From: Pierre Beck <mail@pierre-beck.de>
To: linux-kernel@vger.kernel.org
Subject: 3.6-rc7 32-bit PAE miscalculates dirty page limits
Date: Sun, 30 Sep 2012 11:38:45 +0200 [thread overview]
Message-ID: <5068130A.4050602@pierre-beck.de> (raw)
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?
Greetings,
Pierre Beck
next reply other threads:[~2012-09-30 9:38 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-09-30 9:38 Pierre Beck [this message]
2012-09-30 18:52 ` 3.6-rc7 32-bit PAE miscalculates dirty page limits H. Peter Anvin
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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