Re: [PATCH v2 net-next] softirq: reduce latencies
From: Joe Perches <joe@perches.com>
Date: 2013-01-04 08:15:54
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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.
[]
quoted hunk ↗ jump to hunk
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.