Re: Unending loop in __alloc_pages_slowpath following OOM-kill; rfc:patch.

From: KOSAKI Motohiro
Date: Tue May 24 2011 - 05:06:15 EST


>>> Why?
>>
>> Otherwise, we don't have good PCP dropping trigger. Big machine might have
>> big pcp cache.
>>
>
> Big machines also have a large cost for sending IPIs.

Yes. But it's only matter if IPIs are frequently happen.
But, drain_all_pages() is NOT only IPI source. some vmscan function (e.g.
try_to_umap) makes a lot of IPIs.

Then, it's _relatively_ not costly. I have a question. Do you compare which
operation and drain_all_pages()? IOW, your "costly" mean which scenario suspect?




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