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Date: Sun, 20 Jan 2002 13:13:46 -0200 (BRST)
From: Rik van Riel <riel@conectiva.com.br>
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To: Hans Reiser <reiser@namesys.com>
Cc: Shawn <spstarr@sh0n.net>, <linux-kernel@vger.kernel.org>,
        Josh MacDonald <jmacd@CS.Berkeley.EDU>
Subject: Re: Possible Idea with filesystem buffering.
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On Sun, 20 Jan 2002, Hans Reiser wrote:

> Write clustering is one thing it achieves.
>
> Flushing everything involved in a transaction ... is another thing.

Agreed on these points, but you really HAVE TO work towards
flushing the page ->writepage() gets called for.

Think about your typical PC, with memory in ZONE_DMA,
ZONE_NORMAL and ZONE_HIGHMEM. If we are short on DMA pages
we will end up calling ->writepage() on a DMA page.

If the filesystem ends up writing completely unrelated pages
and marking the DMA page in question referenced the VM will
go in a loop until the filesystem finally gets around to
making a page in the (small) DMA zone freeable ...

regards,

Rik
-- 
"Linux holds advantages over the single-vendor commercial OS"
    -- Microsoft's "Competing with Linux" document

http://www.surriel.com/		http://distro.conectiva.com/

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