012-06-04 21:54 UTC (permalink / raw)
To: Eric Dumazet; +Cc: Willy Tarreau, David Miller, netdev
In-Reply-To: <1338839579.2760.1932.camel@edumazet-glaptop>
On Mon, Jun 04, 2012 at 09:52:59PM +0200, Eric Dumazet wrote:
> On Mon, 2012-06-04 at 22:43 +0300, Michael S. Tsirkin wrote:
> > On Mon, Jun 04, 2012 at 09:29:45PM +0200, Eric Dumazet wrote:
> > > On Mon, 2012-06-04 at 21:16 +0300, Michael S. Tsirkin wrote:
> > >
> > > > Yes but if a tcp socket then hangs on, on one of the fragments,
> > > > while the other has been freed, the whole page is still
> > > > never reused, right?
> > > >
> > > > Doesn't this mean truesize should be 4K?
> > > >
> > >
> > > Yes, or more exactly PAGE_SIZE, but then performance would really go
> > > down on machines with 64KB pages.
> > > Maybe we should make the whole frag
> > > head idea enabled only for PAGE_SIZE=4096.
> > >
> > > Not sure we want to track precise truesize, as the minimum truesize is
> > > SKB_DATA_ALIGN(length + NET_SKB_PAD) + SKB_DATA_ALIGN(sizeof(struct
> > > skb_shared_info)) (64 + 64 + 320) = 448
> > >
> > > Its not like buggy drivers that used truesize = length
> > >
> > >
> >
> > Interesting. But where's the threshold?
> >
>
> It all depends on the global limit you have on your machine.
>
> If you allow tcp memory to use 10% of ram, then a systematic x4 error
> would allow it to use 40% of ram. Mabe not enough to crash.
>
> Now you have to find a real workload able to hit this limit for real...
>
> But, if you "allow" a driver to claim a truesize of 1 (instead of 4096),
> you can reach the limit and OOM faster
>
> You know, even the current page stored for each socket (sk_sndmsg_page)
> can be a problem if you setup 1.000.000 tcp sockets. That can consume
> 4GB of ram (added to inode/sockets themselves)
> This is not really taken into account right now...
>
>
Yes but what bugs me if the box is not under memory pressure
this overestimation limits buffers for no real gain.
How about we teach tcp to use data_len for buffer
limits normally and switch to truesize when low on memory?
--
MST
^ permalink raw reply
* Re: [PATCH net-next] net: netdev_alloc_skb() use build_skb()
From: Michael S. Tsirkin @ 2012-06-04 21:20 UTC (permalink / raw)
To: Eric Dumazet; +Cc: Willy Tarreau, David Miller, netdev
In-Reply-To: <1338839812.2760.1939.camel@edumazet-glaptop>
On Mon, Jun 04, 2012 at 09:56:52PM +0200, Eric Dumazet wrote:
> On Mon, 2012-06-04 at 22:48 +0300, Michael S. Tsirkin wrote:
>
> > If I do this what will truesize be? 128, no?
>
> My example was not correct, since you must have enough room for the
> SKB_DATA_ALIGN(sizeof(struct skb_shared_info)) ( 320 bytes )
>
> So it would be 128 + 320 = 448
>
Ugh. I forgot about that. shinfo goes into the same page,
so we'll have to also make all frags shorter by 320
to leave space for shinfo at tail.
overall looks like we need hyprevisor extensions if
we want to use build_skb ...
^ permalink raw reply
* [PATCH v9] tilegx network driver: initial support
From: Chris Metcalf @ 2012-06-04 20:12 UTC (permalink / raw)
To: bhutchings, arnd, David Miller, linux-kernel, netdev
In-Reply-To: <201205251853.q4PIrE7T000723@lab-41.internal.tilera.com>
This change adds support for the tilegx network driver based on the
GXIO IORPC support in the tilegx software stack, using the on-chip
mPIPE packet processing engine.
Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>
---
This change fixes some bugs that were discovered during additional
testing of the TSO refactoring. In addition, I added a comment
explaining why we provide TSO support as essentially driver-side GSO.
The previous v8 version of the patch (from 10 days ago) received no
feedback; if anyone would care to provide feedback on this version of
the driver, it would be much appreciated. Thanks!
drivers/net/ethernet/tile/Kconfig | 2 +
drivers/net/ethernet/tile/Makefile | 4 +-
drivers/net/ethernet/tile/tilegx.c | 1875 ++++++++++++++++++++++++++++++++++++
3 files changed, 1879 insertions(+), 2 deletions(-)
create mode 100644 drivers/net/ethernet/tile/tilegx.c
diff --git a/drivers/net/ethernet/tile/Kconfig b/drivers/net/ethernet/tile/Kconfig
index 2d9218f..098b1c4 100644
--- a/drivers/net/ethernet/tile/Kconfig
+++ b/drivers/net/ethernet/tile/Kconfig
@@ -7,6 +7,8 @@ config TILE_NET
depends on TILE
default y
select CRC32
+ select TILE_GXIO_MPIPE if TILEGX
+ select HIGH_RES_TIMERS if TILEGX
---help---
This is a standard Linux network device driver for the
on-chip Tilera Gigabit Ethernet and XAUI interfaces.
diff --git a/drivers/net/ethernet/tile/Makefile b/drivers/net/ethernet/tile/Makefile
index f634f14..0ef9eef 100644
--- a/drivers/net/ethernet/tile/Makefile
+++ b/drivers/net/ethernet/tile/Makefile
@@ -4,7 +4,7 @@
obj-$(CONFIG_TILE_NET) += tile_net.o
ifdef CONFIG_TILEGX
-tile_net-objs := tilegx.o mpipe.o iorpc_mpipe.o dma_queue.o
+tile_net-y := tilegx.o
else
-tile_net-objs := tilepro.o
+tile_net-y := tilepro.o
endif
diff --git a/drivers/net/ethernet/tile/tilegx.c b/drivers/net/ethernet/tile/tilegx.c
new file mode 100644
index 0000000..a729499
--- /dev/null
+++ b/drivers/net/ethernet/tile/tilegx.c
@@ -0,0 +1,1875 @@
+/*
+ * Copyright 2012 Tilera Corporation. All Rights Reserved.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation, version 2.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
+ * NON INFRINGEMENT. See the GNU General Public License for
+ * more details.
+ */
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/moduleparam.h>
+#include <linux/sched.h>
+#include <linux/kernel.h> /* printk() */
+#include <linux/slab.h> /* kmalloc() */
+#include <linux/errno.h> /* error codes */
+#include <linux/types.h> /* size_t */
+#include <linux/interrupt.h>
+#include <linux/in.h>
+#include <linux/irq.h>
+#include <linux/netdevice.h> /* struct device, and other headers */
+#include <linux/etherdevice.h> /* eth_type_trans */
+#include <linux/skbuff.h>
+#include <linux/ioctl.h>
+#include <linux/cdev.h>
+#include <linux/hugetlb.h>
+#include <linux/in6.h>
+#include <linux/timer.h>
+#include <linux/hrtimer.h>
+#include <linux/ktime.h>
+#include <linux/io.h>
+#include <linux/ctype.h>
+#include <linux/ip.h>
+#include <linux/tcp.h>
+
+#include <asm/checksum.h>
+#include <asm/homecache.h>
+#include <gxio/mpipe.h>
+#include <arch/sim.h>
+
+/* Default transmit lockup timeout period, in jiffies. */
+#define TILE_NET_TIMEOUT (5 * HZ)
+
+/* The maximum number of distinct channels (idesc.channel is 5 bits). */
+#define TILE_NET_CHANNELS 32
+
+/* Maximum number of idescs to handle per "poll". */
+#define TILE_NET_BATCH 128
+
+/* Maximum number of packets to handle per "poll". */
+#define TILE_NET_WEIGHT 64
+
+/* Number of entries in each iqueue. */
+#define IQUEUE_ENTRIES 512
+
+/* Number of entries in each equeue. */
+#define EQUEUE_ENTRIES 2048
+
+/* Total header bytes per equeue slot. Must be big enough for 2 bytes
+ * of NET_IP_ALIGN alignment, plus 14 bytes (?) of L2 header, plus up to
+ * 60 bytes of actual TCP header. We round up to align to cache lines.
+ */
+#define HEADER_BYTES 128
+
+/* Maximum completions per cpu per device (must be a power of two).
+ * ISSUE: What is the right number here? If this is too small, then
+ * egress might block waiting for free space in a completions array.
+ * ISSUE: At the least, allocate these only for initialized echannels.
+ */
+#define TILE_NET_MAX_COMPS 64
+
+#define MAX_FRAGS (MAX_SKB_FRAGS + 1)
+
+/* Size of completions data to allocate.
+ * ISSUE: Probably more than needed since we don't use all the channels.
+ */
+#define COMPS_SIZE (TILE_NET_CHANNELS * sizeof(struct tile_net_comps))
+
+/* Size of NotifRing data to allocate. */
+#define NOTIF_RING_SIZE (IQUEUE_ENTRIES * sizeof(gxio_mpipe_idesc_t))
+
+/* Timeout to wake the per-device TX timer after we stop the queue.
+ * We don't want the timeout too short (adds overhead, and might end
+ * up causing stop/wake/stop/wake cycles) or too long (affects performance).
+ * For the 10 Gb NIC, 30 usec means roughly 30+ 1500-byte packets.
+ */
+#define TX_TIMER_DELAY_USEC 30
+
+/* Timeout to wake the per-cpu egress timer to free completions. */
+#define EGRESS_TIMER_DELAY_USEC 1000
+
+MODULE_AUTHOR("Tilera Corporation");
+MODULE_LICENSE("GPL");
+
+/* A "packet fragment" (a chunk of memory). */
+struct frag {
+ void *buf;
+ size_t length;
+};
+
+/* A single completion. */
+struct tile_net_comp {
+ /* The "complete_count" when the completion will be complete. */
+ s64 when;
+ /* The buffer to be freed when the completion is complete. */
+ struct sk_buff *skb;
+};
+
+/* The completions for a given cpu and device. */
+struct tile_net_comps {
+ /* The completions. */
+ struct tile_net_comp comp_queue[TILE_NET_MAX_COMPS];
+ /* The number of completions used. */
+ unsigned long comp_next;
+ /* The number of completions freed. */
+ unsigned long comp_last;
+};
+
+/* Info for a specific cpu. */
+struct tile_net_info {
+ /* The NAPI struct. */
+ struct napi_struct napi;
+ /* Packet queue. */
+ gxio_mpipe_iqueue_t iqueue;
+ /* Our cpu. */
+ int my_cpu;
+ /* True if iqueue is valid. */
+ bool has_iqueue;
+ /* NAPI flags. */
+ bool napi_added;
+ bool napi_enabled;
+ /* Number of small sk_buffs which must still be provided. */
+ unsigned int num_needed_small_buffers;
+ /* Number of large sk_buffs which must still be provided. */
+ unsigned int num_needed_large_buffers;
+ /* A timer for handling egress completions. */
+ struct hrtimer egress_timer;
+ /* True if "egress_timer" is scheduled. */
+ bool egress_timer_scheduled;
+ /* Comps for each egress channel. */
+ struct tile_net_comps *comps_for_echannel[TILE_NET_CHANNELS];
+};
+
+/* Info for egress on a particular egress channel. */
+struct tile_net_egress {
+ /* The "equeue". */
+ gxio_mpipe_equeue_t *equeue;
+ /* The headers for TSO. */
+ unsigned char *headers;
+};
+
+/* Info for a specific device. */
+struct tile_net_priv {
+ /* Our network device. */
+ struct net_device *dev;
+ /* The primary link. */
+ gxio_mpipe_link_t link;
+ /* The primary channel, if open, else -1. */
+ int channel;
+ /* The "loopify" egress link, if needed. */
+ gxio_mpipe_link_t loopify_link;
+ /* The "loopify" egress channel, if open, else -1. */
+ int loopify_channel;
+ /* The egress channel (channel or loopify_channel). */
+ int echannel;
+ /* Total stats. */
+ struct net_device_stats stats;
+ /* Timer to wake up tx queue */
+ struct hrtimer tx_wake_timer;
+};
+
+/* Egress info, indexed by "priv->echannel" (lazily created as needed). */
+static struct tile_net_egress egress_for_echannel[TILE_NET_CHANNELS];
+
+/* Devices currently associated with each channel.
+ * NOTE: The array entry can become NULL after ifconfig down, but
+ * we do not free the underlying net_device structures, so it is
+ * safe to use a pointer after reading it from this array.
+ */
+static struct net_device *tile_net_devs_for_channel[TILE_NET_CHANNELS];
+
+/* A mutex for "tile_net_devs_for_channel". */
+static DEFINE_MUTEX(tile_net_devs_for_channel_mutex);
+
+/* The per-cpu info. */
+static DEFINE_PER_CPU(struct tile_net_info, per_cpu_info);
+
+/* The "context" for all devices. */
+static gxio_mpipe_context_t context;
+
+/* The small/large "buffer stacks". */
+static int small_buffer_stack = -1;
+static int large_buffer_stack = -1;
+
+/* Amount of memory allocated for each buffer stack. */
+static size_t buffer_stack_size;
+
+/* The actual memory allocated for the buffer stacks. */
+static void *small_buffer_stack_va;
+static void *large_buffer_stack_va;
+
+/* The buckets. */
+static int first_bucket = -1;
+static int num_buckets = 1;
+
+/* The ingress irq. */
+static int ingress_irq = -1;
+
+/* Text value of tile_net.cpus if passed as a module parameter. */
+static char *network_cpus_string;
+
+/* The actual cpus in "network_cpus". */
+static struct cpumask network_cpus_map;
+
+/* If "loopify=LINK" was specified, this is "LINK". */
+static char *loopify_link_name;
+
+/* If "tile_net.custom" was specified, this is non-NULL. */
+static char *custom_str;
+
+/* The "tile_net.cpus" argument specifies the cpus that are dedicated
+ * to handle ingress packets.
