On Fri, 2013-01-04 at 00:15 -0800, Joe Perches wrote: > 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? >
Then its OK. 2*10000/1000 -> 20 ticks -> 2 ms > > 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. If you send a patch to convert msecs_to_jiffies() to an inline function when HZ = 1000, I will gladly use it instead of (2*HZ/1000) Right now, max(1, msecs_to_jiffies(2)) uses way too many instructions, while it should be the constant 2, known at compile time. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/