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net: optimize napi_schedule_rps()

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Based on initial patch from Jason Xing.

Idea is to not raise NET_RX_SOFTIRQ from napi_schedule_rps()
when we queued a packet into another cpu backlog.

We can do this only in the context of us being called indirectly
from net_rx_action(), to have the guarantee our rps_ipi_list
will be processed before we exit from net_rx_action().

Link: https://lore.kernel.org/lkml/20230325152417.5403-1-kerneljasonxing@gmail.com/
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Jason Xing <kernelxing@tencent.com>
Reviewed-by: Jason Xing <kerneljasonxing@gmail.com>
Tested-by: Jason Xing <kerneljasonxing@gmail.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
This commit is contained in:
Eric Dumazet 2023-03-28 23:50:20 +00:00 committed by Paolo Abeni
parent c59647c0dc
commit 821eba962d
1 changed files with 5 additions and 3 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

6
net/core/dev.c
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@ -4587,8 +4587,6 @@ static void trigger_rx_softirq(void *data)
* *
* - If this is another cpu queue, link it to our rps_ipi_list, * - If this is another cpu queue, link it to our rps_ipi_list,
* and make sure we will process rps_ipi_list from net_rx_action(). * and make sure we will process rps_ipi_list from net_rx_action().
* As we do not know yet if we are called from net_rx_action(),
* we have to raise NET_RX_SOFTIRQ. This might change in the future.
* *
* - If this is our own queue, NAPI schedule our backlog. * - If this is our own queue, NAPI schedule our backlog.
* Note that this also raises NET_RX_SOFTIRQ. * Note that this also raises NET_RX_SOFTIRQ.
@ -4602,6 +4600,10 @@ static void napi_schedule_rps(struct softnet_data *sd)
sd->rps_ipi_next = mysd->rps_ipi_list; sd->rps_ipi_next = mysd->rps_ipi_list;
mysd->rps_ipi_list = sd; mysd->rps_ipi_list = sd;
/* If not called from net_rx_action()
* we have to raise NET_RX_SOFTIRQ.
*/
if (!mysd->in_net_rx_action)
__raise_softirq_irqoff(NET_RX_SOFTIRQ); __raise_softirq_irqoff(NET_RX_SOFTIRQ);
return; return;
} }