+ *
+ * The parameter should be in the form "tile_net.cpus=m-n[,x-y]", where
+ * m, n, x, y are integer numbers that represent the cpus that can be
+ * neither a dedicated cpu nor a dataplane cpu.
+ */
+static bool network_cpus_init(void)
+{
+ char buf[1024];
+ int rc;
+
+ if (network_cpus_string == NULL)
+ return false;
+
+ rc = cpulist_parse_crop(network_cpus_string, &network_cpus_map);
+ if (rc != 0) {
+ pr_warn("tile_net.cpus=%s: malformed cpu list\n",
+ network_cpus_string);
+ return false;
+ }
+
+ /* Remove dedicated cpus. */
+ cpumask_and(&network_cpus_map, &network_cpus_map, cpu_possible_mask);
+
+ if (cpumask_empty(&network_cpus_map)) {
+ pr_warn("Ignoring empty tile_net.cpus='%s'.\n",
+ network_cpus_string);
+ return false;
+ }
+
+ cpulist_scnprintf(buf, sizeof(buf), &network_cpus_map);
+ pr_info("Linux network CPUs: %s\n", buf);
+ return true;
+}
+
+module_param_named(cpus, network_cpus_string, charp, 0444);
+MODULE_PARM_DESC(cpus, "cpulist of cores that handle network interrupts");
+
+/* The "tile_net.loopify=LINK" argument causes the named device to
+ * actually use "loop0" for ingress, and "loop1" for egress. This
+ * allows an app to sit between the actual link and linux, passing
+ * (some) packets along to linux, and forwarding (some) packets sent
+ * out by linux.
+ */
+module_param_named(loopify, loopify_link_name, charp, 0444);
+MODULE_PARM_DESC(loopify, "name the device to use loop0/1 for ingress/egress");
+
+/* The "tile_net.custom" argument causes us to ignore the "conventional"
+ * classifier metadata, in particular, the "l2_offset".
+ */
+module_param_named(custom, custom_str, charp, 0444);
+MODULE_PARM_DESC(custom, "indicates a (heavily) customized classifier");
+
+/* Atomically update a statistics field.
+ * Note that on TILE-Gx, this operation is fire-and-forget on the
+ * issuing core (single-cycle dispatch) and takes only a few cycles
+ * longer than a regular store when the request reaches the home cache.
+ * No expensive bus management overhead is required.
+ */
+static void tile_net_stats_add(unsigned long value, unsigned long *field)
+{
+ BUILD_BUG_ON(sizeof(atomic_long_t) != sizeof(unsigned long));
+ atomic_long_add(value, (atomic_long_t *)field);
+}
+
+/* Allocate and push a buffer. */
+static bool tile_net_provide_buffer(bool small)
+{
+ int stack = small ? small_buffer_stack : large_buffer_stack;
+ const unsigned long buffer_alignment = 128;
+ struct sk_buff *skb;
+ int len;
+
+ len = sizeof(struct sk_buff **) + buffer_alignment;
+ len += (small ? 128 : 1664);
+ skb = dev_alloc_skb(len);
+ if (skb == NULL)
+ return false;
+
+ /* Make room for a back-pointer to 'skb' and guarantee alignment. */
+ skb_reserve(skb, sizeof(struct sk_buff **));
+ skb_reserve(skb, -(long)skb->data & (buffer_alignment - 1));
+
+ /* Save a back-pointer to 'skb'. */
+ *(struct sk_buff **)(skb->data - sizeof(struct sk_buff **)) = skb;
+
+ /* Make sure "skb" and the back-pointer have been flushed. */
+ wmb();
+
+ gxio_mpipe_push_buffer(&context, stack,
+ (void *)va_to_tile_io_addr(skb->data));
+
+ return true;
+}
+
+/* Convert a raw mpipe buffer to its matching skb pointer. */
+static struct sk_buff *mpipe_buf_to_skb(void *va)
+{
+ /* Acquire the associated "skb". */
+ struct sk_buff **skb_ptr = va - sizeof(*skb_ptr);
+ struct sk_buff *skb = *skb_ptr;
+
+ /* Paranoia. */
+ if (skb->data != va) {
+ /* Panic here since there's a reasonable chance
+ * that corrupt buffers means generic memory
+ * corruption, with unpredictable system effects.
+ */
+ panic("Corrupt linux buffer! va=%p, skb=%p, skb->data=%p",
+ va, skb, skb->data);
+ }
+
+ return skb;
+}
+
+static void tile_net_pop_all_buffers(int stack)
+{
+ for (;;) {
+ tile_io_addr_t addr =
+ (tile_io_addr_t)gxio_mpipe_pop_buffer(&context, stack);
+ if (addr == 0)
+ break;
+ dev_kfree_skb_irq(mpipe_buf_to_skb(tile_io_addr_to_va(addr)));
+ }
+}
+
+/* Provide linux buffers to mPIPE. */
+static void tile_net_provide_needed_buffers(struct tile_net_info *info)
+{
+ while (info->num_needed_small_buffers != 0) {
+ if (!tile_net_provide_buffer(true))
+ goto oops;
+ info->num_needed_small_buffers--;
+ }
+
+ while (info->num_needed_large_buffers != 0) {
+ if (!tile_net_provide_buffer(false))
+ goto oops;
+ info->num_needed_large_buffers--;
+ }
+
+ return;
+
+oops:
+ /* Add a description to the page allocation failure dump. */
+ pr_notice("Tile %d still needs some buffers\n", info->my_cpu);
+}
+
+static inline bool filter_packet(struct net_device *dev, void *buf)
+{
+ /* Filter packets received before we're up. */
+ if (dev == NULL || !(dev->flags & IFF_UP))
+ return true;
+
+ /* Filter out packets that aren't for us. */
+ if (!(dev->flags & IFF_PROMISC) &&
+ !is_multicast_ether_addr(buf) &&
+ compare_ether_addr(dev->dev_addr, buf) != 0)
+ return true;
+
+ return false;
+}
+
+static void tile_net_receive_skb(struct net_device *dev, struct sk_buff *skb,
+ struct tile_net_info *info,
+ gxio_mpipe_idesc_t *idesc, unsigned long len)
+{
+ struct tile_net_priv *priv = netdev_priv(dev);
+
+ /* Encode the actual packet length. */
+ skb_put(skb, len);
+
+ skb->protocol = eth_type_trans(skb, dev);
+
+ /* Acknowledge "good" hardware checksums. */
+ if (idesc->cs && idesc->csum_seed_val == 0xFFFF)
+ skb->ip_summed = CHECKSUM_UNNECESSARY;
+
+ netif_receive_skb(skb);
+
+ /* Update stats. */
+ tile_net_stats_add(1, &priv->stats.rx_packets);
+ tile_net_stats_add(len, &priv->stats.rx_bytes);
+
+ /* Need a new buffer. */
+ if (idesc->size == GXIO_MPIPE_BUFFER_SIZE_128)
+ info->num_needed_small_buffers++;
+ else
+ info->num_needed_large_buffers++;
+}
+
+/* Handle a packet. Return true if "processed", false if "filtered". */
+static bool tile_net_handle_packet(struct tile_net_info *info,
+ gxio_mpipe_idesc_t *idesc)
+{
+ struct net_device *dev = tile_net_devs_for_channel[idesc->channel];
+ uint8_t l2_offset;
+ void *va;
+ void *buf;
+ unsigned long len;
+ bool filter;
+
+ /* Drop packets for which no buffer was available.
+ * NOTE: This happens under heavy load.
+ */
+ if (idesc->be) {
+ struct tile_net_priv *priv = netdev_priv(dev);
+ tile_net_stats_add(1, &priv->stats.rx_dropped);
+ gxio_mpipe_iqueue_consume(&info->iqueue, idesc);
+ if (net_ratelimit())
+ pr_info("Dropping packet (insufficient buffers).\n");
+ return false;
+ }
+
+ /* Get the "l2_offset", if allowed. */
+ l2_offset = custom_str ? 0 : gxio_mpipe_idesc_get_l2_offset(idesc);
+
+ /* Get the raw buffer VA (includes "headroom"). */
+ va = tile_io_addr_to_va((unsigned long)(long)idesc->va);
+
+ /* Get the actual packet start/length. */
+ buf = va + l2_offset;
+ len = idesc->l2_size - l2_offset;
+
+ /* Point "va" at the raw buffer. */
+ va -= NET_IP_ALIGN;
+
+ filter = filter_packet(dev, buf);
+ if (filter) {
+ gxio_mpipe_iqueue_drop(&info->iqueue, idesc);
+ } else {
+ struct sk_buff *skb = mpipe_buf_to_skb(va);
+
+ /* Skip headroom, and any custom header. */
+ skb_reserve(skb, NET_IP_ALIGN + l2_offset);
+
+ tile_net_receive_skb(dev, skb, info, idesc, len);
+ }
+
+ gxio_mpipe_iqueue_consume(&info->iqueue, idesc);
+ return !filter;
+}
+
+/* Handle some packets for the current CPU.
+ *
+ * This function handles up to TILE_NET_BATCH idescs per call.
+ *
+ * ISSUE: Since we do not provide new buffers until this function is
+ * complete, we must initially provide enough buffers for each network
+ * cpu to fill its iqueue and also its batched idescs.
+ *
+ * ISSUE: The "rotting packet" race condition occurs if a packet
+ * arrives after the queue appears to be empty, and before the
+ * hypervisor interrupt is re-enabled.
+ */
+static int tile_net_poll(struct napi_struct *napi, int budget)
+{
+ struct tile_net_info *info = &__get_cpu_var(per_cpu_info);
+ unsigned int work = 0;
+ gxio_mpipe_idesc_t *idesc;
+ int i, n;
+
+ /* Process packets. */
+ while ((n = gxio_mpipe_iqueue_try_peek(&info->iqueue, &idesc)) > 0) {
+ for (i = 0; i < n; i++) {
+ if (i == TILE_NET_BATCH)
+ goto done;
+ if (tile_net_handle_packet(info, idesc + i)) {
+ if (++work >= budget)
+ goto done;
+ }
+ }
+ }
+
+ /* There are no packets left. */
+ napi_complete(&info->napi);
+
+ /* Re-enable hypervisor interrupts. */
+ gxio_mpipe_enable_notif_ring_interrupt(&context, info->iqueue.ring);
+
+ /* HACK: Avoid the "rotting packet" problem. */
+ if (gxio_mpipe_iqueue_try_peek(&info->iqueue, &idesc) > 0)
+ napi_schedule(&info->napi);
+
+ /* ISSUE: Handle completions? */
+
+done:
+ tile_net_provide_needed_buffers(info);
+
+ return work;
+}
+
+/* Handle an ingress interrupt on the current cpu. */
+static irqreturn_t tile_net_handle_ingress_irq(int irq, void *unused)
+{
+ struct tile_net_info *info = &__get_cpu_var(per_cpu_info);
+ napi_schedule(&info->napi);
+ return IRQ_HANDLED;
+}
+
+/* Free some completions. This must be called with interrupts blocked. */
+static int tile_net_free_comps(gxio_mpipe_equeue_t *equeue,
+ struct tile_net_comps *comps,
+ int limit, bool force_update)
+{
+ int n = 0;
+ while (comps->comp_last < comps->comp_next) {
+ unsigned int cid = comps->comp_last % TILE_NET_MAX_COMPS;
+ struct tile_net_comp *comp = &comps->comp_queue[cid];
+ if (!gxio_mpipe_equeue_is_complete(equeue, comp->when,
+ force_update || n == 0))
+ break;
+ dev_kfree_skb_irq(comp->skb);
+ comps->comp_last++;
+ if (++n == limit)
+ break;
+ }
+ return n;
+}
+
+/* Add a completion. This must be called with interrupts blocked.
+ * tile_net_equeue_try_reserve() will have ensured a free completion entry.
+ */
+static void add_comp(gxio_mpipe_equeue_t *equeue,
+ struct tile_net_comps *comps,
+ uint64_t when, struct sk_buff *skb)
+{
+ int cid = comps->comp_next % TILE_NET_MAX_COMPS;
+ comps->comp_queue[cid].when = when;
+ comps->comp_queue[cid].skb = skb;
+ comps->comp_next++;
+}
+
+static void tile_net_schedule_tx_wake_timer(struct net_device *dev)
+{
+ struct tile_net_priv *priv = netdev_priv(dev);
+
+ hrtimer_start(&priv->tx_wake_timer,
+ ktime_set(0, TX_TIMER_DELAY_USEC * 1000UL),
+ HRTIMER_MODE_REL);
+}
+
+static enum hrtimer_restart tile_net_handle_tx_wake_timer(struct hrtimer *t)
+{
+ struct net_device *dev;
+ struct tile_net_priv *priv;
+
+ priv = container_of(t, struct tile_net_priv, tx_wake_timer);
+ dev = priv->dev;
+
+ if (netif_queue_stopped(dev))
+ netif_wake_queue(dev);
+
+ return HRTIMER_NORESTART;
+}
+
+/* Make sure the egress timer is scheduled.
