* [PATCH net 1/3] s390/qeth: fix thinko in IPv4 multicast address tracking
2017-12-01 9:14 [PATCH net 0/3] s390/qeth: fixes 2017-12-01 Julian Wiedmann
@ 2017-12-01 9:14 ` Julian Wiedmann
2017-12-01 9:14 ` [PATCH net 2/3] s390/qeth: fix GSO throughput regression Julian Wiedmann
` (2 subsequent siblings)
3 siblings, 0 replies; 5+ messages in thread
From: Julian Wiedmann @ 2017-12-01 9:14 UTC (permalink / raw)
To: David Miller
Cc: netdev, linux-s390, Martin Schwidefsky, Heiko Carstens,
Stefan Raspl, Ursula Braun, Julian Wiedmann
Commit 5f78e29ceebf ("qeth: optimize IP handling in rx_mode callback")
reworked how secondary addresses are managed for qeth devices.
Instead of dropping & subsequently re-adding all addresses on every
ndo_set_rx_mode() call, qeth now keeps track of the addresses that are
currently registered with the HW.
On a ndo_set_rx_mode(), we thus only need to do (de-)registration
requests for the addresses that have actually changed.
On L3 devices, the lookup for IPv4 Multicast addresses checks the wrong
hashtable - and thus never finds a match. As a result, we first delete
*all* such addresses, and then re-add them again. So each set_rx_mode()
causes a short period where the IPv4 Multicast addresses are not
registered, and the card stops forwarding inbound traffic for them.
Fix this by setting the ->is_multicast flag on the lookup object, thus
enabling qeth_l3_ip_from_hash() to search the correct hashtable and
find a match there.
Fixes: 5f78e29ceebf ("qeth: optimize IP handling in rx_mode callback")
Signed-off-by: Julian Wiedmann <jwi@linux.vnet.ibm.com>
---
drivers/s390/net/qeth_l3_main.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/drivers/s390/net/qeth_l3_main.c b/drivers/s390/net/qeth_l3_main.c
index aadd384316a3..e79936b50698 100644
--- a/drivers/s390/net/qeth_l3_main.c
+++ b/drivers/s390/net/qeth_l3_main.c
@@ -1376,6 +1376,7 @@ qeth_l3_add_mc_to_hash(struct qeth_card *card, struct in_device *in4_dev)
tmp->u.a4.addr = be32_to_cpu(im4->multiaddr);
memcpy(tmp->mac, buf, sizeof(tmp->mac));
+ tmp->is_multicast = 1;
ipm = qeth_l3_ip_from_hash(card, tmp);
if (ipm) {
--
2.13.5
^ permalink raw reply related [flat|nested] 5+ messages in thread* [PATCH net 2/3] s390/qeth: fix GSO throughput regression
2017-12-01 9:14 [PATCH net 0/3] s390/qeth: fixes 2017-12-01 Julian Wiedmann
2017-12-01 9:14 ` [PATCH net 1/3] s390/qeth: fix thinko in IPv4 multicast address tracking Julian Wiedmann
@ 2017-12-01 9:14 ` Julian Wiedmann
2017-12-01 9:14 ` [PATCH net 3/3] s390/qeth: build max size GSO skbs on L2 devices Julian Wiedmann
2017-12-03 2:35 ` [PATCH net 0/3] s390/qeth: fixes 2017-12-01 David Miller
3 siblings, 0 replies; 5+ messages in thread
From: Julian Wiedmann @ 2017-12-01 9:14 UTC (permalink / raw)
To: David Miller
Cc: netdev, linux-s390, Martin Schwidefsky, Heiko Carstens,
Stefan Raspl, Ursula Braun, Julian Wiedmann
Using GSO with small MTUs currently results in a substantial throughput
regression - which is caused by how qeth needs to map non-linear skbs
into its IO buffer elements:
compared to a linear skb, each GSO-segmented skb effectively consumes
twice as many buffer elements (ie two instead of one) due to the
additional header-only part. This causes the Output Queue to be
congested with low-utilized IO buffers.
Fix this as follows:
If the MSS is low enough so that a non-SG GSO segmentation produces
order-0 skbs (currently ~3500 byte), opt out from NETIF_F_SG. This is
where we anticipate the biggest savings, since an SG-enabled
GSO segmentation produces skbs that always consume at least two
buffer elements.
Larger MSS values continue to get a SG-enabled GSO segmentation, since
1) the relative overhead of the additional header-only buffer element
becomes less noticeable, and
2) the linearization overhead increases.
With the throughput regression fixed, re-enable NETIF_F_SG by default to
reap the significant CPU savings of GSO.
