Re: [PATCH v2 net-next] softirq: reduce latencies
From: Joe Perches
Date: Fri Jan 04 2013 - 03:15:43 EST
On Thu, 2013-01-03 at 23:49 -0800, Eric Dumazet wrote:
> In various network workloads, __do_softirq() latencies can be up
> to 20 ms if HZ=1000, and 200 ms if HZ=100.
> This patch changes the fallback to ksoftirqd condition to :
> - A time limit of 2 ms.
> diff --git a/kernel/softirq.c b/kernel/softirq.c
> +#define MAX_SOFTIRQ_TIME max(1, (2*HZ/1000))
And if HZ is 10000?
> asmlinkage void __do_softirq(void)
> + unsigned long end = jiffies + MAX_SOFTIRQ_TIME;
Perhaps MAX_SOFTIRQ_TIME should be
#define MAX_SOFTIRQ_TIME msecs_to_jiffies(2)
though it would be nicer if it were a compile time constant.
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