linux-kernel - Re: [RFC PATCH 0/4] Gang scheduling in CFS

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Message-ID: <4EF1B85F.7060105@redhat.com>
Date:	Wed, 21 Dec 2011 12:43:43 +0200
From:	Avi Kivity <avi@...hat.com>
To:	Nikunj A Dadhania <nikunj@...ux.vnet.ibm.com>
CC:	Ingo Molnar <mingo@...e.hu>, peterz@...radead.org,
	linux-kernel@...r.kernel.org, vatsa@...ux.vnet.ibm.com,
	bharata@...ux.vnet.ibm.com
Subject: Re: [RFC PATCH 0/4] Gang scheduling in CFS

On 12/21/2011 12:39 PM, Nikunj A Dadhania wrote:
> On Mon, 19 Dec 2011 12:23:26 +0100, Ingo Molnar <mingo@...e.hu> wrote:
> > 
> > * Nikunj A. Dadhania <nikunj@...ux.vnet.ibm.com> wrote:
> > 
> > So could we please approach this from the benchmarked workload 
> > angle first? The highest improvement is in ebizzy:
> > 
> > >     ebizzy 2vm (improved 15 times, i.e. 1520%)
> > 
> > What's behind this huge speedup? Does ebizzy use user-space 
> > spinlocks perhaps? Could we do something on the user-space side 
> > to get a similar speedup?
> > 
> This is from the perf run on the host:
>
> Baseline:
>
> 16.22%         qemu-kvm  [kvm_intel]    [k] free_kvm_area
>  8.27%         qemu-kvm  [kvm]          [k] start_apic_timer
>  7.53%         qemu-kvm  [kvm]          [k] kvm_put_guest_fpu
>
> Gang:
>
> 24.44%         qemu-kvm  [kvm_intel]    [k] free_kvm_area
> 13.42%         qemu-kvm  [kvm]          [k] start_apic_timer 
>  9.91%         qemu-kvm  [kvm]          [k] kvm_put_guest_fpu
>
> Ingo, Avi, I am not getting anything obvious from this. Any ideas?
>

Looks like perf is confused, this sometimes happens if you rebuild the
kernel but only rmmod/insmod kvm.  Try a clean build + boot.

-- 
error compiling committee.c: too many arguments to function

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