Fixes: 5722963a8e83 ("qeth: do not turn on SG per default")
Reported-by: Nils Hoppmann <niho@de.ibm.com>
Signed-off-by: Julian Wiedmann <jwi@linux.vnet.ibm.com>
---
drivers/s390/net/qeth_core.h | 3 +++
drivers/s390/net/qeth_core_main.c | 31 +++++++++++++++++++++++++++++++
drivers/s390/net/qeth_l2_main.c | 2 ++
drivers/s390/net/qeth_l3_main.c | 2 ++
4 files changed, 38 insertions(+)
diff --git a/drivers/s390/net/qeth_core.h b/drivers/s390/net/qeth_core.h
index 9cd569ef43ec..15015a24f8ad 100644
--- a/drivers/s390/net/qeth_core.h
+++ b/drivers/s390/net/qeth_core.h
@@ -987,6 +987,9 @@ struct qeth_cmd_buffer *qeth_get_setassparms_cmd(struct qeth_card *,
int qeth_set_features(struct net_device *, netdev_features_t);
void qeth_recover_features(struct net_device *dev);
netdev_features_t qeth_fix_features(struct net_device *, netdev_features_t);
+netdev_features_t qeth_features_check(struct sk_buff *skb,
+ struct net_device *dev,
+ netdev_features_t features);
int qeth_vm_request_mac(struct qeth_card *card);
int qeth_push_hdr(struct sk_buff *skb, struct qeth_hdr **hdr, unsigned int len);
diff --git a/drivers/s390/net/qeth_core_main.c b/drivers/s390/net/qeth_core_main.c
index 49b9efeba1bd..d9b0e07d4fa7 100644
--- a/drivers/s390/net/qeth_core_main.c
+++ b/drivers/s390/net/qeth_core_main.c
@@ -19,6 +19,11 @@
#include <linux/mii.h>
#include <linux/kthread.h>
#include <linux/slab.h>
+#include <linux/if_vlan.h>
+#include <linux/netdevice.h>
+#include <linux/netdev_features.h>
+#include <linux/skbuff.h>
+
#include <net/iucv/af_iucv.h>
#include <net/dsfield.h>
@@ -6438,6 +6443,32 @@ netdev_features_t qeth_fix_features(struct net_device *dev,
}
EXPORT_SYMBOL_GPL(qeth_fix_features);
+netdev_features_t qeth_features_check(struct sk_buff *skb,
+ struct net_device *dev,
+ netdev_features_t features)
+{
+ /* GSO segmentation builds skbs with
+ * a (small) linear part for the headers, and
+ * page frags for the data.
+ * Compared to a linear skb, the header-only part consumes an
+ * additional buffer element. This reduces buffer utilization, and
+ * hurts throughput. So compress small segments into one element.
+ */
+ if (netif_needs_gso(skb, features)) {
+ /* match skb_segment(): */
+ unsigned int doffset = skb->data - skb_mac_header(skb);
+ unsigned int hsize = skb_shinfo(skb)->gso_size;
+ unsigned int hroom = skb_headroom(skb);
+
+ /* linearize only if resulting skb allocations are order-0: */
+ if (SKB_DATA_ALIGN(hroom + doffset + hsize) <= SKB_MAX_HEAD(0))
+ features &= ~NETIF_F_SG;
+ }
+
+ return vlan_features_check(skb, features);
+}
+EXPORT_SYMBOL_GPL(qeth_features_check);
+
static int __init qeth_core_init(void)
{
int rc;
diff --git a/drivers/s390/net/qeth_l2_main.c b/drivers/s390/net/qeth_l2_main.c
index d2537c09126d..85162712d207 100644
--- a/drivers/s390/net/qeth_l2_main.c
+++ b/drivers/s390/net/qeth_l2_main.c
@@ -960,6 +960,7 @@ static const struct net_device_ops qeth_l2_netdev_ops = {
.ndo_stop = qeth_l2_stop,
.ndo_get_stats = qeth_get_stats,
.ndo_start_xmit = qeth_l2_hard_start_xmit,
+ .ndo_features_check = qeth_features_check,
.ndo_validate_addr = eth_validate_addr,
.ndo_set_rx_mode = qeth_l2_set_rx_mode,
.ndo_do_ioctl = qeth_do_ioctl,
@@ -1010,6 +1011,7 @@ static int qeth_l2_setup_netdev(struct qeth_card *card)
if (card->info.type == QETH_CARD_TYPE_OSD && !card->info.guestlan) {
card->dev->hw_features = NETIF_F_SG;
card->dev->vlan_features = NETIF_F_SG;
+ card->dev->features |= NETIF_F_SG;
/* OSA 3S and earlier has no RX/TX support */