+ *
+ * Note that we use "schedule if not scheduled" logic instead of the more
+ * obvious "reschedule" logic, because "reschedule" is fairly expensive.
+ */
+static void tile_net_schedule_egress_timer(struct tile_net_info *info)
+{
+ if (!info->egress_timer_scheduled) {
+ hrtimer_start(&info->egress_timer,
+ ktime_set(0, EGRESS_TIMER_DELAY_USEC * 1000UL),
+ HRTIMER_MODE_REL_PINNED);
+ info->egress_timer_scheduled = true;
+ }
+}
+
+/* The "function" for "info->egress_timer".
+ *
+ * This timer will reschedule itself as long as there are any pending
+ * completions expected for this tile.
+ */
+static enum hrtimer_restart tile_net_handle_egress_timer(struct hrtimer *t)
+{
+ struct tile_net_info *info = &__get_cpu_var(per_cpu_info);
+ unsigned long irqflags;
+ bool pending = false;
+ int i;
+
+ local_irq_save(irqflags);
+
+ /* The timer is no longer scheduled. */
+ info->egress_timer_scheduled = false;
+
+ /* Free all possible comps for this tile. */
+ for (i = 0; i < TILE_NET_CHANNELS; i++) {
+ struct tile_net_egress *egress = &egress_for_echannel[i];
+ struct tile_net_comps *comps = info->comps_for_echannel[i];
+ if (comps->comp_last >= comps->comp_next)
+ continue;
+ tile_net_free_comps(egress->equeue, comps, -1, true);
+ pending = pending || (comps->comp_last < comps->comp_next);
+ }
+
+ /* Reschedule timer if needed. */
+ if (pending)
+ tile_net_schedule_egress_timer(info);
+
+ local_irq_restore(irqflags);
+
+ return HRTIMER_NORESTART;
+}
+
+/* Helper function for "tile_net_update()".
+ * "dev" (i.e. arg) is the device being brought up or down,
+ * or NULL if all devices are now down.
+ */
+static void tile_net_update_cpu(void *arg)
+{
+ struct net_device *dev = arg;
+ struct tile_net_info *info = &__get_cpu_var(per_cpu_info);
+
+ if (!info->has_iqueue)
+ return;
+
+ if (dev != NULL) {
+ if (!info->napi_added) {
+ netif_napi_add(dev, &info->napi,
+ tile_net_poll, TILE_NET_WEIGHT);
+ info->napi_added = true;
+ }
+ if (!info->napi_enabled) {
+ napi_enable(&info->napi);
+ info->napi_enabled = true;
+ }
+ enable_percpu_irq(ingress_irq, 0);
+ } else {
+ disable_percpu_irq(ingress_irq);
+ if (info->napi_enabled) {
+ napi_disable(&info->napi);
+ info->napi_enabled = false;
+ }
+ /* FIXME: Drain the iqueue. */
+ }
+}
+
+/* Helper function for tile_net_open() and tile_net_stop().
+ * Always called under tile_net_devs_for_channel_mutex.
+ */
+static int tile_net_update(struct net_device *dev)
+{
+ static gxio_mpipe_rules_t rules; /* too big to fit on the stack */
+ bool saw_channel = false;
+ int channel;
+ int rc;
+ int cpu;
+
+ gxio_mpipe_rules_init(&rules, &context);
+
+ for (channel = 0; channel < TILE_NET_CHANNELS; channel++) {
+ if (tile_net_devs_for_channel[channel] == NULL)
+ continue;
+ if (!saw_channel) {
+ saw_channel = true;
+ gxio_mpipe_rules_begin(&rules, first_bucket,
+ num_buckets, NULL);
+ gxio_mpipe_rules_set_headroom(&rules, NET_IP_ALIGN);
+ }
+ gxio_mpipe_rules_add_channel(&rules, channel);
+ }
+
+ /* NOTE: This can fail if there is no classifier.
+ * ISSUE: Can anything else cause it to fail?
+ */
+ rc = gxio_mpipe_rules_commit(&rules);
+ if (rc != 0) {
+ netdev_warn(dev, "gxio_mpipe_rules_commit failed: %d\n", rc);
+ return -EIO;
+ }
+
+ /* Update all cpus, sequentially (to protect "netif_napi_add()"). */
+ for_each_online_cpu(cpu)
+ smp_call_function_single(cpu, tile_net_update_cpu,
+ (saw_channel ? dev : NULL), 1);
+
+ /* HACK: Allow packets to flow in the simulator. */
+ if (saw_channel)
+ sim_enable_mpipe_links(0, -1);
+
+ return 0;
+}
+
+/* Allocate and initialize mpipe buffer stacks, and register them in
+ * the mPIPE TLBs, for both small and large packet sizes.
+ * This routine supports tile_net_init_mpipe(), below.
+ */
+static int init_buffer_stacks(struct net_device *dev, int num_buffers)
+{
+ pte_t hash_pte = pte_set_home((pte_t) { 0 }, PAGE_HOME_HASH);
+ int rc;
+
+ /* Compute stack bytes; we round up to 64KB and then use
+ * alloc_pages() so we get the required 64KB alignment as well.
+ */
+ buffer_stack_size =
+ ALIGN(gxio_mpipe_calc_buffer_stack_bytes(num_buffers),
+ 64 * 1024);
+
+ /* Allocate two buffer stack indices. */
+ rc = gxio_mpipe_alloc_buffer_stacks(&context, 2, 0, 0);
+ if (rc < 0) {
+ netdev_err(dev, "gxio_mpipe_alloc_buffer_stacks failed: %d\n",
+ rc);
+ return rc;
+ }
+ small_buffer_stack = rc;
+ large_buffer_stack = rc + 1;
+
+ /* Allocate the small memory stack. */
+ small_buffer_stack_va =
+ alloc_pages_exact(buffer_stack_size, GFP_KERNEL);
+ if (small_buffer_stack_va == NULL) {
+ netdev_err(dev,
+ "Could not alloc %zd bytes for buffer stacks\n",
+ buffer_stack_size);
+ return -ENOMEM;
+ }
+ rc = gxio_mpipe_init_buffer_stack(&context, small_buffer_stack,
+ GXIO_MPIPE_BUFFER_SIZE_128,
+ small_buffer_stack_va,
+ buffer_stack_size, 0);
+ if (rc != 0) {
+ netdev_err(dev, "gxio_mpipe_init_buffer_stack: %d\n", rc);
+ return rc;
+ }
+ rc = gxio_mpipe_register_client_memory(&context, small_buffer_stack,
+ hash_pte, 0);
+ if (rc != 0) {
+ netdev_err(dev,
+ "gxio_mpipe_register_buffer_memory failed: %d\n",
+ rc);
+ return rc;
+ }
+
+ /* Allocate the large buffer stack. */
+ large_buffer_stack_va =
+ alloc_pages_exact(buffer_stack_size, GFP_KERNEL);
+ if (large_buffer_stack_va == NULL) {
+ netdev_err(dev,
+ "Could not alloc %zd bytes for buffer stacks\n",
+ buffer_stack_size);
+ return -ENOMEM;
+ }
+ rc = gxio_mpipe_init_buffer_stack(&context, large_buffer_stack,
+ GXIO_MPIPE_BUFFER_SIZE_1664,
+ large_buffer_stack_va,
+ buffer_stack_size, 0);
+ if (rc != 0) {
+ netdev_err(dev, "gxio_mpipe_init_buffer_stack failed: %d\n",
+ rc);
+ return rc;
+ }
+ rc = gxio_mpipe_register_client_memory(&context, large_buffer_stack,
+ hash_pte, 0);
+ if (rc != 0) {
+ netdev_err(dev,
+ "gxio_mpipe_register_buffer_memory failed: %d\n",
+ rc);
+ return rc;
+ }
+
+ return 0;
+}
+
+/* Allocate per-cpu resources (memory for completions and idescs).
+ * This routine supports tile_net_init_mpipe(), below.
+ */
+static int alloc_percpu_mpipe_resources(struct net_device *dev,
+ int cpu, int ring)
+{
+ struct tile_net_info *info = &per_cpu(per_cpu_info, cpu);
+ int order, i, rc;
+ struct page *page;
+ void *addr;
+
+ /* Allocate the "comps". */
+ order = get_order(COMPS_SIZE);
+ page = homecache_alloc_pages(GFP_KERNEL, order, cpu);
+ if (page == NULL) {
+ netdev_err(dev, "Failed to alloc %zd bytes comps memory\n",
+ COMPS_SIZE);
+ return -ENOMEM;
+ }
+ addr = pfn_to_kaddr(page_to_pfn(page));
+ memset(addr, 0, COMPS_SIZE);
+ for (i = 0; i < TILE_NET_CHANNELS; i++)
+ info->comps_for_echannel[i] =
+ addr + i * sizeof(struct tile_net_comps);
+
+ /* If this is a network cpu, create an iqueue. */
+ if (cpu_isset(cpu, network_cpus_map)) {
+ order = get_order(NOTIF_RING_SIZE);
+ page = homecache_alloc_pages(GFP_KERNEL, order, cpu);
+ if (page == NULL) {
+ netdev_err(dev,
+ "Failed to alloc %zd bytes iqueue memory\n",
+ NOTIF_RING_SIZE);
+ return -ENOMEM;
+ }
+ addr = pfn_to_kaddr(page_to_pfn(page));
+ rc = gxio_mpipe_iqueue_init(&info->iqueue, &context, ring++,
+ addr, NOTIF_RING_SIZE, 0);
+ if (rc < 0) {
+ netdev_err(dev,
+ "gxio_mpipe_iqueue_init failed: %d\n", rc);
+ return rc;
+ }
+ info->has_iqueue = true;
+ }
+
+ return ring;
+}
+
+/* Initialize NotifGroup and buckets.
+ * This routine supports tile_net_init_mpipe(), below.
+ */
+static int init_notif_group_and_buckets(struct net_device *dev,
+ int ring, int network_cpus_count)
+{
+ int group, rc;
+
+ /* Allocate one NotifGroup. */
+ rc = gxio_mpipe_alloc_notif_groups(&context, 1, 0, 0);
+ if (rc < 0) {
+ netdev_err(dev, "gxio_mpipe_alloc_notif_groups failed: %d\n",
+ rc);
+ return rc;
+ }
+ group = rc;
+
+ /* Initialize global num_buckets value. */
+ if (network_cpus_count > 4)
+ num_buckets = 256;
+ else if (network_cpus_count > 1)
+ num_buckets = 16;
+
+ /* Allocate some buckets, and set global first_bucket value. */
+ rc = gxio_mpipe_alloc_buckets(&context, num_buckets, 0, 0);
+ if (rc < 0) {
+ netdev_err(dev, "gxio_mpipe_alloc_buckets failed: %d\n", rc);
+ return rc;
+ }
+ first_bucket = rc;
+
+ /* Init group and buckets. */
+ rc = gxio_mpipe_init_notif_group_and_buckets(
+ &context, group, ring, network_cpus_count,
+ first_bucket, num_buckets,
+ GXIO_MPIPE_BUCKET_STICKY_FLOW_LOCALITY);
+ if (rc != 0) {
+ netdev_err(
+ dev,
+ "gxio_mpipe_init_notif_group_and_buckets failed: %d\n",
+ rc);
+ return rc;
+ }
+
+ return 0;
+}
+
+/* Create an irq and register it, then activate the irq and request
+ * interrupts on all cores. Note that "ingress_irq" being initialized
+ * is how we know not to call tile_net_init_mpipe() again.
+ * This routine supports tile_net_init_mpipe(), below.
+ */
+static int tile_net_setup_interrupts(struct net_device *dev)
+{
+ int cpu, rc;
+
+ rc = create_irq();
+ if (rc < 0) {
+ netdev_err(dev, "create_irq failed: %d\n", rc);
+ return rc;
+ }
+ ingress_irq = rc;
+ tile_irq_activate(ingress_irq, TILE_IRQ_PERCPU);
+ rc = request_irq(ingress_irq, tile_net_handle_ingress_irq,
+ 0, NULL, NULL);
+ if (rc != 0) {
+ netdev_err(dev, "request_irq failed: %d\n", rc);
+ destroy_irq(ingress_irq);
+ ingress_irq = -1;
+ return rc;
+ }
+
+ for_each_online_cpu(cpu) {
+ struct tile_net_info *info = &per_cpu(per_cpu_info, cpu);
+ if (info->has_iqueue) {
+ gxio_mpipe_request_notif_ring_interrupt(
+ &context, cpu_x(cpu), cpu_y(cpu),
+ 1, ingress_irq, info->iqueue.ring);
+ }
+ }
+
+ return 0;
+}
+
+/* Undo any state set up partially by a failed call to tile_net_init_mpipe. */
+static void tile_net_init_mpipe_fail(void)
+{
+ int cpu;
+
+ /* Do cleanups that require the mpipe context first. */
+ if (small_buffer_stack >= 0)
+ tile_net_pop_all_buffers(small_buffer_stack);
+ if (large_buffer_stack >= 0)
+ tile_net_pop_all_buffers(large_buffer_stack);
+
+ /* Destroy mpipe context so the hardware no longer owns any memory. */
+ gxio_mpipe_destroy(&context);
+
+ for_each_online_cpu(cpu) {
+ struct tile_net_info *info = &per_cpu(per_cpu_info, cpu);
+ free_pages((unsigned long)(info->comps_for_echannel[0]),
+ get_order(COMPS_SIZE));
+ info->comps_for_echannel[0] = NULL;
+ free_pages((unsigned long)(info->iqueue.idescs),
+ get_order(NOTIF_RING_SIZE));
+ info->iqueue.idescs = NULL;
+ }
+
+ if (small_buffer_stack_va)
+ free_pages_exact(small_buffer_stack_va, buffer_stack_size);
+ if (large_buffer_stack_va)
+ free_pages_exact(large_buffer_stack_va, buffer_stack_size);
+
+ small_buffer_stack_va = NULL;
+ large_buffer_stack_va = NULL;
+ large_buffer_stack = -1;
+ small_buffer_stack = -1;
+ first_bucket = -1;
+}
+
+/* The first time any tilegx network device is opened, we initialize
+ * the global mpipe state. If this step fails, we fail to open the
+ * device, but if it succeeds, we never need to do it again, and since
+ * tile_net can't be unloaded, we never undo it.
