linux/include/net/sch_generic.h

807 lines
20 KiB

qdisc: bulk dequeue support for qdiscs with TCQ_F_ONETXQUEUE Based on DaveM's recent API work on dev_hard_start_xmit(), that allows sending/processing an entire skb list. This patch implements qdisc bulk dequeue, by allowing multiple packets to be dequeued in dequeue_skb(). The optimization principle for this is two fold, (1) to amortize locking cost and (2) avoid expensive tailptr update for notifying HW. (1) Several packets are dequeued while holding the qdisc root_lock, amortizing locking cost over several packet. The dequeued SKB list is processed under the TXQ lock in dev_hard_start_xmit(), thus also amortizing the cost of the TXQ lock. (2) Further more, dev_hard_start_xmit() will utilize the skb->xmit_more API to delay HW tailptr update, which also reduces the cost per packet. One restriction of the new API is that every SKB must belong to the same TXQ. This patch takes the easy way out, by restricting bulk dequeue to qdisc's with the TCQ_F_ONETXQUEUE flag, that specifies the qdisc only have attached a single TXQ. Some detail about the flow; dev_hard_start_xmit() will process the skb list, and transmit packets individually towards the driver (see xmit_one()). In case the driver stops midway in the list, the remaining skb list is returned by dev_hard_start_xmit(). In sch_direct_xmit() this returned list is requeued by dev_requeue_skb(). To avoid overshooting the HW limits, which results in requeuing, the patch limits the amount of bytes dequeued, based on the drivers BQL limits. In-effect bulking will only happen for BQL enabled drivers. Small amounts for extra HoL blocking (2x MTU/0.24ms) were measured at 100Mbit/s, with bulking 8 packets, but the oscillating nature of the measurement indicate something, like sched latency might be causing this effect. More comparisons show, that this oscillation goes away occationally. Thus, we disregard this artifact completely and remove any "magic" bulking limit. For now, as a conservative approach, stop bulking when seeing TSO and segmented GSO packets. They already benefit from bulking on their own. A followup patch add this, to allow easier bisect-ability for finding regressions. Jointed work with Hannes, Daniel and Florian. Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com> Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org> Signed-off-by: Daniel Borkmann <dborkman@redhat.com> Signed-off-by: Florian Westphal <fw@strlen.de> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-10-01 22:35:59 +02:00
net_sched: fix qdisc_tree_decrease_qlen() races qdisc_tree_decrease_qlen() suffers from two problems on multiqueue devices. One problem is that it updates sch->q.qlen and sch->qstats.drops on the mq/mqprio root qdisc, while it should not : Daniele reported underflows errors : [ 681.774821] PAX: sch->q.qlen: 0 n: 1 [ 681.774825] PAX: size overflow detected in function qdisc_tree_decrease_qlen net/sched/sch_api.c:769 cicus.693_49 min, count: 72, decl: qlen; num: 0; context: sk_buff_head; [ 681.774954] CPU: 2 PID: 19 Comm: ksoftirqd/2 Tainted: G O 4.2.6.201511282239-1-grsec #1 [ 681.774955] Hardware name: ASUSTeK COMPUTER INC. X302LJ/X302LJ, BIOS X302LJ.202 03/05/2015 [ 681.774956] ffffffffa9a04863 0000000000000000 0000000000000000 ffffffffa990ff7c [ 681.774959] ffffc90000d3bc38 ffffffffa95d2810 0000000000000007 ffffffffa991002b [ 681.774960] ffffc90000d3bc68 ffffffffa91a44f4 0000000000000001 0000000000000001 [ 681.774962] Call Trace: [ 681.774967] [<ffffffffa95d2810>] dump_stack+0x4c/0x7f [ 681.774970] [<ffffffffa91a44f4>] report_size_overflow+0x34/0x50 [ 681.774972] [<ffffffffa94d17e2>] qdisc_tree_decrease_qlen+0x152/0x160 [ 