(4/8/13 8:20 AM), Gilad Ben-Yossef wrote:
> On Fri, Apr 5, 2013 at 11:33 PM, Cody P Schafer <c...@linux.vnet.ibm.com>
> wrote:
>> In free_hot_cold_page(), we rely on pcp->batch remaining stable.
>> Updating it without being on the cpu owning the percpu pageset
>> potentially destroys this stability.
>>
>> Change for_each_cpu() to on_each_cpu() to fix.
>
> Are you referring to this? -
>
> 1329 if (pcp->count >= pcp->high) {
> 1330 free_pcppages_bulk(zone, pcp->batch, pcp);
> 1331 pcp->count -= pcp->batch;
> 1332 }
>
> I'm probably missing the obvious but won't it be simpler to do this in
> free_hot_cold_page() -
>
> 1329 if (pcp->count >= pcp->high) {
> 1330 unsigned int batch = ACCESS_ONCE(pcp->batch);
> 1331 free_pcppages_bulk(zone, batch, pcp);
> 1332 pcp->count -= batch;
> 1333 }
>
> Now the batch value used is stable and you don't have to IPI every CPU
> in the system just to change a config knob...
OK, right. Your approach is much better.
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