+ *
+ * Note that some resources in this path (buffer stack indices,
+ * bindings from init_buffer_stack, etc.) are hypervisor resources
+ * that are freed implicitly by gxio_mpipe_destroy().
+ */
+static int tile_net_init_mpipe(struct net_device *dev)
+{
+ int i, num_buffers, rc;
+ int cpu;
+ int first_ring, ring;
+ int network_cpus_count = cpus_weight(network_cpus_map);
+
+ if (!hash_default) {
+ netdev_err(dev, "Networking requires hash_default!\n");
+ return -EIO;
+ }
+
+ rc = gxio_mpipe_init(&context, 0);
+ if (rc != 0) {
+ netdev_err(dev, "gxio_mpipe_init failed: %d\n", rc);
+ return -EIO;
+ }
+
+ /* Set up the buffer stacks. */
+ num_buffers =
+ network_cpus_count * (IQUEUE_ENTRIES + TILE_NET_BATCH);
+ rc = init_buffer_stacks(dev, num_buffers);
+ if (rc != 0)
+ goto fail;
+
+ /* Provide initial buffers. */
+ rc = -ENOMEM;
+ for (i = 0; i < num_buffers; i++) {
+ if (!tile_net_provide_buffer(true)) {
+ netdev_err(dev, "Cannot allocate initial sk_bufs!\n");
+ goto fail;
+ }
+ }
+ for (i = 0; i < num_buffers; i++) {
+ if (!tile_net_provide_buffer(false)) {
+ netdev_err(dev, "Cannot allocate initial sk_bufs!\n");
+ goto fail;
+ }
+ }
+
+ /* Allocate one NotifRing for each network cpu. */
+ rc = gxio_mpipe_alloc_notif_rings(&context, network_cpus_count, 0, 0);
+ if (rc < 0) {
+ netdev_err(dev, "gxio_mpipe_alloc_notif_rings failed %d\n",
+ rc);
+ goto fail;
+ }
+
+ /* Init NotifRings per-cpu. */
+ first_ring = rc;
+ ring = first_ring;
+ for_each_online_cpu(cpu) {
+ rc = alloc_percpu_mpipe_resources(dev, cpu, ring);
+ if (rc < 0)
+ goto fail;
+ ring = rc;
+ }
+
+ /* Initialize NotifGroup and buckets. */
+ rc = init_notif_group_and_buckets(dev, first_ring, network_cpus_count);
+ if (rc != 0)
+ goto fail;
+
+ /* Create and enable interrupts. */
+ rc = tile_net_setup_interrupts(dev);
+ if (rc != 0)
+ goto fail;
+
+ return 0;
+
+fail:
+ tile_net_init_mpipe_fail();
+ return rc;
+}
+
+/* Create persistent egress info for a given egress channel.
+ * Note that this may be shared between, say, "gbe0" and "xgbe0".
+ * ISSUE: Defer header allocation until TSO is actually needed?
+ */
+static int tile_net_init_egress(struct net_device *dev, int echannel)
+{
+ struct page *headers_page, *edescs_page, *equeue_page;
+ gxio_mpipe_edesc_t *edescs;
+ gxio_mpipe_equeue_t *equeue;
+ unsigned char *headers;
+ int headers_order, edescs_order, equeue_order;
+ size_t edescs_size;
+ int edma;
+ int rc = -ENOMEM;
+
+ /* Only initialize once. */
+ if (egress_for_echannel[echannel].equeue != NULL)
+ return 0;
+
+ /* Allocate memory for the "headers". */
+ headers_order = get_order(EQUEUE_ENTRIES * HEADER_BYTES);
+ headers_page = alloc_pages(GFP_KERNEL, headers_order);
+ if (headers_page == NULL) {
+ netdev_warn(dev,
+ "Could not alloc %zd bytes for TSO headers.\n",
+ PAGE_SIZE << headers_order);
+ goto fail;
+ }
+ headers = pfn_to_kaddr(page_to_pfn(headers_page));
+
+ /* Allocate memory for the "edescs". */
+ edescs_size = EQUEUE_ENTRIES * sizeof(*edescs);
+ edescs_order = get_order(edescs_size);
+ edescs_page = alloc_pages(GFP_KERNEL, edescs_order);
+ if (edescs_page == NULL) {
+ netdev_warn(dev,
+ "Could not alloc %zd bytes for eDMA ring.\n",
+ edescs_size);
+ goto fail_headers;
+ }
+ edescs = pfn_to_kaddr(page_to_pfn(edescs_page));
+
+ /* Allocate memory for the "equeue". */
+ equeue_order = get_order(sizeof(*equeue));
+ equeue_page = alloc_pages(GFP_KERNEL, equeue_order);
+ if (equeue_page == NULL) {
+ netdev_warn(dev,
+ "Could not alloc %zd bytes for equeue info.\n",
+ PAGE_SIZE << equeue_order);
+ goto fail_edescs;
+ }
+ equeue = pfn_to_kaddr(page_to_pfn(equeue_page));
+
+ /* Allocate an edma ring. Note that in practice this can't
+ * fail, which is good, because we will leak an edma ring if so.
+ */
+ rc = gxio_mpipe_alloc_edma_rings(&context, 1, 0, 0);
+ if (rc < 0) {
+ netdev_warn(dev, "gxio_mpipe_alloc_edma_rings failed: %d\n",
+ rc);
+ goto fail_equeue;
+ }
+ edma = rc;
+
+ /* Initialize the equeue. */
+ rc = gxio_mpipe_equeue_init(equeue, &context, edma, echannel,
+ edescs, edescs_size, 0);
+ if (rc != 0) {
+ netdev_err(dev, "gxio_mpipe_equeue_init failed: %d\n", rc);
+ goto fail_equeue;
+ }
+
+ /* Done. */
+ egress_for_echannel[echannel].equeue = equeue;
+ egress_for_echannel[echannel].headers = headers;
+ return 0;
+
+fail_equeue:
+ __free_pages(equeue_page, equeue_order);
+
+fail_edescs:
+ __free_pages(edescs_page, edescs_order);
+
+fail_headers:
+ __free_pages(headers_page, headers_order);
+
+fail:
+ return rc;
+}
+
+/* Return channel number for a newly-opened link. */
+static int tile_net_link_open(struct net_device *dev, gxio_mpipe_link_t *link,
+ const char *link_name)
+{
+ int rc = gxio_mpipe_link_open(link, &context, link_name, 0);
+ if (rc < 0) {
+ netdev_err(dev, "Failed to open '%s'\n", link_name);
+ return rc;
+ }
+ rc = gxio_mpipe_link_channel(link);
+ if (rc < 0 || rc >= TILE_NET_CHANNELS) {
+ netdev_err(dev, "gxio_mpipe_link_channel bad value: %d\n", rc);
+ gxio_mpipe_link_close(link);
+ return -EINVAL;
+ }
+ return rc;
+}
+
+/* Help the kernel activate the given network interface. */
+static int tile_net_open(struct net_device *dev)
+{
+ struct tile_net_priv *priv = netdev_priv(dev);
+ int rc;
+
+ mutex_lock(&tile_net_devs_for_channel_mutex);
+
+ /* Do one-time initialization the first time any device is opened. */
+ if (ingress_irq < 0) {
+ rc = tile_net_init_mpipe(dev);
+ if (rc != 0)
+ goto fail;
+ }
+
+ /* Determine if this is the "loopify" device. */
+ if (unlikely((loopify_link_name != NULL) &&
+ !strcmp(dev->name, loopify_link_name))) {
+ rc = tile_net_link_open(dev, &priv->link, "loop0");
+ if (rc < 0)
+ goto fail;
+ priv->channel = rc;
+ rc = tile_net_link_open(dev, &priv->loopify_link, "loop1");
+ if (rc < 0)
+ goto fail;
+ priv->loopify_channel = rc;
+ priv->echannel = rc;
+ } else {
+ rc = tile_net_link_open(dev, &priv->link, dev->name);
+ if (rc < 0)
+ goto fail;
+ priv->channel = rc;
+ priv->echannel = rc;
+ }
+
+ /* Initialize egress info (if needed). Once ever, per echannel. */
+ rc = tile_net_init_egress(dev, priv->echannel);
+ if (rc != 0)
+ goto fail;
+
+ tile_net_devs_for_channel[priv->channel] = dev;
+
+ rc = tile_net_update(dev);
+ if (rc != 0)
+ goto fail;
+
+ mutex_unlock(&tile_net_devs_for_channel_mutex);
+
+ netif_start_queue(dev);
+ netif_carrier_on(dev);
+ return 0;
+
+fail:
+ if (priv->loopify_channel >= 0) {
+ if (gxio_mpipe_link_close(&priv->loopify_link) != 0)
+ netdev_warn(dev, "Failed to close loopify link!\n");
+ priv->loopify_channel = -1;
+ }
+ if (priv->channel >= 0) {
+ if (gxio_mpipe_link_close(&priv->link) != 0)
+ netdev_warn(dev, "Failed to close link!\n");
+ priv->channel = -1;
+ }
+ priv->echannel = -1;
+ tile_net_devs_for_channel[priv->channel] = NULL;
+ mutex_unlock(&tile_net_devs_for_channel_mutex);
+
+ /* Don't return raw gxio error codes to generic Linux. */
+ return (rc > -512) ? rc : -EIO;
+}
+
+/* Help the kernel deactivate the given network interface. */
+static int tile_net_stop(struct net_device *dev)
+{
+ struct tile_net_priv *priv = netdev_priv(dev);
+
+ netif_stop_queue(dev);
+
+ mutex_lock(&tile_net_devs_for_channel_mutex);
+ tile_net_devs_for_channel[priv->channel] = NULL;
+ (void)tile_net_update(dev);
+ if (priv->loopify_channel >= 0) {
+ if (gxio_mpipe_link_close(&priv->loopify_link) != 0)
+ netdev_warn(dev, "Failed to close loopify link!\n");
+ priv->loopify_channel = -1;
+ }
+ if (priv->channel >= 0) {
+ if (gxio_mpipe_link_close(&priv->link) != 0)
+ netdev_warn(dev, "Failed to close link!\n");
+ priv->channel = -1;
+ }
+ priv->echannel = -1;
+ mutex_unlock(&tile_net_devs_for_channel_mutex);
+
+ return 0;
+}
+
+/* Determine the VA for a fragment. */
+static inline void *tile_net_frag_buf(skb_frag_t *f)
+{
+ unsigned long pfn = page_to_pfn(skb_frag_page(f));
+ return pfn_to_kaddr(pfn) + f->page_offset;
+}
+
+/* Acquire a completion entry and an egress slot, or if we can't,
+ * stop the queue and schedule the tx_wake timer.
+ */
+static s64 tile_net_equeue_try_reserve(struct net_device *dev,
+ struct tile_net_comps *comps,
+ gxio_mpipe_equeue_t *equeue,
+ int num_edescs)
+{
+ /* Try to acquire a completion entry. */
+ if (comps->comp_next - comps->comp_last < TILE_NET_MAX_COMPS - 1 ||
+ tile_net_free_comps(equeue, comps, 32, false) != 0) {
+
+ /* Try to acquire an egress slot. */
+ s64 slot = gxio_mpipe_equeue_try_reserve(equeue, num_edescs);
+ if (slot >= 0)
+ return slot;
+
+ /* Freeing some completions gives the equeue time to drain. */
+ tile_net_free_comps(equeue, comps, TILE_NET_MAX_COMPS, false);
+
+ slot = gxio_mpipe_equeue_try_reserve(equeue, num_edescs);
+ if (slot >= 0)
+ return slot;
+ }
+
+ /* Still nothing; give up and stop the queue for a short while. */
+ netif_stop_queue(dev);
+ tile_net_schedule_tx_wake_timer(dev);
+ return -1;
+}
+
+/* Determine how many edesc's are needed for TSO.
+ *
+ * Sometimes, if "sendfile()" requires copying, we will be called with
+ * "data" containing the header and payload, with "frags" being empty.
+ * Sometimes, for example when using NFS over TCP, a single segment can
+ * span 3 fragments. This requires special care.
