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From: Phillip Lougher <phillip@lougher.demon.co.uk>
To: Bryan Henderson <hbryan@us.ibm.com>
Cc: David Chow <davidchow@shaolinmicro.com>, linux-fsdevel@vger.kernel.org
Subject: Re: fs block size and PAGE_CACHE_SIZE
Date: Wed, 07 May 2003 01:59:12 +0100	[thread overview]
Message-ID: <3EB85A60.6080005@lougher.demon.co.uk> (raw)
In-Reply-To: OFF425B5FA.4C85C6AF-ON87256D1E.00731090-88256D1E.0073F46C@us.ibm.com

Bryan Henderson wrote:

>
>>how could I efficient populate one 16k block to page cache(4 pages) at one
>>
>readpage() op?
>
>Why would you want to?  If someone wants to access those other 3 pages,
>they'll have page faults of their own.
>
In an uncompressed filesystem this is not a problem because the 
additional page faults (read_page), will read the pages out of the block 
cache.   However, for a compressed filesystem,   the 16K block would 
have to be (re-)decompressed evey time, because the block is compressed 
in the block cache.  It is much more efficient to push the extra 
decompressed pages into the page cache.

Regards

Phillip Lougher




  reply	other threads:[~2003-05-07  0:45 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2003-05-06 17:42 fs block size and PAGE_CACHE_SIZE David Chow
2003-05-06 19:34 ` Szakacsits Szabolcs
2003-05-06 21:08 ` Bryan Henderson
2003-05-07  0:59   ` Phillip Lougher [this message]
2003-05-12  1:59   ` David Chow
2003-05-06 21:34 ` Trond Myklebust
     [not found]   ` <3EBE85E8.50906@shaolinmicro.com>
2003-05-12  0:31     ` Trond Myklebust
2003-05-12  2:07       ` David Chow
2003-05-12 10:32         ` Anton Altaparmakov
2003-05-12 11:33         ` Phillip Lougher
2003-05-12 17:46           ` David Chow
2003-05-07  0:48 ` Phillip Lougher
2003-05-11 17:12   ` David Chow

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