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From: Minchan Kim <minchan.kim@gmail.com>
To: Namhyung Kim <namhyung@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Mel Gorman <mel@csn.ul.ie>,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [RFC PATCH] mm: handle simple case in free_pcppages_bulk()
Date: Thu, 10 Feb 2011 22:38:59 +0900	[thread overview]
Message-ID: <AANLkTimcLgsdEm6XKESc34Z=nsJkZqz8H1jR-ARZo_Gq@mail.gmail.com> (raw)
In-Reply-To: <1297343929.1449.3.camel@leonhard>

On Thu, Feb 10, 2011 at 10:18 PM, Namhyung Kim <namhyung@gmail.com> wrote:
> 2011-02-10 (목), 22:10 +0900, Minchan Kim:
>> Hello Namhyung,
>>
>
> Hi Minchan,
>
>
>> On Thu, Feb 10, 2011 at 8:46 PM, Namhyung Kim <namhyung@gmail.com> wrote:
>> > Now I'm seeing that there are some cases to free all pages in a
>> > pcp lists. In that case, just frees all pages in the lists instead
>> > of being bothered with round-robin lists traversal.
>>
>> I though about that but I didn't send the patch.
>> That's because many cases which calls free_pcppages_bulk(,
>> pcp->count,..) are slow path so it adds comparison overhead on fast
>> path while it loses the effectiveness in slow path.
>>
>
> Hmm.. How about adding unlikely() then? Doesn't it help much here?

Yes. It would help but I am not sure how much it is.
AFAIR, when Mel submit the patch, he tried to prove the effectiveness
with some experiment and profiler.
I think if you want it really, we might need some number.
I am not sure it's worth.




-- 
Kind regards,
Minchan Kim

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  reply	other threads:[~2011-02-10 13:39 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-02-10 11:46 Namhyung Kim
2011-02-10 13:10 ` Minchan Kim
2011-02-10 13:18   ` Namhyung Kim
2011-02-10 13:38     ` Minchan Kim [this message]
2011-02-10 13:53       ` Namhyung Kim
2011-02-10 14:05       ` Mel Gorman

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