+ */
+static int tso_count_edescs(struct sk_buff *skb)
+{
+ struct skb_shared_info *sh = skb_shinfo(skb);
+ unsigned int data_len = skb->data_len;
+ unsigned int p_len = sh->gso_size;
+ long f_id = -1; /* id of the current fragment */
+ long f_size = -1; /* size of the current fragment */
+ long f_used = -1; /* bytes used from the current fragment */
+ long n; /* size of the current piece of payload */
+ int num_edescs = 0;
+ int segment;
+
+ for (segment = 0; segment < sh->gso_segs; segment++) {
+
+ unsigned int p_used = 0;
+
+ /* One edesc for header and for each piece of the payload. */
+ for (num_edescs++; p_used < p_len; num_edescs++) {
+
+ /* Advance as needed. */
+ while (f_used >= f_size) {
+ f_id++;
+ f_size = sh->frags[f_id].size;
+ f_used = 0;
+ }
+
+ /* Use bytes from the current fragment. */
+ n = p_len - p_used;
+ if (n > f_size - f_used)
+ n = f_size - f_used;
+ f_used += n;
+ p_used += n;
+ }
+
+ /* The last segment may be less than gso_size. */
+ data_len -= p_len;
+ if (data_len < p_len)
+ p_len = data_len;
+ }
+
+ return num_edescs;
+}
+
+/* Prepare modified copies of the skbuff headers.
+ * FIXME: add support for IPv6.
+ */
+static void tso_headers_prepare(struct sk_buff *skb, unsigned char *headers,
+ s64 slot)
+{
+ struct skb_shared_info *sh = skb_shinfo(skb);
+ struct iphdr *ih;
+ struct tcphdr *th;
+ unsigned int data_len = skb->data_len;
+ unsigned char *data = skb->data;
+ unsigned int ih_off, th_off, sh_len, p_len;
+ unsigned int isum_seed, tsum_seed, id, seq;
+ long f_id = -1; /* id of the current fragment */
+ long f_size = -1; /* size of the current fragment */
+ long f_used = -1; /* bytes used from the current fragment */
+ long n; /* size of the current piece of payload */
+ int segment;
+
+ /* Locate original headers and compute various lengths. */
+ ih = ip_hdr(skb);
+ th = tcp_hdr(skb);
+ ih_off = skb_network_offset(skb);
+ th_off = skb_transport_offset(skb);
+ sh_len = th_off + tcp_hdrlen(skb);
+ p_len = sh->gso_size;
+
+ /* Set up seed values for IP and TCP csum and initialize id and seq. */
+ isum_seed = ((0xFFFF - ih->check) +
+ (0xFFFF - ih->tot_len) +
+ (0xFFFF - ih->id));
+ tsum_seed = th->check + (0xFFFF ^ htons(skb->len));
+ id = ntohs(ih->id);
+ seq = ntohl(th->seq);
+
+ /* Prepare all the headers. */
+ for (segment = 0; segment < sh->gso_segs; segment++) {
+ unsigned char *buf;
+ unsigned int p_used = 0;
+
+ /* Copy to the header memory for this segment. */
+ buf = headers + (slot % EQUEUE_ENTRIES) * HEADER_BYTES +
+ NET_IP_ALIGN;
+ memcpy(buf, data, sh_len);
+
+ /* Update copied ip header. */
+ ih = (struct iphdr *)(buf + ih_off);
+ ih->tot_len = htons(sh_len + p_len - ih_off);
+ ih->id = htons(id);
+ ih->check = csum_long(isum_seed + ih->tot_len +
+ ih->id) ^ 0xffff;
+
+ /* Update copied tcp header. */
+ th = (struct tcphdr *)(buf + th_off);
+ th->seq = htonl(seq);
+ th->check = csum_long(tsum_seed + htons(sh_len + p_len));
+ if (segment != sh->gso_segs - 1) {
+ th->fin = 0;
+ th->psh = 0;
+ }
+
+ /* Skip past the header. */
+ slot++;
+
+ /* Skip past the payload. */
+ while (p_used < p_len) {
+
+ /* Advance as needed. */
+ while (f_used >= f_size) {
+ f_id++;
+ f_size = sh->frags[f_id].size;
+ f_used = 0;
+ }
+
+ /* Use bytes from the current fragment. */
+ n = p_len - p_used;
+ if (n > f_size - f_used)
+ n = f_size - f_used;
+ f_used += n;
+ p_used += n;
+
+ slot++;
+ }
+
+ id++;
+ seq += p_len;
+
+ /* The last segment may be less than gso_size. */
+ data_len -= p_len;
+ if (data_len < p_len)
+ p_len = data_len;
+ }
+
+ /* Flush the headers so they are ready for hardware DMA. */
+ wmb();
+}
+
+/* Pass all the data to mpipe for egress. */
+static void tso_egress(struct net_device *dev, gxio_mpipe_equeue_t *equeue,
+ struct sk_buff *skb, unsigned char *headers, s64 slot)
+{
+ struct tile_net_priv *priv = netdev_priv(dev);
+ struct skb_shared_info *sh = skb_shinfo(skb);
+ unsigned int data_len = skb->data_len;
+ unsigned int p_len = sh->gso_size;
+ gxio_mpipe_edesc_t edesc_head = { { 0 } };
+ gxio_mpipe_edesc_t edesc_body = { { 0 } };
+ long f_id = -1; /* id of the current fragment */
+ long f_size = -1; /* size of the current fragment */
+ long f_used = -1; /* bytes used from the current fragment */
+ long n; /* size of the current piece of payload */
+ unsigned long tx_packets = 0, tx_bytes = 0;
+ unsigned int csum_start, sh_len;
+ int segment;
+
+ /* Prepare to egress the headers: set up header edesc. */
+ csum_start = skb_checksum_start_offset(skb);
+ sh_len = skb_transport_offset(skb) + tcp_hdrlen(skb);
+ edesc_head.csum = 1;
+ edesc_head.csum_start = csum_start;
+ edesc_head.csum_dest = csum_start + skb->csum_offset;
+ edesc_head.xfer_size = sh_len;
+
+ /* This is only used to specify the TLB. */
+ edesc_head.stack_idx = large_buffer_stack;
+ edesc_body.stack_idx = large_buffer_stack;
+
+ /* Egress all the edescs. */
+ for (segment = 0; segment < sh->gso_segs; segment++) {
+ void *va;
+ unsigned char *buf;
+ unsigned int p_used = 0;
+
+ /* Egress the header. */
+ buf = headers + (slot % EQUEUE_ENTRIES) * HEADER_BYTES +
+ NET_IP_ALIGN;
+ edesc_head.va = va_to_tile_io_addr(buf);
+ gxio_mpipe_equeue_put_at(equeue, edesc_head, slot);
+ slot++;
+
+ /* Egress the payload. */
+ while (p_used < p_len) {
+
+ /* Advance as needed. */
+ while (f_used >= f_size) {
+ f_id++;
+ f_size = sh->frags[f_id].size;
+ f_used = 0;
+ }
+
+ va = tile_net_frag_buf(&sh->frags[f_id]) + f_used;
+
+ /* Use bytes from the current fragment. */
+ n = p_len - p_used;
+ if (n > f_size - f_used)
+ n = f_size - f_used;
+ f_used += n;
+ p_used += n;
+
+ /* Egress a piece of the payload. */
+ edesc_body.va = va_to_tile_io_addr(va);
+ edesc_body.xfer_size = n;
+ edesc_body.bound = !(p_used < p_len);
+ gxio_mpipe_equeue_put_at(equeue, edesc_body, slot);
+ slot++;
+ }
+
+ tx_packets++;
+ tx_bytes += sh_len + p_len;
+
+ /* The last segment may be less than gso_size. */
+ data_len -= p_len;
+ if (data_len < p_len)
+ p_len = data_len;
+ }
+
+ /* Update stats. */
+ tile_net_stats_add(tx_packets, &priv->stats.tx_packets);
+ tile_net_stats_add(tx_bytes, &priv->stats.tx_bytes);
+}
+
+/* Do "TSO" handling for egress.
+ *
+ * Normally drivers set NETIF_F_TSO only to support hardware TSO;
+ * otherwise the stack uses scatter-gather to implement GSO in software.
+ * On our testing, enabling GSO support (via NETIF_F_SG) drops network
+ * performance down to around 7.5 Gbps on the 10G interfaces, although
+ * also dropping cpu utilization way down, to under 8%. But
+ * implementing "TSO" in the driver brings performance back up to line
+ * rate, while dropping cpu usage even further, to less than 4%. In
+ * practice, profiling of GSO shows that skb_segment() is what causes
+ * the performance overheads; we benefit in the driver from using
+ * preallocated memory to duplicate the TCP/IP headers.
+ */
+static int tile_net_tx_tso(struct sk_buff *skb, struct net_device *dev)
+{
+ struct tile_net_priv *priv = netdev_priv(dev);
+ struct tile_net_info *info = &__get_cpu_var(per_cpu_info);
+ int channel = priv->echannel;
+ struct tile_net_egress *egress = &egress_for_echannel[channel];
+ struct tile_net_comps *comps = info->comps_for_echannel[channel];
+ gxio_mpipe_equeue_t *equeue = egress->equeue;
+ unsigned long irqflags;
+ int num_edescs;
+ s64 slot;
+
+ /* Determine how many mpipe edesc's are needed. */
+ num_edescs = tso_count_edescs(skb);
+
+ local_irq_save(irqflags);
+
+ /* Set first reserved egress slot. */
+ slot = tile_net_equeue_try_reserve(dev, comps, equeue, num_edescs);
+ if (slot < 0) {
+ local_irq_restore(irqflags);
+ /* We set the tx_queue_len as 0, so there's no tx packet
+ * enqueuing. We simply drop the packet when the tx queue
+ * is full.
+ */
+ tile_net_stats_add(1, &priv->stats.tx_dropped);
+ return NETDEV_TX_OK;
+ }
+
+ /* Set up copies of header data properly. */
+ tso_headers_prepare(skb, egress->headers, slot);
+
+ /* Actually pass the data to the network hardware. */
+ tso_egress(dev, equeue, skb, egress->headers, slot);
+
+ /* Add a completion record. */
+ add_comp(equeue, comps, slot + num_edescs - 1, skb);
+
+ local_irq_restore(irqflags);
+
+ /* Make sure the egress timer is scheduled. */
+ tile_net_schedule_egress_timer(info);
+
+ return NETDEV_TX_OK;
+}
+
+/* Analyze the body and frags for a transmit request. */
+static unsigned int tile_net_tx_frags(struct frag *frags,
+ struct sk_buff *skb,
+ void *b_data, unsigned int b_len)
+{
+ unsigned int i, n = 0;
+
+ struct skb_shared_info *sh = skb_shinfo(skb);
+
+ if (b_len != 0) {
+ frags[n].buf = b_data;
+ frags[n++].length = b_len;
+ }
+
+ for (i = 0; i < sh->nr_frags; i++) {
+ skb_frag_t *f = &sh->frags[i];
+ frags[n].buf = tile_net_frag_buf(f);
+ frags[n++].length = skb_frag_size(f);
+ }
+
+ return n;
+}
+
+/* Help the kernel transmit a packet. */
+static int tile_net_tx(struct sk_buff *skb, struct net_device *dev)
+{
+ struct tile_net_priv *priv = netdev_priv(dev);
+ struct tile_net_info *info = &__get_cpu_var(per_cpu_info);
+ struct tile_net_egress *egress = &egress_for_echannel[priv->echannel];
+ gxio_mpipe_equeue_t *equeue = egress->equeue;
+ struct tile_net_comps *comps =
+ info->comps_for_echannel[priv->echannel];
+ unsigned int len = skb->len;
+ unsigned char *data = skb->data;
+ unsigned int num_edescs;
+ struct frag frags[MAX_FRAGS];
+ gxio_mpipe_edesc_t edescs[MAX_FRAGS];
+ unsigned long irqflags;
+ gxio_mpipe_edesc_t edesc = { { 0 } };
+ unsigned int i;
+ s64 slot;
+
+ /* Save the timestamp. */
+ dev->trans_start = jiffies;
+
+ if (skb_is_gso(skb))
+ return tile_net_tx_tso(skb, dev);
+
+ num_edescs = tile_net_tx_frags(frags, skb, data, skb_headlen(skb));
+
+ /* This is only used to specify the TLB. */
+ edesc.stack_idx = large_buffer_stack;
+
+ /* Prepare the edescs. */
+ for (i = 0; i < num_edescs; i++) {
+ edesc.xfer_size = frags[i].length;
+ edesc.va = va_to_tile_io_addr(frags[i].buf);
+ edescs[i] = edesc;
+ }
+
+ /* Mark the final edesc. */
+ edescs[num_edescs - 1].bound = 1;
+
+ /* Add checksum info to the initial edesc, if needed. */
+ if (skb->ip_summed == CHECKSUM_PARTIAL) {
+ unsigned int csum_start = skb_checksum_start_offset(skb);
+ edescs[0].csum = 1;
+ edescs[0].csum_start = csum_start;
+ edescs[0].csum_dest = csum_start + skb->csum_offset;
+ }
+
+ local_irq_save(irqflags);
+
+ /* Set first reserved egress slot. */
+ slot = tile_net_equeue_try_reserve(dev, comps, equeue, num_edescs);
+ if (slot < 0) {
+ local_irq_restore(irqflags);
+ /* We set the tx_queue_len as 0, so there's no tx packet
+ * enqueuing. We simply drop the packet when the tx queue
+ * is full.
