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Date: Mon, 21 Jan 2002 04:01:27 +0300
From: Hans Reiser <reiser@namesys.com>
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To: Rik van Riel <riel@conectiva.com.br>
CC: Shawn Starr <spstarr@sh0n.net>, linux-kernel@vger.kernel.org
Subject: Re: Possible Idea with filesystem buffering.
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Rik van Riel wrote:

>On Mon, 21 Jan 2002, Hans Reiser wrote:
>
>>Suppose we do what you ask, and always write the page (as well as some
>>other pages) to disk.  This will result in the filesystem cache as a
>>whole receiving more pressure than other caches that only write one
>>page in response to pressure.  This is unbalanced, leads to some
>>caches having shorter average page lifetimes than others, and it is
>>therefor suboptimal.  Yes?
>>
>
>If your ->writepage() writes pages to disk it just means
>that reiserfs will be able to clean its pages faster than
>the other filesystems.
>
the logical extreme of this is that no write caching should be done at 
all, only read caching?

>
>
>This means the VM will not call reiserfs ->writepage() as
>often as for the other filesystems, since more of the
>pages it finds will already be clean and freeable.
>
>I guess the only way to unbalance the caches is by actually
>freeing pages in ->writepage, but I don't see any real reason
>why you'd want to do that...
>
>regards,
>
>Rik
>
It would unbalance the write cache, not the read cache.

Hans

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