* [PATCH] f_phonet: use page-sized rather than MTU-sized RX buffers
2009-08-07 7:56 [PATCH] f_phonet: lock-less MTU change Rémi Denis-Courmont
@ 2009-08-07 7:56 ` Rémi Denis-Courmont
2009-08-13 5:15 ` David Miller
2009-08-13 5:15 ` [PATCH] f_phonet: lock-less MTU change David Miller
1 sibling, 1 reply; 4+ messages in thread
From: Rémi Denis-Courmont @ 2009-08-07 7:56 UTC (permalink / raw)
To: netdev
From: Rémi Denis-Courmont <remi.denis-courmont@nokia.com>
Instead of a large (physically) linear buffer, we generate a set of
paged sk_buff, so no extra memory copy is involved. This removes
high-order allocations and saves quite a bit of memory. Phonet MTU is
65541 bytes, so the two buffers were padded to 128 kilo-bytes each.
Now, we create 17 page buffers, almost a 75% memory use reduction.
Signed-off-by: Rémi Denis-Courmont <remi.denis-courmont@nokia.com>
---
drivers/usb/gadget/f_phonet.c | 77 +++++++++++++++++++++++++++--------------
1 files changed, 51 insertions(+), 26 deletions(-)
diff --git a/drivers/usb/gadget/f_phonet.c b/drivers/usb/gadget/f_phonet.c
index f4eff7c..d2de10b 100644
--- a/drivers/usb/gadget/f_phonet.c
+++ b/drivers/usb/gadget/f_phonet.c
@@ -35,6 +35,10 @@
#include "u_phonet.h"
#define PN_MEDIA_USB 0x1B
+#define MAXPACKET 512
+#if (PAGE_SIZE % MAXPACKET)
+#error MAXPACKET must divide PAGE_SIZE!
+#endif
/*-------------------------------------------------------------------------*/
@@ -45,6 +49,10 @@ struct phonet_port {
struct f_phonet {
struct usb_function function;
+ struct {
+ struct sk_buff *skb;
+ spinlock_t lock;
+ } rx;
struct net_device *dev;
struct usb_ep *in_ep, *out_ep;
@@ -52,7 +60,7 @@ struct f_phonet {
struct usb_request *out_reqv[0];
};
-static int phonet_rxq_size = 2;
+static int phonet_rxq_size = 17;
static inline struct f_phonet *func_to_pn(struct usb_function *f)
{
@@ -138,7 +146,7 @@ pn_hs_sink_desc = {
.bEndpointAddress = USB_DIR_OUT,
.bmAttributes = USB_ENDPOINT_XFER_BULK,
- .wMaxPacketSize = cpu_to_le16(512),
+ .wMaxPacketSize = cpu_to_le16(MAXPACKET),
};
static struct usb_endpoint_descriptor
@@ -298,21 +306,21 @@ static void pn_net_setup(struct net_device *dev)
static int
pn_rx_submit(struct f_phonet *fp, struct usb_request *req, gfp_t gfp_flags)
{
- struct sk_buff *skb;
- const size_t size = fp->dev->mtu;
+ struct net_device *dev = fp->dev;
+ struct page *page;
int err;
- skb = alloc_skb(size, gfp_flags);
- if (!skb)
+ page = __netdev_alloc_page(dev, gfp_flags);
+ if (!page)
return -ENOMEM;
- req->buf = skb->data;
- req->length = size;
- req->context = skb;
+ req->buf = page_address(page);
+ req->length = PAGE_SIZE;
+ req->context = page;
err = usb_ep_queue(fp->out_ep, req, gfp_flags);
if (unlikely(err))
- dev_kfree_skb_any(skb);
+ netdev_free_page(dev, page);
return err;
}
@@ -320,25 +328,37 @@ static void pn_rx_complete(struct usb_ep *ep, struct usb_request *req)
{
struct f_phonet *fp = ep->driver_data;
struct net_device *dev = fp->dev;
- struct sk_buff *skb = req->context;
+ struct page *page = req->context;
+ struct sk_buff *skb;
+ unsigned long flags;
int status = req->status;
switch (status) {
case 0:
- if (unlikely(!netif_running(dev)))
- break;
- if (unlikely(req->actual < 1))
+ spin_lock_irqsave(&fp->rx.lock, flags);
+ skb = fp->rx.skb;
+ if (!skb)
+ skb = fp->rx.skb = netdev_alloc_skb(dev, 12);
+ if (req->actual < req->length) /* Last fragment */
+ fp->rx.skb = NULL;
+ spin_unlock_irqrestore(&fp->rx.lock, flags);
+
+ if (unlikely(!skb))
break;
- skb_put(skb, req->actual);
- skb->protocol = htons(ETH_P_PHONET);
- skb_reset_mac_header(skb);
- __skb_pull(skb, 1);
- skb->dev = dev;
- dev->stats.rx_packets++;
- dev->stats.rx_bytes += skb->len;
-
- netif_rx(skb);
- skb = NULL;
+ skb_add_rx_frag(skb, skb_shinfo(skb)->nr_frags, page, 0,
+ req->actual);
+ page = NULL;
+
+ if (req->actual < req->length) { /* Last fragment */
+ skb->protocol = htons(ETH_P_PHONET);
+ skb_reset_mac_header(skb);
+ pskb_pull(skb, 1);
+ skb->dev = dev;
+ dev->stats.rx_packets++;
+ dev->stats.rx_bytes += skb->len;
+
+ netif_rx(skb);
+ }
break;
/* Do not resubmit in these cases: */
@@ -356,8 +376,8 @@ static void pn_rx_complete(struct usb_ep *ep, struct usb_request *req)
break;
}
- if (skb)
- dev_kfree_skb_any(skb);
+ if (page)
+ netdev_free_page(dev, page);
if (req)
pn_rx_submit(fp, req, GFP_ATOMIC);
}
@@ -375,6 +395,10 @@ static void __pn_reset(struct usb_function *f)
usb_ep_disable(fp->out_ep);
usb_ep_disable(fp->in_ep);
+ if (fp->rx.skb) {
+ dev_kfree_skb_irq(fp->rx.skb);
+ fp->rx.skb = NULL;
+ }
}
static int pn_set_alt(struct usb_function *f, unsigned intf, unsigned alt)
@@ -573,6 +597,7 @@ int __init phonet_bind_config(struct usb_configuration *c)
fp->function.set_alt = pn_set_alt;
fp->function.get_alt = pn_get_alt;
fp->function.disable = pn_disconnect;
+ spin_lock_init(&fp->rx.lock);
err = usb_add_function(c, &fp->function);
if (err)
--
1.6.0.4
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