+ */
+ tile_net_stats_add(1, &priv->stats.tx_dropped);
+ return NETDEV_TX_OK;
+ }
+
+ for (i = 0; i < num_edescs; i++)
+ gxio_mpipe_equeue_put_at(equeue, edescs[i], slot++);
+
+ /* Add a completion record. */
+ add_comp(equeue, comps, slot - 1, skb);
+
+ /* NOTE: Use ETH_ZLEN for short packets (e.g. 42 < 60). */
+ tile_net_stats_add(1, &priv->stats.tx_packets);
+ tile_net_stats_add(max_t(unsigned int, len, ETH_ZLEN),
+ &priv->stats.tx_bytes);
+
+ local_irq_restore(irqflags);
+
+ /* Make sure the egress timer is scheduled. */
+ tile_net_schedule_egress_timer(info);
+
+ return NETDEV_TX_OK;
+}
+
+/* Deal with a transmit timeout. */
+static void tile_net_tx_timeout(struct net_device *dev)
+{
+ netif_wake_queue(dev);
+}
+
+/* Ioctl commands. */
+static int tile_net_ioctl(struct net_device *dev, struct ifreq *rq, int cmd)
+{
+ return -EOPNOTSUPP;
+}
+
+/* Get system network statistics for device. */
+static struct net_device_stats *tile_net_get_stats(struct net_device *dev)
+{
+ struct tile_net_priv *priv = netdev_priv(dev);
+ return &priv->stats;
+}
+
+/* Change the MTU. */
+static int tile_net_change_mtu(struct net_device *dev, int new_mtu)
+{
+ if ((new_mtu < 68) || (new_mtu > 1500))
+ return -EINVAL;
+ dev->mtu = new_mtu;
+ return 0;
+}
+
+/* Change the Ethernet address of the NIC.
+ *
+ * The hypervisor driver does not support changing MAC address. However,
+ * the hardware does not do anything with the MAC address, so the address
+ * which gets used on outgoing packets, and which is accepted on incoming
+ * packets, is completely up to us.
+ *
+ * Returns 0 on success, negative on failure.
+ */
+static int tile_net_set_mac_address(struct net_device *dev, void *p)
+{
+ struct sockaddr *addr = p;
+
+ if (!is_valid_ether_addr(addr->sa_data))
+ return -EINVAL;
+ memcpy(dev->dev_addr, addr->sa_data, dev->addr_len);
+ return 0;
+}
+
+#ifdef CONFIG_NET_POLL_CONTROLLER
+/* Polling 'interrupt' - used by things like netconsole to send skbs
+ * without having to re-enable interrupts. It's not called while
+ * the interrupt routine is executing.
+ */
+static void tile_net_netpoll(struct net_device *dev)
+{
+ disable_percpu_irq(ingress_irq);
+ tile_net_handle_ingress_irq(ingress_irq, NULL);
+ enable_percpu_irq(ingress_irq, 0);
+}
+#endif
+
+static const struct net_device_ops tile_net_ops = {
+ .ndo_open = tile_net_open,
+ .ndo_stop = tile_net_stop,
+ .ndo_start_xmit = tile_net_tx,
+ .ndo_do_ioctl = tile_net_ioctl,
+ .ndo_get_stats = tile_net_get_stats,
+ .ndo_change_mtu = tile_net_change_mtu,
+ .ndo_tx_timeout = tile_net_tx_timeout,
+ .ndo_set_mac_address = tile_net_set_mac_address,
+#ifdef CONFIG_NET_POLL_CONTROLLER
+ .ndo_poll_controller = tile_net_netpoll,
+#endif
+};
+
+/* The setup function.
+ *
+ * This uses ether_setup() to assign various fields in dev, including
+ * setting IFF_BROADCAST and IFF_MULTICAST, then sets some extra fields.
+ */
+static void tile_net_setup(struct net_device *dev)
+{
+ ether_setup(dev);
+ dev->netdev_ops = &tile_net_ops;
+ dev->watchdog_timeo = TILE_NET_TIMEOUT;
+ dev->features |= NETIF_F_LLTX;
+ dev->features |= NETIF_F_HW_CSUM;
+ dev->features |= NETIF_F_SG;
+ dev->features |= NETIF_F_TSO;
+ dev->tx_queue_len = 0;
+ dev->mtu = 1500;
+}
+
+/* Allocate the device structure, register the device, and obtain the
+ * MAC address from the hypervisor.
+ */
+static void tile_net_dev_init(const char *name, const uint8_t *mac)
+{
+ int ret;
+ int i;
+ int nz_addr = 0;
+ struct net_device *dev;
+ struct tile_net_priv *priv;
+
+ /* HACK: Ignore "loop" links. */
+ if (strncmp(name, "loop", 4) == 0)
+ return;
+
+ /* Allocate the device structure. Normally, "name" is a
+ * template, instantiated by register_netdev(), but not for us.
+ */
+ dev = alloc_netdev(sizeof(*priv), name, tile_net_setup);
+ if (!dev) {
+ pr_err("alloc_netdev(%s) failed\n", name);
+ return;
+ }
+
+ /* Initialize "priv". */
+ priv = netdev_priv(dev);
+ memset(priv, 0, sizeof(*priv));
+ priv->dev = dev;
+ priv->channel = -1;
+ priv->loopify_channel = -1;
+ priv->echannel = -1;
+
+ /* Get the MAC address and set it in the device struct; this must
+ * be done before the device is opened. If the MAC is all zeroes,
+ * we use a random address, since we're probably on the simulator.
+ */
+ for (i = 0; i < 6; i++)
+ nz_addr |= mac[i];
+
+ if (nz_addr) {
+ memcpy(dev->dev_addr, mac, 6);
+ dev->addr_len = 6;
+ } else {
+ random_ether_addr(dev->dev_addr);
+ }
+
+ /* Initialize the transmit wake timer. */
+ hrtimer_init(&priv->tx_wake_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
+ priv->tx_wake_timer.function = tile_net_handle_tx_wake_timer;
+
+ /* Register the network device. */
+ ret = register_netdev(dev);
+ if (ret) {
+ netdev_err(dev, "register_netdev failed %d\n", ret);
+ free_netdev(dev);
+ return;
+ }
+}
+
+/* Per-cpu module initialization. */
+static void tile_net_init_module_percpu(void *unused)
+{
+ struct tile_net_info *info = &__get_cpu_var(per_cpu_info);
+ int my_cpu = smp_processor_id();
+
+ info->has_iqueue = false;
+
+ info->my_cpu = my_cpu;
+
+ /* Initialize the egress timer. */
+ hrtimer_init(&info->egress_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
+ info->egress_timer.function = tile_net_handle_egress_timer;
+}
+
+/* Module initialization. */
+static int __init tile_net_init_module(void)
+{
+ int i;
+ char name[GXIO_MPIPE_LINK_NAME_LEN];
+ uint8_t mac[6];
+
+ pr_info("Tilera Network Driver\n");
+
+ mutex_init(&tile_net_devs_for_channel_mutex);
+
+ /* Initialize each CPU. */
+ on_each_cpu(tile_net_init_module_percpu, NULL, 1);
+
+ /* Find out what devices we have, and initialize them. */
+ for (i = 0; gxio_mpipe_link_enumerate_mac(i, name, mac) >= 0; i++)
+ tile_net_dev_init(name, mac);
+
+ if (!network_cpus_init())
+ network_cpus_map = *cpu_online_mask;
+
+ return 0;
+}
+
+module_init(tile_net_init_module);
--
1.6.5.2
^ permalink raw reply related
* Re: tcp wifi upload performance and lots of ACKs
From: Eric Dumazet @ 2012-06-04 20:18 UTC (permalink / raw)
To: Ben Greear; +Cc: netdev
In-Reply-To: <4FCD16A4.9070705@candelatech.com>
On Mon, 2012-06-04 at 13:12 -0700, Ben Greear wrote:
> That sounds like a horrible hack :)
>
Yep, but could be usefull on a gateway/router, if you cant change the
TCP stack of the clients.
^ permalink raw reply
* Re: tcp wifi upload performance and lots of ACKs
From: Daniel Baluta @ 2012-06-04 20:15 UTC (permalink / raw)
To: Ben Greear; +Cc: netdev
In-Reply-To: <4FCD15E7.4080700@candelatech.com>
On Mon, Jun 4, 2012 at 11:09 PM, Ben Greear <greearb@candelatech.com> wrote:
> On 06/04/2012 12:22 PM, Daniel Baluta wrote:
>>
>> On Mon, Jun 4, 2012 at 9:29 PM, Ben Greear<greearb@candelatech.com>
>> wrote:
>>>
>>> I'm going some TCP performance testing on wifi -> LAN interface
>>> connections.
>>> With
>>> UDP, we can get around 250Mbps of payload throughput. With TCP, max is
>>> about 80Mbps.
>>>
>>> I think the problem is that there are way too many ACK packets, and
>>> bi-directional
>>> traffic on wifi interfaces really slows things down. (About 7000 pkts
>>> per
>>> second in
>>> upload direction, 2000 pps download. And the vast majority of the
>>> download
>>> pkts
>>> are 66 byte ACK pkts from what I can tell.)
>>>
>>> Kernel is 3.3.7+
>>>
>>> Anyone know of any tuning parameters that would let the receiving socket
>>> wait a
>>> bit longer and send more ACK data in fewer packets?
>>
>>
>> An ACK is generated after every second full sized segment or a timeout
>> expires.
>>
>> Currently, there is no way to tune these parameters. Here is an
>> experimental
>> patch [1]. If anyone, thinks that this patch has a chance to get accepted
>> I will be happily try to further improve it.
>
>
> It looks like it could be useful for my case, but I would also want
> per-socket options to set the min/max ack delay so that the settings
> are not just system-wide.
>
> I can at least test this, and perhaps even hack on the code if
> you are not interested in the per-socket settings...
Yes, indeed this should be a per socket option. I will be
back with a patch in the next days.
Meanwhile, it would be great if you could test my previous patch.
thanks,
Daniel.
^ permalink raw reply
* Re: tcp wifi upload performance and lots of ACKs
From: Ben Greear @ 2012-06-04 20:12 UTC (permalink / raw)
To: Eric Dumazet; +Cc: netdev
In-Reply-To: <1338838352.2760.1906.camel@edumazet-glaptop>
On 06/04/2012 12:32 PM, Eric Dumazet wrote:
> On Mon, 2012-06-04 at 11:29 -0700, Ben Greear wrote:
>> I'm going some TCP performance testing on wifi -> LAN interface connections. With
>> UDP, we can get around 250Mbps of payload throughput. With TCP, max is about 80Mbps.
>>
>> I think the problem is that there are way too many ACK packets, and bi-directional
>> traffic on wifi interfaces really slows things down. (About 7000 pkts per second in
>> upload direction, 2000 pps download. And the vast majority of the download pkts
>> are 66 byte ACK pkts from what I can tell.)
>>
>> Kernel is 3.3.7+
>>
>> Anyone know of any tuning parameters that would let the receiving socket wait a
>> bit longer and send more ACK data in fewer packets?
>
> Well, thats half duplex days...
WiFi is still half-duplex, and isn't changing any time soon I think.
> There is the ACK every 2 packets rule of thumb, so that tcp sender can
> increase its cwnd.
>
> Then, some folks tried submitting patches to make '2' more like 10 or
> 15, but this went nowhere.
>
> Other idea is to arm a timer and defer ACK sending, in the hope we
> receive another packet very soon.
From a quick read of Daniel's patch..it seems there is already a
timer that could be used for this?
> That could be done with a special qdisc, sort of netem...
That sounds like a horrible hack :)
Ben
--
Ben Greear <greearb@candelatech.com>
Candela Technologies Inc http://www.candelatech.com
^ permalink raw reply
* Re: tcp wifi upload performance and lots of ACKs
From: Ben Greear @ 2012-06-04 20:09 UTC (permalink / raw)
To: Daniel Baluta; +Cc: netdev
In-Reply-To: <CAEnQRZCNUYmP88Ocm_nG7gpA1Qcwy1tOc6kgCgZ7RqXcxQsHhg@mail.gmail.com>
On 06/04/2012 12:22 PM, Daniel Baluta wrote:
> On Mon, Jun 4, 2012 at 9:29 PM, Ben Greear<greearb@candelatech.com> wrote:
>> I'm going some TCP performance testing on wifi -> LAN interface connections.
>> With
>> UDP, we can get around 250Mbps of payload throughput. With TCP, max is
>> about 80Mbps.
>>
>> I think the problem is that there are way too many ACK packets, and
>> bi-directional
>> traffic on wifi interfaces really slows things down. (About 7000 pkts per
>> second in
>> upload direction, 2000 pps download. And the vast majority of the download
>> pkts
>> are 66 byte ACK pkts from what I can tell.)
>>
>> Kernel is 3.3.7+
>>
>> Anyone know of any tuning parameters that would let the receiving socket
>> wait a
>> bit longer and send more ACK data in fewer packets?
>
> An ACK is generated after every second full sized segment or a timeout
> expires.
>
> Currently, there is no way to tune these parameters. Here is an experimental
> patch [1]. If anyone, thinks that this patch has a chance to get accepted
> I will be happily try to further improve it.
It looks like it could be useful for my case, but I would also want
per-socket options to set the min/max ack delay so that the settings
are not just system-wide.
I can at least test this, and perhaps even hack on the code if
you are not interested in the per-socket settings...
