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Subject: RE: Large increase in context switch rate
Date: Thu, 17 Jul 2008 16:14:00 +0100
Message-ID: <0E902970173AF84089673FA54B7FE78A32906B@lonpexch01.citrite.net>
In-Reply-To: <487F5F15.4050208@goop.org>
Thread-Topic: Large increase in context switch rate
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References: <487E43D9.7080703@goop.org> <1216286250.5232.67.camel@twins> <487F5F15.4050208@goop.org>
From: "Alex Nixon (Intern)" <Alex.Nixon@eu.citrix.com>
To: "Jeremy Fitzhardinge" <jeremy@goop.org>,
       "Peter Zijlstra" <peterz@infradead.org>
Cc: "Ingo Molnar" <mingo@elte.hu>,
       "Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>,
       "Ian Campbell" <Ian.Campbell@eu.citrix.com>
Sender: linux-kernel-owner@vger.kernel.org
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Yeah I've checked - the number of context switches seems to be around
60k regardless of whether CONFIG_PARAVIRT is switched on, and regardless
of whether it's running in domu or native (-j4 on dual core)

-----Original Message-----
From: Jeremy Fitzhardinge [mailto:jeremy@goop.org] 
Sent: 17 July 2008 16:03
To: Peter Zijlstra
Cc: Ingo Molnar; Linux Kernel Mailing List; Alex Nixon (Intern); Ian
Campbell
Subject: Re: Large increase in context switch rate

Peter Zijlstra wrote:
> Is this specific to Xen?, as a native kernel doesn't do more than ~3k
> cs/s with make -j3 on my dual core.
>   

No, it doesn't seem to be.  A CONFIG_PARAVIRT kernel running on bare 
hardware shows the same context switch rate.  Merely turning 
CONFIG_PARAVIRT on should have no effect on context switch rate (though,

Alex, it would be worth double-checking, just to be sure).

    J
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