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From: Bill Davidsen <davidsen@tmr.com>
To: Hans Reiser <reiser@namesys.com>
Cc: Marr <marr@flex.com>,
	linux-kernel@vger.kernel.org, reiserfs-dev@namesys.com
Subject: Re: Drastic Slowdown of 'fseek()' Calls From 2.4 to 2.6 -- VMM Change?
Date: Mon, 27 Feb 2006 19:03:38 -0500	[thread overview]
Message-ID: <4403935A.3080503@tmr.com> (raw)
In-Reply-To: <440374DF.8080901@namesys.com>

Hans Reiser wrote:
> Andrew Morton wrote:
> 
>> runs like a dog on 2.6's reiserfs.  libc is doing a (probably) 128k read
>> on every fseek.
>>
>> - There may be a libc stdio function which allows you to tune this
>>  behaviour.
>>
>> - libc should probably be a bit more defensive about this anyway -
>>  plainly the filesystem is being silly.
>>  
>>
> I really thank you for isolating the problem, but I don't see how you
> can do other than blame glibc for this.  The recommended IO size is only
> relevant to uncached data, and glibc is using it regardless of whether
> or not it is cached or uncached.   Do I misunderstand something myself here?

I think the issue is not "blame" but what effect this behavior would 
have on things like database loads, where seek-write would be common. 
Good to get this info to users and admins.

-- 
    -bill davidsen (davidsen@tmr.com)
"The secret to procrastination is to put things off until the
  last possible moment - but no longer"  -me


  reply	other threads:[~2006-02-28  0:15 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
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 [this message]
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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