From: Attila Kinali <attila@kinali.ch>
To: Robert Hancock <hancockrwd@gmail.com>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: Long lasting MM bug when swap is smaller than RAM
Date: Wed, 1 Jul 2009 10:04:32 +0200 [thread overview]
Message-ID: <20090701100432.2d328e46.attila@kinali.ch> (raw)
In-Reply-To: <4A4ABD8F.40907@gmail.com>
On Tue, 30 Jun 2009 19:36:15 -0600
Robert Hancock <hancockrwd@gmail.com> wrote:
> On 06/30/2009 03:58 AM, Attila Kinali wrote:
> > Moin,
> >
> > There has been a bug back in the 2.4.17 days that is somehow
> > triggered by swap being smaller than RAM, which i thought had
> > been fixed long ago, reappeared on one of the machines i manage.
> >
> > <history>
>
> It's quite unlikely what you are seeing is at all related to that
> problem. The VM subsystem has been hugely changed since then.
That's why i thought this problem was fixed.
> You didn't post what the swap usage history before the upgrade was.
Because i don't have any hard data on this. I checked it by hand
from time to time and we never had more than a few MB of swap used.
> But
> swapping does not only occur if memory is running low. If disk usage is
> high then non-recently used data may be swapped out to make more room
> for disk caching.
Hmm..I didn't know this.. thanks!
> Also, by increasing memory from 2GB to 6GB on a 32-bit kernel, some
> memory pressure may actually be increased since many kernel data
> structures can only be in low memory (the bottom 896MB).
Interesting. But shouldnt memory be "swapped" to highmem first
before going out onto disk?
> The more that
> the system memory is increased the more the pressure on low memory can
> become. Using a 64-bit kernel avoids this problem.
Unfortunately, the CPU we have is still a pure 32bit CPU, so this option
cannot be used.
Attila Kinali
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next prev parent reply other threads:[~2009-07-01 8:04 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-06-30 9:58 Attila Kinali
2009-06-30 17:58 ` Hugh Dickins
2009-07-01 7:55 ` Attila Kinali
2009-07-01 1:36 ` Robert Hancock
2009-07-01 8:04 ` Attila Kinali [this message]
2009-07-01 8:08 ` Attila Kinali
2009-07-01 23:15 ` Zan Lynx
2009-07-01 4:21 ` Wu Fengguang
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