681.774976] [<ffffffffc02694b1>] fq_codel_dequeue+0x7b1/0x820 [sch_fq_codel] [ 681.774978] [<ffffffffc02680a0>] ? qdisc_peek_dequeued+0xa0/0xa0 [sch_fq_codel] [ 681.774980] [<ffffffffa94cd92d>] __qdisc_run+0x4d/0x1d0 [ 681.774983] [<ffffffffa949b2b2>] net_tx_action+0xc2/0x160 [ 681.774985] [<ffffffffa90664c1>] __do_softirq+0xf1/0x200 [ 681.774987] [<ffffffffa90665ee>] run_ksoftirqd+0x1e/0x30 [ 681.774989] [<ffffffffa90896b0>] smpboot_thread_fn+0x150/0x260 [ 681.774991] [<ffffffffa9089560>] ? sort_range+0x40/0x40 [ 681.774992] [<ffffffffa9085fe4>] kthread+0xe4/0x100 [ 681.774994] [<ffffffffa9085f00>] ? kthread_worker_fn+0x170/0x170 [ 681.774995] [<ffffffffa95d8d1e>] ret_from_fork+0x3e/0x70 mq/mqprio have their own ways to report qlen/drops by folding stats on all their queues, with appropriate locking. A second problem is that qdisc_tree_decrease_qlen() calls qdisc_lookup() without proper locking : concurrent qdisc updates could corrupt the list that qdisc_match_from_root() parses to find a qdisc given its handle. Fix first problem adding a TCQ_F_NOPARENT qdisc flag that qdisc_tree_decrease_qlen() can use to abort its tree traversal, as soon as it meets a mq/mqprio qdisc children. Second problem can be fixed by RCU protection. Qdisc are already freed after RCU grace period, so qdisc_list_add() and qdisc_list_del() simply have to use appropriate rcu list variants. A future patch will add a per struct netdev_queue list anchor, so that qdisc_tree_decrease_qlen() can have more efficient lookups. Reported-by: Daniele Fucini <dfucini@gmail.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Cong Wang <cwang@twopensource.com> Cc: Jamal Hadi Salim <jhs@mojatatu.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-12-01 20:08:51 -08:00
net: sched: fix panic in rate estimators Doing the following commands on a non idle network device panics the box instantly, because cpu_bstats gets overwritten by stats. tc qdisc add dev eth0 root <your_favorite_qdisc> ... some traffic (one packet is enough) ... tc qdisc replace dev eth0 root est 1sec 4sec <your_favorite_qdisc> [ 325.355596] BUG: unable to handle kernel paging request at ffff8841dc5a074c [ 325.362609] IP: [<ffffffff81541c9e>] __gnet_stats_copy_basic+0x3e/0x90 [ 325.369158] PGD 1fa7067 PUD 0 [ 325.372254] Oops: 0000 [#1] SMP [ 325.375514] Modules linked in: ... [ 325.398346] CPU: 13 PID: 14313 Comm: tc Not tainted 3.19.0-smp-DEV #1163 [ 325.412042] task: ffff8800793ab5d0 ti: ffff881ff2fa4000 task.ti: ffff881ff2fa4000 [ 325.419518] RIP: 0010:[<ffffffff81541c9e>] [<ffffffff81541c9e>] __gnet_stats_copy_basic+0x3e/0x90 [ 325.428506] RSP: 0018:ffff881ff2fa7928 EFLAGS: 00010286 [ 325.433824] RAX: 000000000000000c RBX: ffff881ff2fa796c RCX: 000000000000000c [ 325.440988] RDX: ffff8841dc5a0744 RSI: 0000000000000060 RDI: 0000000000000060 [ 325.448120] RBP: ffff881ff2fa7948 R08: ffffffff81cd4f80 R09: 0000000000000000 [ 325.455268] R10: ffff883ff223e400 R11: 0000000000000000 R12: 000000015cba0744 [ 325.462405] R13: ffffffff81cd4f80 R14: ffff883ff223e460 R15: ffff883feea0722c [ 325.469536] FS: 00007f2ee30fa700(0000) GS:ffff88407fa20000(0000) knlGS:0000000000000000 [ 325.477630] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 325.483380] CR2: ffff8841dc5a074c CR3: 0000003feeae9000 CR4: 00000000001407e0 [ 325.490510] Stack: [ 325.492524] ffff883feea0722c ffff883fef719dc0 ffff883feea0722c ffff883ff223e4a0 [ 325.499990] ffff881ff2fa79a8 ffffffff815424ee ffff883ff223e49c 000000015cba0744 [ 325.507460] 00000000f2fa7978 0000000000000000 ffff881ff2fa79a8 ffff883ff223e4a0 [ 325.514956] Call Trace: [ 325.517412] [<ffffffff815424ee>] gen_new_estimator+0x8e/0x230 [ 325.523250] [<ffffffff815427aa>] gen_replace_estimator+0x4a/0x60 [ 325.529349] [<ffffffff815718ab>] tc_modify_qdisc+0x52b/0x590 [ 325.535117] [<ffffffff8155edd0>] rtnetlink_rcv_msg+0xa0/0x240 [ 325.540963] [<ffffffff8155ed30>] ? __rtnl_unlock+0x20/0x20 [ 325.546532] [<ffffffff8157f811>] netlink_rcv_skb+0xb1/0xc0 [ 325.552145] [<ffffffff8155b355>] rtnetlink_rcv+0x25/0x40 [ 325.557558] [<ffffffff8157f0d8>] netlink_unicast+0x168/0x220 [ 325.563317] [<ffffffff8157f47c>] netlink_sendmsg+0x2ec/0x3e0 Lets play safe and not use an union : percpu 'pointers' are mostly read anyway, and we have typically few qdiscs per host. