Re: [PATCH v2 net-next] softirq: reduce latencies

From: Eric Dumazet <redacted>
Date: Thu, 03 Jan 2013 23:49:40 -0800

From: Eric Dumazet <edumazet@google.com>

In various network workloads, __do_softirq() latencies can be up
to 20 ms if HZ=1000, and 200 ms if HZ=100.

This is because we iterate 10 times in the softirq dispatcher,
and some actions can consume a lot of cycles.

This patch changes the fallback to ksoftirqd condition to :

- A time limit of 2 ms.
- need_resched() being set on current task

When one of this condition is met, we wakeup ksoftirqd for further
softirq processing if we still have pending softirqs.

 ...

Signed-off-by: Eric Dumazet <edumazet@google.com>

Acked-by: David S. Miller <davem@davemloft.net>