linux-kernel - Re: How to optimize system time for such case?

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Message-ID: <6278d2220611020110m34d09673yee73edd6c0c86ff@mail.gmail.com>
Date:	Thu, 2 Nov 2006 09:10:11 +0000
From:	"Daniel J Blueman" <daniel.blueman@...il.com>
To:	zhfeng.osprey@...il.com
Cc:	"Linux Kernel" <linux-kernel@...r.kernel.org>
Subject: Re: How to optimize system time for such case?

FENG ZHOU wrote:
> Hello, all
> I am optimizing a compiler and I believe there is a bug in such
> compile. Currently, I have a test case, which is a scientific
> application, has a lot of system time. This is weird, because this
> case does not have many system calls. Meanwhile, compiled at another
> option, I found all the "system time" are gone! So, I assume there is
> some problem in the first one (though both binary produce correct
> result). I used some performance tuning tool and found the hottest
> address for CPU privilege level change event is: 0xa000000100001a70.
> This address is not in code or data segment. Now, I am kinda stuck
> here. My question is: how to find what this address is? Or find out
> what is the cause of the "system time"? Thanks in advance.
>
> PS: the platform is Itanium 2.
> -Feng

First question is what kernel, second is how much memory?

I recently had this experience (high system time) with some vendor
kernels with a system with 16GB of memory and 4-8GB processes. The VM
was trying to reclaim pages like crazy, but failing.
-- 
Daniel J Blueman
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