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

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Message-ID: <CA+icZUW+pvysyTKxaeO=1t1yXGHbSvLjViYnPHoz-osykuVq+w@mail.gmail.com>
Date:	Sat, 5 Jan 2013 09:58:16 +0100
From:	Sedat Dilek <sedat.dilek@...il.com>
To:	Eric Dumazet <eric.dumazet@...il.com>
Cc:	David Miller <davem@...emloft.net>, netdev@...r.kernel.org,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 net-next] softirq: reduce latencies

[ QUOTE ]

From: Eric Dumazet <eric.dumazet@...il.com>
Date: Thu, 03 Jan 2013 23:49:40 -0800

> From: Eric Dumazet <edumazet@...gle.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@...gle.com>

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

[ /QUOTE ]

Tested-by: Sedat Dilek <sedat.dilek@...il.com> (against Linux v3.8-rc2)
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