linux-kernel - mm: dirty page problem

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Date:	Tue, 23 Jun 2009 16:17:06 +0800
From:	xue yong <ultraice.kernel@...il.com>
To:	linux-kernel@...r.kernel.org
Subject: mm: dirty page problem

I wrote a test program. It  mmap  a file and do some write, so some
pages become dirty.
and then I do "cat /proc/meminfo", so I get dirty pages that I have
written. this happened in my home
computer with debian, self compiled kernel 2.6.18-5 installed.

but in my company, on the servers (suse kernel 2.6.16.54), after the
test program have written the data, there was no change in
dirty pages column of "cat /proc/meminfo" 's output. after I killed
the test program, the dirty pages changed immediately.

I dont know why such different behavior, can you help me?

becauce we want a program mmap some files, and after the files'
contents were changed, the OS can write out these dirty
data back to disk periodly.

Best regards!

Download attachment "mmaptest.c" of type "application/octet-stream" (1480 bytes)