Messages in this thread Patch in this message | | | Subject | [RFT][PATCH] sched: scale sysctl_sched_shares_ratelimit with nr_cpus | From | Peter Zijlstra <> | Date | Wed, 30 Jul 2008 12:27:55 +0200 |
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[And now with proper lkml address - so much for auto-add address entries]
Dhaval, Vatsa,
Could you guys give this patch a spin on the big iron and possibly tune the default shares_ratelimit value to give satisfactory fairness on your large machines while considering the overhead?
--- Subject: sched: scale sysctl_sched_shares_ratelimit with nr_cpus
David reported that his Niagra spend a little too much time in tg_shares_up(), which considering he has a large cpu count makes sense.
So scale the ratelimit value with the number of cpus like we do for other controls as well.
Reported-by: David Miller <davem@davemloft.net> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> --- kernel/sched.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)
Index: linux-2.6/kernel/sched.c =================================================================== --- linux-2.6.orig/kernel/sched.c +++ linux-2.6/kernel/sched.c @@ -809,9 +809,9 @@ const_debug unsigned int sysctl_sched_nr /* * ratelimit for updating the group shares. - * default: 0.5ms + * default: 0.25ms */ -const_debug unsigned int sysctl_sched_shares_ratelimit = 500000; +const_debug unsigned int sysctl_sched_shares_ratelimit = 250000; /* * period over which we measure -rt task cpu usage in us. @@ -5732,6 +5732,8 @@ static inline void sched_init_granularit sysctl_sched_latency = limit; sysctl_sched_wakeup_granularity *= factor; + + sysctl_sched_shares_ratelimit *= factor; } #ifdef CONFIG_SMP
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