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: John Fastabend <john.fastabend@gmail.com> Fixes: 22e0f8b9322c ("net: sched: make bstats per cpu and estimator RCU safe") Signed-off-by: David S. Miller <davem@davemloft.net>
2015-01-29 17:30:12 -08:00
net: sched: fix panic in rate estimators Doing the following commands on a non idle network device panics the box instantly, because cpu_bstats gets overwritten by stats. tc qdisc add dev eth0 root <your_favorite_qdisc> ... some traffic (one packet is enough) ... tc qdisc replace dev eth0 root est 1sec 4sec <your_favorite_qdisc> [ 325.355596] BUG: unable to handle kernel paging request at ffff8841dc5a074c [ 325.362609] IP: [<ffffffff81541c9e>] __gnet_stats_copy_basic+0x3e/0x90 [ 325.369158] PGD 1fa7067 PUD 0 [ 325.372254] Oops: 0000 [#1] SMP [ 325.375514] Modules linked in: ... [ 325.398346] CPU: 13 PID: 14313 Comm: tc Not tainted 3.19.0-smp-DEV #1163 [ 325.412042] task: ffff8800793ab5d0 ti: ffff881ff2fa4000 task.ti: ffff881ff2fa4000 [ 325.419518] RIP: 0010:[<ffffffff81541c9e>] [<ffffffff81541c9e>] __gnet_stats_copy_basic+0x3e/0x90 [ 325.428506] RSP: 0018:ffff881ff2fa7928 EFLAGS: 00010286 [ 325.433824] RAX: 000000000000000c RBX: ffff881ff2fa796c RCX: 000000000000000c [ 325.440988] RDX: ffff8841dc5a0744 RSI: 0000000000000060 RDI: 0000000000000060 [ 325.448120] RBP: ffff881ff2fa7948 R08: ffffffff81cd4f80 R09: 0000000000000000 [ 325.455268] R10: ffff883ff223e400 R11: 0000000000000000 R12: 000000015cba0744 [ 325.462405] R13: ffffffff81cd4f80 R14: ffff883ff223e460 R15: ffff883feea0722c [ 325.469536] FS: 00007f2ee30fa700(0000) GS:ffff88407fa20000(0000) knlGS:0000000000000000 [ 325.477630] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 325.483380] CR2: ffff8841dc5a074c CR3: 0000003feeae9000 CR4: 00000000001407e0 [ 325.490510] Stack: [ 325.492524] ffff883feea0722c ffff883fef719dc0 ffff883feea0722c ffff883ff223e4a0 [ 325.499990] ffff881ff2fa79a8 ffffffff815424ee ffff883ff223e49c 000000015cba0744 [ 325.507460] 00000000f2fa7978 0000000000000000 ffff881ff2fa79a8 ffff883ff223e4a0 [ 325.514956] Call Trace: [ 325.517412] [<ffffffff815424ee>] gen_new_estimator+0x8e/0x230 [ 325.523250] [<ffffffff815427aa>] gen_replace_estimator+0x4a/0x60 [ 325.529349] [<ffffffff815718ab>] tc_modify_qdisc+0x52b/0x590 [ 325.535117] [<ffffffff8155edd0>] rtnetlink_rcv_msg+0xa0/0x240 [ 325.540963] [<ffffffff8155ed30>] ? __rtnl_unlock+0x20/0x20 [ 325.546532] [<ffffffff8157f811>] netlink_rcv_skb+0xb1/0xc0 [ 325.552145] [<ffffffff8155b355>] rtnetlink_rcv+0x25/0x40 [ 325.557558] [<ffffffff8157f0d8>] netlink_unicast+0x168/0x220 [ 325.563317] [<ffffffff8157f47c>] netlink_sendmsg+0x2ec/0x3e0 Lets play safe and not use an union : percpu 'pointers' are mostly read anyway, and we have typically few qdiscs per host. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: John Fastabend <john.fastabend@gmail.com> Fixes: 22e0f8b9322c ("net: sched: make bstats per cpu and estimator RCU safe") Signed-off-by: David S. Miller <davem@davemloft.net>
2015-01-29 17:30:12 -08:00
