linux-kernel - Re: miserable performance of 2.6.21 under network load

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Message-ID: <20070724191347.GB359@one.firstfloor.org>
Date:	Tue, 24 Jul 2007 21:13:47 +0200
From:	Andi Kleen <andi@...stfloor.org>
To:	Aaron Porter <atporter@...mate.net>
Cc:	Andi Kleen <andi@...stfloor.org>, linux-kernel@...r.kernel.org
Subject: Re: miserable performance of 2.6.21 under network load

> # opreport -l
> CPU: AMD64 processors, speed 1994.52 MHz (estimated)
> Counted CPU_CLK_UNHALTED events (Cycles outside of halt state) with a unit mask of 0x00 (No unit mask) count 100000
> samples  %        app name                 symbol name
> 914379   48.8404  vmlinux-2.6.21.5         check_poison_obj
> 341920   18.2632  vmlinux-2.6.21.5         poison_obj

You have slab debugging enabled. That makes everything slow.
It costs you ~66% of your CPU time.  Disable it.

-Andi

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