Thanks,
Ben
--
Ben Greear <greearb@candelatech.com>
Candela Technologies Inc http://www.candelatech.com
^ permalink raw reply
* Re: [PATCH net-next] net: netdev_alloc_skb() use build_skb()
From: Eric Dumazet @ 2012-06-04 20:05 UTC (permalink / raw)
To: Michael S. Tsirkin; +Cc: Willy Tarreau, David Miller, netdev
In-Reply-To: <20120604195642.GA2069@redhat.com>
On Mon, 2012-06-04 at 22:56 +0300, Michael S. Tsirkin wrote:
> And just to explain why I'm asking, if it's OK to
> declare 2K when you use 4K, we can do (effectively):
>
> + skb->truesize += PAGE_SIZE * nfrags;
> - skb->truesize += min(1500, skb->data_len);
>
> which means with 1500 byte packets we can use
> as much memory as we did before
> 4b727361f0bc7ee7378298941066d8aa15023ffb
>
How are you sure data_len is >= 1500 ?
If you know that you use a full page for a fragment, then PAGE_SIZE is
better than 1500
If you share a page with 2/4 frames (But not one hundred), you can
assume risk of underestimation is really low.
^ permalink raw reply
* Re: [PATCH net-next] net: netdev_alloc_skb() use build_skb()
From: Michael S. Tsirkin @ 2012-06-04 19:56 UTC (permalink / raw)
To: Eric Dumazet; +Cc: Willy Tarreau, David Miller, netdev
In-Reply-To: <20120604194330.GA1648@redhat.com>
On Mon, Jun 04, 2012 at 10:43:30PM +0300, Michael S. Tsirkin wrote:
> On Mon, Jun 04, 2012 at 09:29:45PM +0200, Eric Dumazet wrote:
> > On Mon, 2012-06-04 at 21:16 +0300, Michael S. Tsirkin wrote:
> >
> > > Yes but if a tcp socket then hangs on, on one of the fragments,
> > > while the other has been freed, the whole page is still
> > > never reused, right?
> > >
> > > Doesn't this mean truesize should be 4K?
> > >
> >
> > Yes, or more exactly PAGE_SIZE, but then performance would really go
> > down on machines with 64KB pages.
> > Maybe we should make the whole frag
> > head idea enabled only for PAGE_SIZE=4096.
> >
> > Not sure we want to track precise truesize, as the minimum truesize is
> > SKB_DATA_ALIGN(length + NET_SKB_PAD) + SKB_DATA_ALIGN(sizeof(struct
> > skb_shared_info)) (64 + 64 + 320) = 448
> >
> > Its not like buggy drivers that used truesize = length
> >
> >
>
> Interesting. But where's the threshold?
And just to explain why I'm asking, if it's OK to
declare 2K when you use 4K, we can do (effectively):
+ skb->truesize += PAGE_SIZE * nfrags;
- skb->truesize += min(1500, skb->data_len);
which means with 1500 byte packets we can use
as much memory as we did before
4b727361f0bc7ee7378298941066d8aa15023ffb
> --
> MST
^ permalink raw reply
* Re: [PATCH net-next] net: netdev_alloc_skb() use build_skb()
From: Eric Dumazet @ 2012-06-04 19:56 UTC (permalink / raw)
To: Michael S. Tsirkin; +Cc: Willy Tarreau, David Miller, netdev
In-Reply-To: <20120604194806.GB1648@redhat.com>
On Mon, 2012-06-04 at 22:48 +0300, Michael S. Tsirkin wrote:
> If I do this what will truesize be? 128, no?
My example was not correct, since you must have enough room for the
SKB_DATA_ALIGN(sizeof(struct skb_shared_info)) ( 320 bytes )
So it would be 128 + 320 = 448
^ permalink raw reply
* Re: [PATCH net-next] net: netdev_alloc_skb() use build_skb()
From: Eric Dumazet @ 2012-06-04 19:52 UTC (permalink / raw)
To: Michael S. Tsirkin; +Cc: Willy Tarreau, David Miller, netdev
In-Reply-To: <20120604194330.GA1648@redhat.com>
On Mon, 2012-06-04 at 22:43 +0300, Michael S. Tsirkin wrote:
> On Mon, Jun 04, 2012 at 09:29:45PM +0200, Eric Dumazet wrote:
> > On Mon, 2012-06-04 at 21:16 +0300, Michael S. Tsirkin wrote:
> >
> > > Yes but if a tcp socket then hangs on, on one of the fragments,
> > > while the other has been freed, the whole page is still
> > > never reused, right?
> > >
> > > Doesn't this mean truesize should be 4K?
> > >
> >
> > Yes, or more exactly PAGE_SIZE, but then performance would really go
> > down on machines with 64KB pages.
> > Maybe we should make the whole frag
> > head idea enabled only for PAGE_SIZE=4096.
> >
> > Not sure we want to track precise truesize, as the minimum truesize is
> > SKB_DATA_ALIGN(length + NET_SKB_PAD) + SKB_DATA_ALIGN(sizeof(struct
> > skb_shared_info)) (64 + 64 + 320) = 448
> >
> > Its not like buggy drivers that used truesize = length
> >
> >
>
> Interesting. But where's the threshold?
>
It all depends on the global limit you have on your machine.
If you allow tcp memory to use 10% of ram, then a systematic x4 error
would allow it to use 40% of ram. Mabe not enough to crash.
Now you have to find a real workload able to hit this limit for real...
But, if you "allow" a driver to claim a truesize of 1 (instead of 4096),
you can reach the limit and OOM faster
You know, even the current page stored for each socket (sk_sndmsg_page)
can be a problem if you setup 1.000.000 tcp sockets. That can consume
4GB of ram (added to inode/sockets themselves)
This is not really taken into account right now...
^ permalink raw reply
* Re: [PATCH net-next 5/5] gianfar_ethtool: coding style and whitespace cleanups
From: David Miller @ 2012-06-04 19:52 UTC (permalink / raw)
To: jan.ceuleers; +Cc: b06378, joe, netdev
In-Reply-To: <4FCD084D.6020408@computer.org>
From: Jan Ceuleers <jan.ceuleers@computer.org>
Date: Mon, 04 Jun 2012 21:11:09 +0200
> Well then I'm sorry but I won't be resubmitting
Because you can't test the build?
You absolutely can, on any architecture, that's how I found your typo.
Force the build with "make path/to/driver/foo.o" and scan through the
non-architecture-specific warnings and errors.
^ permalink raw reply
* Re: [PATCH net-next] net: netdev_alloc_skb() use build_skb()
From: Michael S. Tsirkin @ 2012-06-04 19:48 UTC (permalink / raw)
To: Eric Dumazet; +Cc: Willy Tarreau, David Miller, netdev
In-Reply-To: <1338837842.2760.1883.camel@edumazet-glaptop>
On Mon, Jun 04, 2012 at 09:24:02PM +0200, Eric Dumazet wrote:
> On Mon, 2012-06-04 at 21:16 +0300, Michael S. Tsirkin wrote:
>
> > Will take a look, thanks.
> > By the way, this comment at build_skb:
> > * @frag_size: size of fragment, or 0 if head was kmalloced
> >
> > is not very clear to me. Could you clarify what exactly size
> > of fragment means in this context?
> >
>
>
> If your driver did :
>
> data = kmalloc(100) then you use @frag_size=0, so that build_skb() does
> the ksize(data) to fetch real size (It can depend on slab/slub/sob
> allocator)
>
>
> If you used netdev_alloc_frag(128), then you use 128 because there is no
> way build_skb() can guess the size of the fragment. Its also how we
> signal to build_skb() that skb->head_frag is set to 1.
>
> __netdev_alloc_skb() for example does :
>
> void *data = netdev_alloc_frag(fragsz);
> skb = build_skb(data, fragsz);
>
If I do this what will truesize be? 128, no?
^ permalink raw reply
* Re: [PATCH net-next] net: netdev_alloc_skb() use build_skb()
From: Michael S. Tsirkin @ 2012-06-04 19:43 UTC (permalink / raw)
To: Eric Dumazet; +Cc: Willy Tarreau, David Miller, netdev
In-Reply-To: <1338838185.2760.1899.camel@edumazet-glaptop>
On Mon, Jun 04, 2012 at 09:29:45PM +0200, Eric Dumazet wrote:
> On Mon, 2012-06-04 at 21:16 +0300, Michael S. Tsirkin wrote:
>
> > Yes but if a tcp socket then hangs on, on one of the fragments,
> > while the other has been freed, the whole page is still
> > never reused, right?
> >
> > Doesn't this mean truesize should be 4K?
> >
>
> Yes, or more exactly PAGE_SIZE, but then performance would really go
> down on machines with 64KB pages.
> Maybe we should make the whole frag
> head idea enabled only for PAGE_SIZE=4096.
>
> Not sure we want to track precise truesize, as the minimum truesize is
> SKB_DATA_ALIGN(length + NET_SKB_PAD) + SKB_DATA_ALIGN(sizeof(struct
> skb_shared_info)) (64 + 64 + 320) = 448
>
> Its not like buggy drivers that used truesize = length
>
>
Interesting. But where's the threshold?
--
MST
^ permalink raw reply
* Re: tcp wifi upload performance and lots of ACKs
From: Eric Dumazet @ 2012-06-04 19:32 UTC (permalink / raw)
To: Ben Greear; +Cc: netdev
In-Reply-To: <4FCCFE76.3060304@candelatech.com>
On Mon, 2012-06-04 at 11:29 -0700, Ben Greear wrote:
> I'm going some TCP performance testing on wifi -> LAN interface connections. With
> UDP, we can get around 250Mbps of payload throughput. With TCP, max is about 80Mbps.
>
> I think the problem is that there are way too many ACK packets, and bi-directional
> traffic on wifi interfaces really slows things down. (About 7000 pkts per second in
> upload direction, 2000 pps download. And the vast majority of the download pkts
> are 66 byte ACK pkts from what I can tell.)
>
> Kernel is 3.3.7+
>
> Anyone know of any tuning parameters that would let the receiving socket wait a
> bit longer and send more ACK data in fewer packets?
Well, thats half duplex days...
There is the ACK every 2 packets rule of thumb, so that tcp sender can
increase its cwnd.
Then, some folks tried submitting patches to make '2' more like 10 or
15, but this went nowhere.
Other idea is to arm a timer and defer ACK sending, in the hope we
receive another packet very soon.
That could be done with a special qdisc, sort of netem...
^ permalink raw reply
* Re: [PATCH net-next] net: netdev_alloc_skb() use build_skb()
From: Eric Dumazet @ 2012-06-04 19:29 UTC (permalink / raw)
To: Michael S. Tsirkin; +Cc: Willy Tarreau, David Miller, netdev
In-Reply-To: <20120604181623.GF32205@redhat.com>
On Mon, 2012-06-04 at 21:16 +0300, Michael S. Tsirkin wrote:
> Yes but if a tcp socket then hangs on, on one of the fragments,
> while the other has been freed, the whole page is still
> never reused, right?
>
> Doesn't this mean truesize should be 4K?
>
Yes, or more exactly PAGE_SIZE, but then performance would really go
down on machines with 64KB pages. Maybe we should make the whole frag
head idea enabled only for PAGE_SIZE=4096.
Not sure we want to track precise truesize, as the minimum truesize is
SKB_DATA_ALIGN(length + NET_SKB_PAD) + SKB_DATA_ALIGN(sizeof(struct
skb_shared_info)) (64 + 64 + 320) = 448
Its not like buggy drivers that used truesize = length
^ permalink raw reply
* Re: [PATCH 3/3] Revert Backoff [v3]: Calculate TCP's connection close threshold as a time value.
From: Ilpo Järvinen @ 2012-06-04 19:18 UTC (permalink / raw)
To: Damian Lukowski; +Cc: Jerry Chu, Netdev, David Miller
In-Reply-To: <1338832247.5299.4.camel@nexus>
On Mon, 4 Jun 2012, Damian Lukowski wrote:
> please verify, I understood you correctly.
>
> You have set TCP_RTO_MIN to a lower value, e.g. 0.002 seconds to improve
> your internal low-latency traffic. Because of the improvement, R1
> timeouts are triggered too fast for external high-RTT traffic. Is that
> correct?
> If so, may I suggest to set tcp_retries1 to a higher value? For
> TCP_RTO_MIN == 0.002 and tcp_retries1 == 10, R1 will be calculated to
> approximately 4 seconds.
>
> Is that ok?
I suppose what he meant is that you could have e.g., 60sec RTT and with
small enough retries the timeout calculation yields to some timeout
smaller than 60 secs, and therefore no retransmissions are made which is
certainly not a desirable property? ...This is valid issue even if no min
rto tweaking was done but can of course get much worse if min rto is
shorter.
I agree with his proposed solution:
> > I think retransmits_timed_out() should check against both time
> > duration and retrans count (icsk_retransmits).
...that is, use both pseudo timeout check of the current code and the
previously used icsk_retransmits compare at the same time.
--
i.
^ permalink raw reply
* Re: [PATCH net-next] net: netdev_alloc_skb() use build_skb()
From: Eric Dumazet @ 2012-06-04 19:24 UTC (permalink / raw)
To: Michael S. Tsirkin; +Cc: Willy Tarreau, David Miller, netdev
In-Reply-To: <20120604181636.GG32205@redhat.com>
On Mon, 2012-06-04 at 21:16 +0300, Michael S. Tsirkin wrote:
> Will take a look, thanks.
