Re: [PATCH] sched: cpuacct: Use bigger percpu counter batch valuesfor stats counters

From: Balbir Singh
Date: Thu Jan 21 2010 - 10:25:52 EST

On Monday 18 January 2010 03:25 PM, Anton Blanchard wrote:
> Hi Martin,
>> For s390 the jiffies_to_cputime is a compile time constant. No need to
>> initialize it at runtime, no?
> Indeed it is, I didn't look closely enough. Same with ia64 so no work to
> do on either arch :)
>> The patch itself trades some accuracy (larger cpu accounting value that
>> are stored per-cpu) against runtime overhead (spinlock to transfer the
>> value to the global variable in __percpu_counter_add). Did you
>> calculate how big the loss in accuracy is?
> The idea is we are already batching percpu_counter_batch jiffies, so
> with CONFIG_VIRT_CPU_ACCOUNTING we batch the equivalent amount in
> cputime.

Hi, Peter, Ingo

Could we please pick up the patch for -tip?

Three Cheers,
Balbir Singh
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