Date: Fri, 24 Feb 2006 17:31:20 -0600
From: Robert Hancock <hancockr@shaw.ca>
Subject: Re: Drastic Slowdown of 'fseek()' Calls From 2.4 to 2.6 -- VMM Change?
In-reply-to: <5JRJO-6Al-7@gated-at.bofh.it>
To: Marr <marr@flex.com>, linux-kernel <linux-kernel@vger.kernel.org>
Message-id: <43FF9748.9010603@shaw.ca>
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Marr wrote:
> Clearly, the 2.4.31 results are speedy because the whole 4MB file has been 
> cached.

I don't think this is clear at all. The entire file should always be 
cached, not doing this would be insane.

> What I cannot figure out is this: what has changed in 2.6.x kernels to cause 
> the performance to degrade so drastically?!?

fseek() is a C library call, not a system call itself - there may be 
something that glibc is doing differently. Are you using the same glibc 
version with both kernels?

Just from this program it could be something else entirely that explains 
the difference in speed, like the random number generator..

-- 
Robert Hancock      Saskatoon, SK, Canada
To email, remove "nospam" from hancockr@nospamshaw.ca
Home Page: http://www.roberthancock.com/

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