> By the way, this comment at build_skb:
> * @frag_size: size of fragment, or 0 if head was kmalloced
>
> is not very clear to me. Could you clarify what exactly size
> of fragment means in this context?
>
If your driver did :
data = kmalloc(100) then you use @frag_size=0, so that build_skb() does
the ksize(data) to fetch real size (It can depend on slab/slub/sob
allocator)
If you used netdev_alloc_frag(128), then you use 128 because there is no
way build_skb() can guess the size of the fragment. Its also how we
signal to build_skb() that skb->head_frag is set to 1.
__netdev_alloc_skb() for example does :
void *data = netdev_alloc_frag(fragsz);
skb = build_skb(data, fragsz);
^ permalink raw reply
* Re: tcp wifi upload performance and lots of ACKs
From: Daniel Baluta @ 2012-06-04 19:22 UTC (permalink / raw)
To: Ben Greear; +Cc: netdev
In-Reply-To: <4FCCFE76.3060304@candelatech.com>
On Mon, Jun 4, 2012 at 9:29 PM, Ben Greear <greearb@candelatech.com> wrote:
> I'm going some TCP performance testing on wifi -> LAN interface connections.
> With
> UDP, we can get around 250Mbps of payload throughput. With TCP, max is
> about 80Mbps.
>
> I think the problem is that there are way too many ACK packets, and
> bi-directional
> traffic on wifi interfaces really slows things down. (About 7000 pkts per
> second in
> upload direction, 2000 pps download. And the vast majority of the download
> pkts
> are 66 byte ACK pkts from what I can tell.)
>
> Kernel is 3.3.7+
>
> Anyone know of any tuning parameters that would let the receiving socket
> wait a
> bit longer and send more ACK data in fewer packets?
An ACK is generated after every second full sized segment or a timeout
expires.
Currently, there is no way to tune these parameters. Here is an experimental
patch [1]. If anyone, thinks that this patch has a chance to get accepted
I will be happily try to further improve it.
>
> Packet traces and other info available if anyone wants to take a look.
thanks,
Daniel.
[1] http://marc.info/?l=linux-netdev&m=131983649130350&w=2
^ permalink raw reply
* Re: [PATCH net-next 5/5] gianfar_ethtool: coding style and whitespace cleanups
From: Jan Ceuleers @ 2012-06-04 19:11 UTC (permalink / raw)
To: David Miller; +Cc: b06378, joe, netdev
In-Reply-To: <20120604.140850.1847853625568125563.davem@davemloft.net>
On 06/04/2012 08:08 PM, David Miller wrote:
> From: Jan Ceuleers <jan.ceuleers@computer.org>
> Date: Mon, 4 Jun 2012 18:31:56 +0200
>
>> - sizeof(struct gfar_mask_entry),
>> - gfar_comp, &gfar_swap);
>> + sizeof(struct gfar_mask_entry),
>> + far_comp, &gfar_swap);
>
> Don't send me crap you haven't even compile tested.
>
> I'm tossing this entire patch series out, don't resubmit until you've
> tested every single patch.
>
Well then I'm sorry but I won't be resubmitting
^ permalink raw reply
* Re: [PATCH iproute2 0/3] CAN Filter/Classifier
From: Stephen Hemminger @ 2012-06-04 19:13 UTC (permalink / raw)
To: Rostislav Lisovy; +Cc: netdev, linux-can, lartc, pisa, sojkam1
In-Reply-To: <1338826149-11604-1-git-send-email-lisovy@gmail.com>
On Mon, 4 Jun 2012 18:09:06 +0200
Rostislav Lisovy <lisovy@gmail.com> wrote:
> This classifier classifies CAN frames (AF_CAN) according to their
> identifiers. This functionality can not be easily achieved with
> existing classifiers, such as u32. This classifier can be used
> with any available qdisc and it is able to classify both SFF
> or EFF frames.
>
> The filtering rules for EFF frames are stored in an array, which
> is traversed during classification. A bitmap is used to store SFF
> rules -- one bit for each ID.
>
> More info about the project:
> http://rtime.felk.cvut.cz/can/socketcan-qdisc-final.pdf
>
>
> Rostislav Lisovy (3):
> Add missing can.h
> CAN Filter/Classifier -- Source code
> CAN Filter/Classifier -- Documentation
>
> include/linux/can.h | 112 ++++++++++++++++++++++
> include/linux/pkt_cls.h | 10 ++
> man/man8/tc-can.8 | 97 +++++++++++++++++++
> tc/Makefile | 1 +
> tc/f_can.c | 238 +++++++++++++++++++++++++++++++++++++++++++++++
> 5 files changed, 458 insertions(+)
> create mode 100644 include/linux/can.h
> create mode 100644 man/man8/tc-can.8
> create mode 100644 tc/f_can.c
Please resubmit these when the necessary upstream pieces are in Linus's tree.
That will be during the 3.6 merge window.
^ permalink raw reply
* Re: [PATCH iproute2 1/3] Add missing can.h
From: Stephen Hemminger @ 2012-06-04 19:10 UTC (permalink / raw)
To: Rostislav Lisovy; +Cc: netdev, linux-can, lartc, pisa, sojkam1
In-Reply-To: <1338826149-11604-2-git-send-email-lisovy@gmail.com>
On Mon, 4 Jun 2012 18:09:07 +0200
Rostislav Lisovy <lisovy@gmail.com> wrote:
> This header file is slightly modified version copied from
> Linux kernel v. 3.3. It contains defines necessary for working
> with AF_CAN packets.
>
> Signed-off-by: Rostislav Lisovy <lisovy@gmail.com>
Ok, but I will put in can.h but it will be done by copying the result
of the kernel 'make headers_install' which does the standard
removal of #ifdef kernel pieces. In iproute2, all kernel headers
used should come from this process.
^ permalink raw reply
* RE: [PATCH] net: compute a more reasonable default ip6_rt_max_size
From: Lubashev, Igor @ 2012-06-04 19:04 UTC (permalink / raw)
To: David Miller, eric.dumazet@gmail.com
Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Arun Sharma
In-Reply-To: <83CE6FF8F6C9B2468A618FC2C51267260F303CD88B@USMBX1.msg.corp.akamai.com>
David and Eric,
Any news about this? We definitely have many machines that are experiencing abnormal behavior under ipv6 load. The machines are healthier when the ipv6 route cache is increased to 64K, but I am afraid this is a band-aid that is hiding the actual problems.
So, could you address the concerns about the code in fib6_age? I can see three potential problems with it:
1. The meaning/use of NTF_ROUTER flag is inverted in 3.4
2. A potential NULL-pointer exception in pre-3.4 versions. In particular, "rt->rt6i_nexthop" (version 2.6.37) is checked for NULL in (almost?) all cases of referencing that field. I do not know for sure about "dst_get_neighbour_raw(&rt->dst)" in 3.0.32.
3. In all cases, an RTF_GATEWAY entry with __refcount > 0 may be garbage collected. That seems like a wrong thing to do. Is it?
Thank you!
- Igor
-----Original Message-----
From: Lubashev, Igor
Sent: Wednesday, May 30, 2012 7:50 PM
To: David Miller; Arun Sharma
Cc: eric.dumazet@gmail.com; netdev@vger.kernel.org; linux-kernel@vger.kernel.org
Subject: Re: [PATCH] net: compute a more reasonable default ip6_rt_max_size
>It's possible that there is a bug somewhere - we didn't get a chance to
>dig deeper. What we observed is that as we got close to the 4096 limit,
>some hosts were becoming unreachable. A modest increase in the routing
>table size made things better.
First of all, we have observed the same thing.
While I am not an expert in this area of the routing code, the function fib6_age in net/ipv6/ip6_fib.c puzzles me.
In kernel version 2.6.37, we have net/ipv6/ip6_fib.c:
static int fib6_age(struct rt6_info *rt, void *arg) {
unsigned long now = jiffies;
if (rt->rt6i_flags&RTF_EXPIRES && rt->rt6i_expires) {
if (time_after(now, rt->rt6i_expires)) {
RT6_TRACE("expiring %p\n", rt);
return -1;
}
gc_args.more++;
} else if (rt->rt6i_flags & RTF_CACHE) {
if (atomic_read(&rt->dst.__refcnt) == 0 &&
time_after_eq(now, rt->dst.lastuse + gc_args.timeout)) {
RT6_TRACE("aging clone %p\n", rt);
return -1;
} else if ((rt->rt6i_flags & RTF_GATEWAY) &&
(!(rt->rt6i_nexthop->flags & NTF_ROUTER))) {
RT6_TRACE("purging route %p via non-router but gateway\n",
rt);
return -1;
}
gc_args.more++;
}
return 0;
}
In kernel 3.0.32, we have net/ipv6/ip6_fib.c:
static int fib6_age(struct rt6_info *rt, void *arg) {
unsigned long now = jiffies;
if (rt->rt6i_flags&RTF_EXPIRES && rt->rt6i_expires) {
if (time_after(now, rt->rt6i_expires)) {
RT6_TRACE("expiring %p\n", rt);
return -1;
}
gc_args.more++;
} else if (rt->rt6i_flags & RTF_CACHE) {
if (atomic_read(&rt->dst.__refcnt) == 0 &&
time_after_eq(now, rt->dst.lastuse + gc_args.timeout)) {
RT6_TRACE("aging clone %p\n", rt);
return -1;
} else if ((rt->rt6i_flags & RTF_GATEWAY) &&
(!(dst_get_neighbour_raw(&rt->dst)->flags & NTF_ROUTER))) {
RT6_TRACE("purging route %p via non-router but gateway\n",
rt);
return -1;
}
gc_args.more++;
}
return 0;
}
In kernel 3.4, we have net/ipv6/ip6_fib.c:
static int fib6_age(struct rt6_info *rt, void *arg) {
unsigned long now = jiffies;
if (rt->rt6i_flags & RTF_EXPIRES && rt->dst.expires) {
if (time_after(now, rt->dst.expires)) {
RT6_TRACE("expiring %p\n", rt);
return -1;
}
gc_args.more++;
} else if (rt->rt6i_flags & RTF_CACHE) {
if (atomic_read(&rt->dst.__refcnt) == 0 &&
time_after_eq(now, rt->dst.lastuse + gc_args.timeout)) {
RT6_TRACE("aging clone %p\n", rt);
return -1;
} else if (rt->rt6i_flags & RTF_GATEWAY) {
struct neighbour *neigh;
__u8 neigh_flags = 0;
neigh = dst_neigh_lookup(&rt->dst, &rt->rt6i_gateway);
if (neigh) {
neigh_flags = neigh->flags;
neigh_release(neigh);
}
if (neigh_flags & NTF_ROUTER) {
RT6_TRACE("purging route %p via non-router but gateway\n",
rt);
return -1;
}
}
gc_args.more++;
}
return 0;
}
Do we have the meaning of the NTF_ROUTER flag reversed in kernel 3.4? Or is the opposite use of that flag a fix for the bug in the previous releases? Or is this a bug in kernel 3.4?
Also, could this remove a Gateway entry, if there is no neighbor entry for it (in any of the version of the code)? Could this try to deference a null pointer in 3.0.32 version of the code (and any version prior to 3.4)? In general, is this the right place to remove a gateway route that has __refcnt > 0?
I wish I had more expertise in this area of the code to answer questions and not only to pose them.
Thank you,
- Igor
^ permalink raw reply
* Re: [PATCH iproute2] Add reference to tc-codel(8) to the SEE ALSO section
From: Stephen Hemminger @ 2012-06-04 19:03 UTC (permalink / raw)
To: Jan Ceuleers; +Cc: andyqos, netdev
In-Reply-To: <1338666310-18744-1-git-send-email-jan.ceuleers@computer.org>
On Sat, 2 Jun 2012 21:45:10 +0200
Jan Ceuleers <jan.ceuleers@computer.org> wrote:
> Reported-by: Andy Furniss <andyqos@ukfsn.org>
> Signed-off-by: Jan Ceuleers <jan.ceuleers@computer.org>
> ---
> man/man8/tc.8 | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/man/man8/tc.8 b/man/man8/tc.8
> index 6576377..14a1cd8 100644
> --- a/man/man8/tc.8
> +++ b/man/man8/tc.8
> @@ -368,6 +368,7 @@ was written by Alexey N. Kuznetsov and added in Linux 2.2.
> .SH SEE ALSO
> .BR tc-cbq (8),
> .BR tc-choke (8),
> +.BR tc-codel (8),
> .BR tc-drr (8),
> .BR tc-htb (8),
> .BR tc-hfsc (8),
applied.
^ permalink raw reply
* tcp wifi upload performance and lots of ACKs
From: Ben Greear @ 2012-06-04 18:29 UTC (permalink / raw)
To: netdev
I'm going some TCP performance testing on wifi -> LAN interface connections. With
UDP, we can get around 250Mbps of payload throughput. With TCP, max is about 80Mbps.
I think the problem is that there are way too many ACK packets, and bi-directional
traffic on wifi interfaces really slows things down. (About 7000 pkts per second in
upload direction, 2000 pps download. And the vast majority of the download pkts
are 66 byte ACK pkts from what I can tell.)
Kernel is 3.3.7+
Anyone know of any tuning parameters that would let the receiving socket wait a
bit longer and send more ACK data in fewer packets?
Packet traces and other info available if anyone wants to take a look.
Thanks,
Ben
--
Ben Greear <greearb@candelatech.com>
Candela Technologies Inc http://www.candelatech.com
^ permalink raw reply
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