if (qeth_is_supported(card, IPA_OUTBOUND_CHECKSUM)) {
card->dev->hw_features |= NETIF_F_IP_CSUM;
diff --git a/drivers/s390/net/qeth_l3_main.c b/drivers/s390/net/qeth_l3_main.c
index e79936b50698..46a841258fc8 100644
--- a/drivers/s390/net/qeth_l3_main.c
+++ b/drivers/s390/net/qeth_l3_main.c
@@ -2918,6 +2918,7 @@ static const struct net_device_ops qeth_l3_osa_netdev_ops = {
.ndo_stop = qeth_l3_stop,
.ndo_get_stats = qeth_get_stats,
.ndo_start_xmit = qeth_l3_hard_start_xmit,
+ .ndo_features_check = qeth_features_check,
.ndo_validate_addr = eth_validate_addr,
.ndo_set_rx_mode = qeth_l3_set_multicast_list,
.ndo_do_ioctl = qeth_do_ioctl,
@@ -2958,6 +2959,7 @@ static int qeth_l3_setup_netdev(struct qeth_card *card)
card->dev->vlan_features = NETIF_F_SG |
NETIF_F_RXCSUM | NETIF_F_IP_CSUM |
NETIF_F_TSO;
+ card->dev->features |= NETIF_F_SG;
}
}
} else if (card->info.type == QETH_CARD_TYPE_IQD) {
--
2.13.5
^ permalink raw reply related [flat|nested] 5+ messages in thread* [PATCH net 3/3] s390/qeth: build max size GSO skbs on L2 devices
2017-12-01 9:14 [PATCH net 0/3] s390/qeth: fixes 2017-12-01 Julian Wiedmann
2017-12-01 9:14 ` [PATCH net 1/3] s390/qeth: fix thinko in IPv4 multicast address tracking Julian Wiedmann
2017-12-01 9:14 ` [PATCH net 2/3] s390/qeth: fix GSO throughput regression Julian Wiedmann
@ 2017-12-01 9:14 ` Julian Wiedmann
2017-12-03 2:35 ` [PATCH net 0/3] s390/qeth: fixes 2017-12-01 David Miller
3 siblings, 0 replies; 5+ messages in thread
From: Julian Wiedmann @ 2017-12-01 9:14 UTC (permalink / raw)
To: David Miller
Cc: netdev, linux-s390, Martin Schwidefsky, Heiko Carstens,
Stefan Raspl, Ursula Braun, Julian Wiedmann
The current GSO skb size limit was copy&pasted over from the L3 path,
where it is needed due to a TSO limitation.
As L2 devices don't offer TSO support (and thus all GSO skbs are
segmented before they reach the driver), there's no reason to restrict
the stack in how large it may build the GSO skbs.
Fixes: d52aec97e5bc ("qeth: enable scatter/gather in layer 2 mode")
Signed-off-by: Julian Wiedmann <jwi@linux.vnet.ibm.com>
---
drivers/s390/net/qeth_l2_main.c | 2 --
drivers/s390/net/qeth_l3_main.c | 4 ++--
2 files changed, 2 insertions(+), 4 deletions(-)
diff --git a/drivers/s390/net/qeth_l2_main.c b/drivers/s390/net/qeth_l2_main.c
index 85162712d207..f21c94810373 100644
--- a/drivers/s390/net/qeth_l2_main.c
+++ b/drivers/s390/net/qeth_l2_main.c
@@ -1030,8 +1030,6 @@ static int qeth_l2_setup_netdev(struct qeth_card *card)
card->info.broadcast_capable = 1;
qeth_l2_request_initial_mac(card);
- card->dev->gso_max_size = (QETH_MAX_BUFFER_ELEMENTS(card) - 1) *
- PAGE_SIZE;
SET_NETDEV_DEV(card->dev, &card->gdev->dev);
netif_napi_add(card->dev, &card->napi, qeth_poll, QETH_NAPI_WEIGHT);
netif_carrier_off(card->dev);
diff --git a/drivers/s390/net/qeth_l3_main.c b/drivers/s390/net/qeth_l3_main.c
index 46a841258fc8..2a25f20566d8 100644
--- a/drivers/s390/net/qeth_l3_main.c
+++ b/drivers/s390/net/qeth_l3_main.c
@@ -2987,8 +2987,8 @@ static int qeth_l3_setup_netdev(struct qeth_card *card)
NETIF_F_HW_VLAN_CTAG_RX |
NETIF_F_HW_VLAN_CTAG_FILTER;
netif_keep_dst(card->dev);
- card->dev->gso_max_size = (QETH_MAX_BUFFER_ELEMENTS(card) - 1) *
- PAGE_SIZE;
+ netif_set_gso_max_size(card->dev, (QETH_MAX_BUFFER_ELEMENTS(card) - 1) *
+ PAGE_SIZE);
SET_NETDEV_DEV(card->dev, &card->gdev->dev);
netif_napi_add(card->dev, &card->napi, qeth_poll, QETH_NAPI_WEIGHT);
--
2.13.5
^ permalink raw reply related [flat|nested] 5+ messages in thread