net: sched: fix panic in rate estimators Doing the following commands on a non idle network device panics the box instantly, because cpu_bstats gets overwritten by stats. tc qdisc add dev eth0 root <your_favorite_qdisc> ... some traffic (one packet is enough) ... tc qdisc replace dev eth0 root est 1sec 4sec <your_favorite_qdisc> [ 325.355596] BUG: unable to handle kernel paging request at ffff8841dc5a074c [ 325.362609] IP: [<ffffffff81541c9e>] __gnet_stats_copy_basic+0x3e/0x90 [ 325.369158] PGD 1fa7067 PUD 0 [ 325.372254] Oops: 0000 [#1] SMP [ 325.375514] Modules linked in: ... [ 325.398346] CPU: 13 PID: 14313 Comm: tc Not tainted 3.19.0-smp-DEV #1163 [ 325.412042] task: ffff8800793ab5d0 ti: ffff881ff2fa4000 task.ti: ffff881ff2fa4000 [ 325.419518] RIP: 0010:[<ffffffff81541c9e>] [<ffffffff81541c9e>] __gnet_stats_copy_basic+0x3e/0x90 [ 325.428506] RSP: 0018:ffff881ff2fa7928 EFLAGS: 00010286 [ 325.433824] RAX: 000000000000000c RBX: ffff881ff2fa796c RCX: 000000000000000c [ 325.440988] RDX: ffff8841dc5a0744 RSI: 0000000000000060 RDI: 0000000000000060 [ 325.448120] RBP: ffff881ff2fa7948 R08: ffffffff81cd4f80 R09: 0000000000000000 [ 325.455268] R10: ffff883ff223e400 R11: 0000000000000000 R12: 000000015cba0744 [ 325.462405] R13: ffffffff81cd4f80 R14: ffff883ff223e460 R15: ffff883feea0722c [ 325.469536] FS: 00007f2ee30fa700(0000) GS:ffff88407fa20000(0000) knlGS:0000000000000000 [ 325.477630] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 325.483380] CR2: ffff8841dc5a074c CR3: 0000003feeae9000 CR4: 00000000001407e0 [ 325.490510] Stack: [ 325.492524] ffff883feea0722c ffff883fef719dc0 ffff883feea0722c ffff883ff223e4a0 [ 325.499990] ffff881ff2fa79a8 ffffffff815424ee ffff883ff223e49c 000000015cba0744 [ 325.507460] 00000000f2fa7978 0000000000000000 ffff881ff2fa79a8 ffff883ff223e4a0 [ 325.514956] Call Trace: [ 325.517412] [<ffffffff815424ee>] gen_new_estimator+0x8e/0x230 [ 325.523250] [<ffffffff815427aa>] gen_replace_estimator+0x4a/0x60 [ 325.529349] [<ffffffff815718ab>] tc_modify_qdisc+0x52b/0x590 [ 325.535117] [<ffffffff8155edd0>] rtnetlink_rcv_msg+0xa0/0x240 [ 325.540963] [<ffffffff8155ed30>] ? __rtnl_unlock+0x20/0x20 [ 325.546532] [<ffffffff8157f811>] netlink_rcv_skb+0xb1/0xc0 [ 325.552145] [<ffffffff8155b355>] rtnetlink_rcv+0x25/0x40 [ 325.557558] [<ffffffff8157f0d8>] netlink_unicast+0x168/0x220 [ 325.563317] [<ffffffff8157f47c>] netlink_sendmsg+0x2ec/0x3e0 Lets play safe and not use an union : percpu 'pointers' are mostly read anyway, and we have typically few qdiscs per host. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: John Fastabend <john.fastabend@gmail.com> Fixes: 22e0f8b9322c ("net: sched: make bstats per cpu and estimator RCU safe") Signed-off-by: David S. Miller <davem@davemloft.net>
2015-01-29 17:30:12 -08:00
qdisc: bulk dequeue support for qdiscs with TCQ_F_ONETXQUEUE Based on DaveM's recent API work on dev_hard_start_xmit(), that allows sending/processing an entire skb list. This patch implements qdisc bulk dequeue, by allowing multiple packets to be dequeued in dequeue_skb(). The optimization principle for this is two fold, (1) to amortize locking cost and (2) avoid expensive tailptr update for notifying HW. (1) Several packets are dequeued while holding the qdisc root_lock, amortizing locking cost over several packet. The dequeued SKB list is processed under the TXQ lock in dev_hard_start_xmit(), thus also amortizing the cost of the TXQ lock. (2) Further more, dev_hard_start_xmit() will utilize the skb->xmit_more API to delay HW tailptr update, which also reduces the cost per packet. One restriction of the new API is that every SKB must belong to the same TXQ. This patch takes the easy way out, by restricting bulk dequeue to qdisc's with the TCQ_F_ONETXQUEUE flag, that specifies the qdisc only have attached a single TXQ. Some detail about the flow; dev_hard_start_xmit() will process the skb list, and