Re: [PATCH 2/2 v4]mm: batch activate_page() to reduce lock contention

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On Tue, Mar 15, 2011 at 11:28 AM, Andrew Morton
<akpm@xxxxxxxxxxxxxxxxxxxx> wrote:
> On Tue, 15 Mar 2011 11:12:37 +0900 Minchan Kim <minchan.kim@xxxxxxxxx> wrote:
>
>> >> I can't understand why we should hanlde activate_page_pvecs specially.
>> >> Please, enlighten me.
>> > Not it's special. akpm asked me to do it this time. Reducing little
>> > memory is still worthy anyway, so that's it. We can do it for other
>> > pvecs too, in separate patch.
>>
>> Understandable but I don't like code separation by CONFIG_SMP for just
>> little bit enhance of memory usage. In future, whenever we use percpu,
>> do we have to implement each functions for both SMP and non-SMP?
>> Is it desirable?
>> Andrew, Is it really valuable?
>
> It's a little saving of text footprint. ÂIt's also probably faster this way -
> putting all the pages into a pagevec then later processing them won't
> be very L1 cache friendly.
>
>

I am not sure how much effective it is in UP. But if L1 cache friendly
is important concern, we should not use per-cpu about hot operation.
I think more important thing in embedded (normal UP), it is a lock latency.
I don't want to hold/release the lock per page.


-- 
Kind regards,
Minchan Kim

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