From: "H. Peter Anvin" <hpa@zytor.com>
To: Pierre Beck <mail@pierre-beck.de>
Cc: linux-kernel@vger.kernel.org
Subject: Re: 3.6-rc7 32-bit PAE miscalculates dirty page limits
Date: Sun, 30 Sep 2012 11:52:05 -0700 [thread overview]
Message-ID: <506894D5.5060101@zytor.com> (raw)
In-Reply-To: <5068130A.4050602@pierre-beck.de>
On 09/30/2012 02:38 AM, Pierre Beck wrote:
> Hi,
>
> there seems to be a bug in either ext4 or VM code triggered with 16 GB
> memory when compiled with 32-bit and PAE. dirty_background_ratio
> defaults to 10, dirty_ratio to 20. But in effect, dirty pages are
> strongly limited (zero or negative?). I observed extreme I/O wait states
> and slow disk access. A quick cure was to set dirty_bytes and
> dirty_background_bytes to sane values, overriding the ratios. An
> educated guess: the result of dirty_ratio calculation is stored as an
> unsigned 32-bit integer and overflows?
>
Seriously, why are you running a 32-bit kernel on memory sizes this
large? Yes, in theory it should work up to 64 GB but claims are that
the kernel doesn't even boot if you try...
-hpa
--
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel. I don't speak on their behalf.
next prev parent reply other threads:[~2012-09-30 18:52 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-09-30 9:38 3.6-rc7 32-bit PAE miscalculates dirty page limits Pierre Beck
2012-09-30 18:52 ` H. Peter Anvin [this message]
2012-10-01 21:10 ` Pierre Beck
2012-10-01 21:52 ` Borislav Petkov
2012-10-01 21:53 ` H. Peter Anvin
2012-10-01 21:59 ` Borislav Petkov
2012-10-01 22:00 ` H. Peter Anvin
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