transmit packets individually towards the driver (see xmit_one()). In case the driver stops midway in the list, the remaining skb list is returned by dev_hard_start_xmit(). In sch_direct_xmit() this returned list is requeued by dev_requeue_skb(). To avoid overshooting the HW limits, which results in requeuing, the patch limits the amount of bytes dequeued, based on the drivers BQL limits. In-effect bulking will only happen for BQL enabled drivers. Small amounts for extra HoL blocking (2x MTU/0.24ms) were measured at 100Mbit/s, with bulking 8 packets, but the oscillating nature of the measurement indicate something, like sched latency might be causing this effect. More comparisons show, that this oscillation goes away occationally. Thus, we disregard this artifact completely and remove any "magic" bulking limit. For now, as a conservative approach, stop bulking when seeing TSO and segmented GSO packets. They already benefit from bulking on their own. A followup patch add this, to allow easier bisect-ability for finding regressions. Jointed work with Hannes, Daniel and Florian. Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com> Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org> Signed-off-by: Daniel Borkmann <dborkman@redhat.com> Signed-off-by: Florian Westphal <fw@strlen.de> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-10-01 22:35:59 +02:00
bonding: Fix corrupted queue_mapping In the transmit path of the bonding driver, skb->cb is used to stash the skb->queue_mapping so that the bonding device can set its own queue mapping. This value becomes corrupted since the skb->cb is also used in __dev_xmit_skb. When transmitting through bonding driver, bond_select_queue is called from dev_queue_xmit. In bond_select_queue the original skb->queue_mapping is copied into skb->cb (via bond_queue_mapping) and skb->queue_mapping is overwritten with the bond driver queue. Subsequently in dev_queue_xmit, __dev_xmit_skb is called which writes the packet length into skb->cb, thereby overwriting the stashed queue mappping. In bond_dev_queue_xmit (called from hard_start_xmit), the queue mapping for the skb is set to the stashed value which is now the skb length and hence is an invalid queue for the slave device. If we want to save skb->queue_mapping into skb->cb[], best place is to add a field in struct qdisc_skb_cb, to make sure it wont conflict with other layers (eg : Qdiscc, Infiniband...) This patchs also makes sure (struct qdisc_skb_cb)->data is aligned on 8 bytes : netem qdisc for example assumes it can store an u64 in it, without misalignment penalty. Note : we only have 20 bytes left in (struct qdisc_skb_cb)->data[]. The largest user is CHOKe and it fills it. Based on a previous patch from Tom Herbert. Signed-off-by: Eric Dumazet <edumazet@google.com> Reported-by: Tom Herbert <therbert@google.com> Cc: John Fastabend <john.r.fastabend@intel.com> Cc: Roland Dreier <roland@kernel.org> Acked-by: Neil Horman <nhorman@tuxdriver.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2012-06-12 06:03:51 +00:00
net: Avoid enqueuing skb for default qdiscs dev_queue_xmit enqueue's a skb and calls qdisc_run which dequeue's the skb and xmits it. In most cases, the skb that is enqueue'd is the same one that is dequeue'd (unless the queue gets stopped or multiple cpu's write to the same queue and ends in a race with qdisc_run). For default qdiscs, we can remove the redundant enqueue/dequeue and simply xmit the skb since the default qdisc is work-conserving. The patch uses a new flag - TCQ_F_CAN_BYPASS to identify the default fast queue. The controversial part of the patch is incrementing qlen when a skb is requeued - this is to avoid checks like the second line below: + } else if ((q->flags & TCQ_F_CAN_BYPASS) && !qdisc_qlen(q) && >> !q->gso_skb && + !test_and_set_bit(__QDISC_STATE_RUNNING, &q->state)) { Results of a 2 hour testing for multiple netperf sessions (1, 2, 4, 8, 12 sessions on a 4 cpu system-X). The BW numbers are aggregate Mb/s across iterations tested with this version on System-X boxes with Chelsio 10gbps cards: ---------------------------------- Size | ORG BW NEW BW | ---------------------------------- 128K | 156964 159381 | 256K | 158650 162042 | ---------------------------------- Changes from ver1: 1. Move sch_direct_xmit declaration from sch_generic.h to pkt_sched.h 2. Update qdisc basic statistics for direct xmit path. 3. Set qlen to zero in qdisc_reset. 4. Changed some function names to more meaningful ones. Signed-off-by: Krishna Kumar <krkumar2@in.ibm.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2009-08-06 01:44:21 +00:00
hlist: drop the node parameter from iterators I'm not sure why, but the hlist for each entry iterators were conceived list_for_each_entry(pos, head, member) The hlist ones were greedy and wanted an extra parameter: hlist_for_each_entry(tpos, pos, head, member) Why did they need an extra pos parameter? I'm not quite sure. Not only they don't really need it, it also prevents the iterator from looking exactly like the list iterator, which is unfortunate. Besides the semantic patch, there was some manual work required: - Fix up the actual hlist iterators in linux/list.h - Fix up the declaration of other iterators based on the hlist ones. - A very small amount of places were using the 'node' parameter, this was modified to use 'obj->member' instead. - Coccinelle didn't handle the hlist_for_each_entry_safe iterator properly, so those had to be fixed up manually. The semantic patch which is mostly the work of Peter Senna Tschudin is here: @@ iterator name hlist_for_each_entry, hlist_for_each_entry_continue, hlist_for_each_entry_from, hlist_for_each_entry_rcu, hlist_for_each_entry_rcu_bh, hlist_for_each_entry_continue_rcu_bh, for_each_busy_worker, ax25_uid_for_each, ax25_for_each, inet_bind_bucket_for_each, sctp_for_each_hentry, sk_for_each, sk_for_each_rcu, sk_for_each_from, sk_for_each_safe, sk_for_each_bound, hlist_for_each_entry_safe, hlist_for_each_entry_continue_rcu, nr_neigh_for_each, nr_neigh_for_each_safe, nr_node_for_each, nr_node_for_each_safe, for_each_gfn_indirect_valid_sp, for_each_gfn_sp, for_each_host; type T; expression a,c,d,e; identifier b; statement S; @@ -T b; <+... when != b ( hlist_for_each_entry(a, - b, c, d) S | hlist_for_each_entry_continue(a, - b, c) S | hlist_for_each_entry_from(a, - b, c) S | hlist_for_each_entry_rcu(a, - b, c, d) S | hlist_for_each_entry_rcu_bh(a, - b, c, d) S | hlist_for_each_entry_continue_rcu_bh(a, - b, c) S | for_each_busy_worker(a, c, - b, d) S | ax25_uid_for_each(a, - b, c) S | ax25_for_each(a, - b, c) S | inet_bind_bucket_for_each(a, - b, c) S | sctp_for_each_hentry(a, - b, c) S | sk_for_each(a, - b, c) S | sk_for_each_rcu(a, - b, c) S | sk_for_each_from -(a, b) +(a) S + sk_for_each_from(a) S | sk_for_each_safe(a, - b, c, d) S | sk_for_each_bound(a, - b, c) S | hlist_for_each_entry_safe(a, - b, c, d, e) S | hlist_for_each_entry_continue_rcu(a, - b, c) S | nr_neigh_for_each(a, - b, c) S | nr_neigh_for_each_safe(a, - b, c, d) S | nr_node_for_each(a, - b, c) S | nr_node_for_each_safe(a, - b, c, d) S | - for_each_gfn_sp(a, c, d, b) S + for_each_gfn_sp(a, c, d) S | - for_each_gfn_indirect_valid_sp(a, c, d, b) S + for_each_gfn_indirect_valid_sp(a, c, d) S | for_each_host(a, - b, c) S | for_each_host_safe(a, - b, c, d) S | for_each_mesh_entry(a, - b, c, d) S ) ...