From: David Ahern <daahern@cisco.com>
To: Avi Kivity <avi@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>,
Marcelo Tosatti <mtosatti@redhat.com>,
kvm@vger.kernel.org, Ingo Molnar <mingo@elte.hu>,
Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Subject: Re: [PATCH v2 00/11] KVM in-guest performance monitoring
Date: Thu, 16 Jun 2011 11:16:09 -0600 [thread overview]
Message-ID: <4DFA3A59.20007@cisco.com> (raw)
In-Reply-To: <4DFA2FC8.4080704@redhat.com>
On 06/16/2011 10:31 AM, Avi Kivity wrote:
> On 06/16/2011 07:04 PM, David Ahern wrote:
>>
>> On 06/16/2011 09:59 AM, Avi Kivity wrote:
>> > On 06/16/2011 06:34 PM, David Ahern wrote:
>> >> >
>> >> > main ()
>> >> > {
>> >> > int i;
>> >> >
>> >> > fork();
>> >> > fork();
>> >
>> > What happens without the two forks?
>> >
>>
>> you have a 1-billion instruction benchmark since there is only 1 process.
>>
>
> I mean in terms of the overhead. Is the overhead due to context
> switches being made more expensive by the pmu, or is it something else?
I figured you meant something else by the question.
>
> But there were only 337 context switches in your measurement, they
> couldn't possibly be so bad.
> Anyway I'll investigate it.
>
I don't think it's the context switching. See the email on perf-report
and perf-annotate from the host side while running perf-stat in the
guest. Perhaps more vmexits and associated preemption disable/enable
overhead - or the rcu change?
David
next prev parent reply other threads:[~2011-06-16 17:16 UTC|newest]
Thread overview: 57+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-06-13 13:34 [PATCH v2 00/11] KVM in-guest performance monitoring Avi Kivity
2011-06-13 13:34 ` [PATCH v2 01/11] perf: add context field to perf_event Avi Kivity
2011-06-13 13:34 ` [PATCH v2 02/11] x86, perf: add constraints for architectural PMU v1 Avi Kivity
2011-06-13 13:34 ` [PATCH v2 03/11] perf: export perf_event_refresh() to modules Avi Kivity
2011-06-13 13:34 ` [PATCH v2 04/11] KVM: Expose kvm_lapic_local_deliver() Avi Kivity
2011-06-13 13:35 ` [PATCH v2 05/11] KVM: Expose a version 1 architectural PMU to guests Avi Kivity
2011-06-13 18:10 ` David Ahern
2011-06-14 8:33 ` Avi Kivity
2011-06-27 14:10 ` lidong chen
2011-06-27 14:13 ` Avi Kivity
2011-06-28 2:54 ` lidong chen
2011-06-28 8:15 ` Avi Kivity
2011-06-13 13:35 ` [PATCH v2 06/11] KVM: Add generic RDPMC support Avi Kivity
2011-06-13 13:35 ` [PATCH v2 07/11] KVM: SVM: Intercept RDPMC Avi Kivity
2011-06-13 13:35 ` [PATCH v2 08/11] KVM: VMX: " Avi Kivity
2011-06-13 16:17 ` David Ahern
2011-06-13 16:29 ` Avi Kivity
2011-06-13 16:59 ` David Ahern
2011-06-13 17:38 ` Ingo Molnar
2011-06-13 18:09 ` David Ahern
2011-06-14 8:34 ` Avi Kivity
2011-06-14 9:27 ` Ingo Molnar
2011-06-13 13:35 ` [PATCH v2 09/11] KVM: Expose the architectural performance monitoring CPUID leaf Avi Kivity
2011-06-13 13:35 ` [PATCH v2 10/11] KVM: x86 emulator: fix RDPMC privilege check Avi Kivity
2011-06-13 13:35 ` [PATCH v2 11/11] KVM: x86 emulator: implement RDPMC (0F 33) Avi Kivity
2011-06-13 19:55 ` [PATCH v2 00/11] KVM in-guest performance monitoring David Ahern
2011-06-14 8:36 ` Avi Kivity
2011-06-14 17:15 ` David Ahern
2011-06-14 17:24 ` Jan Kiszka
2011-06-14 17:33 ` David Ahern
2011-06-14 17:48 ` David Ahern
2011-06-14 18:11 ` David Ahern
2011-06-15 8:57 ` Avi Kivity
2011-06-15 12:40 ` David Ahern
2011-06-15 13:22 ` Avi Kivity
2011-06-15 16:08 ` David Ahern
2011-06-15 16:27 ` Avi Kivity
2011-06-15 16:51 ` David Ahern
2011-06-16 13:53 ` Avi Kivity
2011-06-16 14:08 ` David Ahern
2011-06-16 14:19 ` David Ahern
2011-06-16 14:20 ` Avi Kivity
2011-06-16 14:32 ` David Ahern
2011-06-16 14:36 ` Avi Kivity
2011-06-16 15:04 ` David Ahern
2011-06-16 15:08 ` Peter Zijlstra
2011-06-16 15:18 ` David Ahern
2011-06-16 15:19 ` David Ahern
2011-06-16 15:27 ` Peter Zijlstra
2011-06-16 15:34 ` David Ahern
2011-06-16 15:59 ` Avi Kivity
2011-06-16 16:04 ` David Ahern
2011-06-16 16:31 ` Avi Kivity
2011-06-16 17:16 ` David Ahern [this message]
2011-06-29 7:52 ` Avi Kivity
2011-06-29 8:38 ` Peter Zijlstra
2011-06-29 9:26 ` Avi Kivity
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