From: Andrew Morton <akpm@linux-foundation.org>
To: Pavel Machek <pavel@ucw.cz>
Cc: Mikulas Patocka <mikulas@artax.karlin.mff.cuni.cz>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: swapping when there's a free memory
Date: Mon, 26 Apr 2010 15:33:33 -0700 [thread overview]
Message-ID: <20100426153333.93c03e98.akpm@linux-foundation.org> (raw)
In-Reply-To: <20100425071349.GA1275@ucw.cz>
On Sun, 25 Apr 2010 09:13:49 +0200
Pavel Machek <pavel@ucw.cz> wrote:
> Hi!
>
> > I captured this output of vmstat. The machine was freeing cache and
> > swapping out pages even when there was a plenty of free memory.
> >
> > The machine is sparc64 with 1GB RAM with 2.6.34-rc4. This abnormal
> > swapping happened during running spadfsck --- a fsck program for a custom
> > filesystem that caches most reads in its internal cache --- so it reads
> > buffers and allocates memory at the same time.
> >
> > Note that sparc64 doesn't have any low/high memory zones, so it couldn't
> > be explained by filling one zone and needing to allocate pages in it.
>
> Fragmented memory + high-order allocation?
Yeah, could be. I wonder which slab/slub/slob implementation you're
using, and what page sizes it uses for dentries, inodes, etc. Can you
have a poke in /prob/slabinfo?
> > This abnormal behavior doesn't happen everytime, it happend about twice
> > for many spadfsck attempts.
>
> ...yep, that would be random.
WARNING: multiple messages have this Message-ID (diff)
From: Andrew Morton <akpm@linux-foundation.org>
To: Pavel Machek <pavel@ucw.cz>
Cc: Mikulas Patocka <mikulas@artax.karlin.mff.cuni.cz>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: swapping when there's a free memory
Date: Mon, 26 Apr 2010 15:33:33 -0700 [thread overview]
Message-ID: <20100426153333.93c03e98.akpm@linux-foundation.org> (raw)
In-Reply-To: <20100425071349.GA1275@ucw.cz>
On Sun, 25 Apr 2010 09:13:49 +0200
Pavel Machek <pavel@ucw.cz> wrote:
> Hi!
>
> > I captured this output of vmstat. The machine was freeing cache and
> > swapping out pages even when there was a plenty of free memory.
> >
> > The machine is sparc64 with 1GB RAM with 2.6.34-rc4. This abnormal
> > swapping happened during running spadfsck --- a fsck program for a custom
> > filesystem that caches most reads in its internal cache --- so it reads
> > buffers and allocates memory at the same time.
> >
> > Note that sparc64 doesn't have any low/high memory zones, so it couldn't
> > be explained by filling one zone and needing to allocate pages in it.
>
> Fragmented memory + high-order allocation?
Yeah, could be. I wonder which slab/slub/slob implementation you're
using, and what page sizes it uses for dentries, inodes, etc. Can you
have a poke in /prob/slabinfo?
> > This abnormal behavior doesn't happen everytime, it happend about twice
> > for many spadfsck attempts.
>
> ...yep, that would be random.
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next prev parent reply other threads:[~2010-04-26 22:34 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-04-22 0:55 swapping when there's a free memory Mikulas Patocka
2010-04-25 7:13 ` Pavel Machek
2010-04-26 22:33 ` Andrew Morton [this message]
2010-04-26 22:33 ` Andrew Morton
2010-04-27 1:35 ` KAMEZAWA Hiroyuki
2010-04-27 1:35 ` KAMEZAWA Hiroyuki
2010-04-30 3:52 ` Mikulas Patocka
2010-04-30 3:52 ` Mikulas Patocka
2010-04-26 22:31 ` Andrew Morton
2010-04-26 22:31 ` Andrew Morton
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