From: Suleiman Souhlal <ssouhlal@FreeBSD.org>
To: akpm@osdl.org
Cc: linux-kernel@vger.kernel.org, balbir@in.ibm.com,
csturtiv@sgi.com, daw@sgi.com, guillaume.thouvenin@bull.net,
jlan@sgi.com, nagar@watson.ibm.com, tee@sgi.com
Subject: Re: [patch 03/13] io-accounting: write accounting
Date: Wed, 13 Dec 2006 00:45:50 -0800 [thread overview]
Message-ID: <457FBDBE.10102@FreeBSD.org> (raw)
In-Reply-To: <200612081152.kB8BqQvb019756@shell0.pdx.osdl.net>
akpm@osdl.org wrote:
> From: Andrew Morton <akpm@osdl.org>
>
> Accounting writes is fairly simple: whenever a process flips a page from clean
> to dirty, we accuse it of having caused a write to underlying storage of
> PAGE_CACHE_SIZE bytes.
On architectures where dirtying a page doesn't cause a page fault (like i386), couldn't you end up billing the wrong process (in fact, I think that even on other archituctures set_page_dirty() doesn't get called immediately in the page fault handler)?
AFAICS, set_page_dirty() is mostly called when trying to unmap a page when trying to shrink LRU lists, and there is no guarantee that this happens under the process that dirtied it (in fact, the set_page_dirty() is often done by kswapd).
-- Suleiman
next prev parent reply other threads:[~2006-12-13 9:17 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-12-08 11:52 [patch 03/13] io-accounting: write accounting akpm
2006-12-13 8:45 ` Suleiman Souhlal [this message]
2006-12-13 8:59 ` Andrew Morton
2006-12-13 10:04 ` Peter Zijlstra
2006-12-13 10:35 ` Suleiman Souhlal
2006-12-13 11:02 ` Suleiman Souhlal
2006-12-13 19:07 ` Andrew Morton
2006-12-13 22:00 ` Andrew Morton
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