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DateMon, 18 Jan 2010 16:30:53 +0530
FromBalbir Singh <>
SubjectRe: [PATCH] sched: cpuacct: Use bigger percpu counter batch values for stats counters
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.
>

This patch worked well for me.

Acked-by: Balbir Singh <balbir@linux.vnet.ibm.com>
Tested-by: Balbir Singh <balbir@linux.vnet.ibm.com>

Balbir Singh.


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