From: Nick Piggin <nickpiggin@yahoo.com.au>
To: Hans Reiser <reiser@namesys.com>
Cc: Ingo Oeser <ioe-lkml@rameria.de>,
linux-kernel@vger.kernel.org, Andrew Morton <akpm@osdl.org>,
Marr <marr@flex.com>,
reiserfs-dev@namesys.com
Subject: Re: Drastic Slowdown of 'fseek()' Calls From 2.4 to 2.6 -- VMM Change?
Date: Tue, 28 Feb 2006 11:34:11 +1100 [thread overview]
Message-ID: <44039A83.4050604@yahoo.com.au> (raw)
In-Reply-To: <44036670.7060204@namesys.com>
Hans Reiser wrote:
>Sounds like the real problem is that glibc is doing filesystem
>optimizations without making them conditional on the filesystem type.
>
I'm not sure that it should even be conditional on the filesystem type...
To me it seems silly to even bother doing it, although I guess there
is another level of buffering involved which might mean it makes more
sense.
>Does anyone know the email address of the glibc guy so we can ask him
>not to do that?
>
>
Ulrich Drepper I guess. But don't tell him I sent you ;)
>My entry for the ugliest thought of the day: I wonder if the kernel can
>test the glibc version and.....
>
>Hans
>
>Nick Piggin wrote:
>
>
>>Actually glibc tries to turn this pre-read off if the seek is to a page
>>aligned offset, presumably to handle this case. However a big write
>>would only have to RMW the first and last partial pages, so pre-reading
>>128KB in this case is wrong.
>>
>>And I would also say a 4K read is wrong as well, because a big read will
>>be less efficient due to the extra syscall and small IO.
>>
>>
--
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next prev parent reply other threads:[~2006-02-28 0:34 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-02-24 20:22 Drastic Slowdown of 'fseek()' Calls From 2.4 to 2.6 -- VMM Change? Marr
2006-02-25 5:16 ` Andrew Morton
2006-02-26 13:07 ` Ingo Oeser
2006-02-26 13:50 ` Nick Piggin
2006-02-26 14:11 ` Arjan van de Ven
2006-02-27 20:52 ` Hans Reiser
2006-02-28 0:34 ` Nick Piggin [this message]
2006-02-28 18:42 ` Hans Reiser
2006-02-28 18:51 ` Hans Reiser
2006-02-27 20:24 ` Marr
2006-02-27 21:53 ` Hans Reiser
2006-02-28 0:03 ` Bill Davidsen
2006-02-28 18:38 ` Hans Reiser
2006-03-05 23:02 ` Readahead value 128K? (was Re: Drastic Slowdown of 'fseek()' Calls From 2.4 to 2.6 -- VMM Change?) Linda Walsh
2006-03-07 19:53 ` Marr
2006-03-07 21:15 ` Linda Walsh
2006-03-12 21:53 ` Marr
2006-03-12 22:15 ` Mark Lord
2006-03-13 4:36 ` Marr
2006-03-13 14:41 ` Mark Lord
2006-03-13 18:15 ` Hans Reiser
2006-03-13 20:00 ` Marr
[not found] <5JRJO-6Al-7@gated-at.bofh.it>
2006-02-24 23:31 ` Drastic Slowdown of 'fseek()' Calls From 2.4 to 2.6 -- VMM Change? Robert Hancock
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