+> [akpm@linux-foundation.org: drop bogus change from net/ipv4/raw.c] [akpm@linux-foundation.org: drop bogus hunk from net/ipv6/raw.c] [akpm@linux-foundation.org: checkpatch fixes] [akpm@linux-foundation.org: fix warnings] [akpm@linux-foudnation.org: redo intrusive kvm changes] Tested-by: Peter Senna Tschudin <peter.senna@gmail.com> Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Signed-off-by: Sasha Levin <sasha.levin@oracle.com> Cc: Wu Fengguang <fengguang.wu@intel.com> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: Gleb Natapov <gleb@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-02-27 17:06:00 -08:00
2015-09-15 23:05:43 -07:00
net: Avoid enqueuing skb for default qdiscs dev_queue_xmit enqueue's a skb and calls qdisc_run which dequeue's the skb and xmits it. In most cases, the skb that is enqueue'd is the same one that is dequeue'd (unless the queue gets stopped or multiple cpu's write to the same queue and ends in a race with qdisc_run). For default qdiscs, we can remove the redundant enqueue/dequeue and simply xmit the skb since the default qdisc is work-conserving. The patch uses a new flag - TCQ_F_CAN_BYPASS to identify the default fast queue. The controversial part of the patch is incrementing qlen when a skb is requeued - this is to avoid checks like the second line below: + } else if ((q->flags & TCQ_F_CAN_BYPASS) && !qdisc_qlen(q) && >> !q->gso_skb && + !test_and_set_bit(__QDISC_STATE_RUNNING, &q->state)) { Results of a 2 hour testing for multiple netperf sessions (1, 2, 4, 8, 12 sessions on a 4 cpu system-X). The BW numbers are aggregate Mb/s across iterations tested with this version on System-X boxes with Chelsio 10gbps cards: ---------------------------------- Size | ORG BW NEW BW | ---------------------------------- 128K | 156964 159381 | 256K | 158650 162042 | ---------------------------------- Changes from ver1: 1. Move sch_direct_xmit declaration from sch_generic.h to pkt_sched.h 2. Update qdisc basic statistics for direct xmit path. 3. Set qlen to zero in qdisc_reset. 4. Changed some function names to more meaningful ones. Signed-off-by: Krishna Kumar <krkumar2@in.ibm.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2009-08-06 01:44:21 +00:00
net: Avoid enqueuing skb for default qdiscs dev_queue_xmit enqueue's a skb and calls qdisc_run which dequeue's the skb and xmits it. In most cases, the skb that is enqueue'd is the same one that is dequeue'd (unless the queue gets stopped or multiple cpu's write to the same queue and ends in a race with qdisc_run). For default qdiscs, we can remove the redundant enqueue/dequeue and simply xmit the skb since the default qdisc is work-conserving. The patch uses a new flag - TCQ_F_CAN_BYPASS to identify the default fast queue. The controversial part of the patch is incrementing qlen when a skb is requeued - this is to avoid checks like the second line below: + } else if ((q->flags & TCQ_F_CAN_BYPASS) && !qdisc_qlen(q) && >> !q->gso_skb && + !test_and_set_bit(__QDISC_STATE_RUNNING, &q->state)) { Results of a 2 hour testing for multiple netperf sessions (1, 2, 4, 8, 12 sessions on a 4 cpu system-X). The BW numbers are aggregate Mb/s across iterations tested with this version on System-X boxes with Chelsio 10gbps cards: ---------------------------------- Size | ORG BW NEW BW | ---------------------------------- 128K | 156964 159381 | 256K | 158650 162042 | ---------------------------------- Changes from ver1: 1. Move sch_direct_xmit declaration from sch_generic.h to pkt_sched.h 2. Update qdisc basic statistics for direct xmit path. 3. Set qlen to zero in qdisc_reset. 4. Changed some function names to more meaningful ones. Signed-off-by: Krishna Kumar <krkumar2@in.ibm.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2009-08-06 01:44:21 +00:00