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From: Mel Gorman <mel@csn.ul.ie>
To: Minchan Kim <minchan.kim@gmail.com>
Cc: Namhyung Kim <namhyung@gmail.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	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 14:05:43 +0000	[thread overview]
Message-ID: <20110210140543.GJ17873@csn.ul.ie> (raw)
In-Reply-To: <AANLkTimcLgsdEm6XKESc34Z=nsJkZqz8H1jR-ARZo_Gq@mail.gmail.com>

On Thu, Feb 10, 2011 at 10:38:59PM +0900, Minchan Kim wrote:
> On Thu, Feb 10, 2011 at 10:18 PM, Namhyung Kim <namhyung@gmail.com> wrote:
> > 2011-02-10 (???), 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.

Yep. Principally I *think* used netperf running UDP_STREAM for different
buffer sizes and compared oprofile output but I also ran a battery of
benchmarks to check for any other unexpected regression without profiling.

-- 
Mel Gorman
SUSE Labs

WARNING: multiple messages have this Message-ID (diff)
From: Mel Gorman <mel@csn.ul.ie>
To: Minchan Kim <minchan.kim@gmail.com>
Cc: Namhyung Kim <namhyung@gmail.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	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 14:05:43 +0000	[thread overview]
Message-ID: <20110210140543.GJ17873@csn.ul.ie> (raw)
In-Reply-To: <AANLkTimcLgsdEm6XKESc34Z=nsJkZqz8H1jR-ARZo_Gq@mail.gmail.com>

On Thu, Feb 10, 2011 at 10:38:59PM +0900, Minchan Kim wrote:
> On Thu, Feb 10, 2011 at 10:18 PM, Namhyung Kim <namhyung@gmail.com> wrote:
> > 2011-02-10 (???), 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.

Yep. Principally I *think* used netperf running UDP_STREAM for different
buffer sizes and compared oprofile output but I also ran a battery of
benchmarks to check for any other unexpected regression without profiling.

-- 
Mel Gorman
SUSE Labs

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  parent reply	other threads:[~2011-02-10 14:06 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-02-10 11:46 [RFC PATCH] mm: handle simple case in free_pcppages_bulk() Namhyung Kim
2011-02-10 11:46 ` Namhyung Kim
2011-02-10 13:10 ` Minchan Kim
2011-02-10 13:10   ` Minchan Kim
2011-02-10 13:18   ` Namhyung Kim
2011-02-10 13:18     ` Namhyung Kim
2011-02-10 13:38     ` Minchan Kim
2011-02-10 13:38       ` Minchan Kim
2011-02-10 13:53       ` Namhyung Kim
2011-02-10 13:53         ` Namhyung Kim
2011-02-10 14:05       ` Mel Gorman [this message]
2011-02-10 14:05         ` Mel Gorman

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