From: Avi Kivity <avi@redhat.com>
To: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: ben@iagu.net, Eric Dumazet <eric.dumazet@gmail.com>,
Thomas Gleixner <tglx@linutronix.de>,
KVM list <kvm@vger.kernel.org>,
linux-kernel <linux-kernel@vger.kernel.org>,
John Stultz <johnstul@us.ibm.com>,
Richard Cochran <richard.cochran@omicron.at>,
Mike Galbraith <efault@gmx.de>
Subject: Re: [PATCH] posix-timers: RCU conversion
Date: Tue, 05 Apr 2011 11:56:13 +0300 [thread overview]
Message-ID: <4D9AD92D.401@redhat.com> (raw)
In-Reply-To: <1301993300.2225.26.camel@twins>
On 04/05/2011 11:48 AM, Peter Zijlstra wrote:
> What I think is happening is that all your 'idle' qemu thingies keep
> waking up frequently and because you've got like twice the number of
> qemu instances as you've got cpus there's a fair chance you'll have a
> cpu with a pending task while another one goes idle.
Those qemus have two threads each (one vcpu thread, one io thread).
> (Why does qemu keep waking if its idle? broken NOHZ?)
Could be waking up due to guest wakeups, or qemu internal wakeups
(display refresh) or due to guest timer sources which are masked away in
the guest (if that's the case we should optimize it away).
--
error compiling committee.c: too many arguments to function
WARNING: multiple messages have this Message-ID (diff)
From: Avi Kivity <avi@redhat.com>
To: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: ben@iagu.net, Eric Dumazet <eric.dumazet@gmail.com>,
Thomas Gleixner <tglx@linutronix.de>,
KVM list <kvm@vger.kernel.org>,
linux-kernel <linux-kernel@vger.kernel.org>,
John Stultz <johnstul@us.ibm.com>,
Richard Cochran <richard.cochran@omicron.at>,
Mike Galbraith <efault@gmx.de>
Subject: Re: [PATCH] posix-timers: RCU conversion
Date: Tue, 05 Apr 2011 11:56:13 +0300 [thread overview]
Message-ID: <4D9AD92D.401@redhat.com> (raw)
In-Reply-To: <1301993300.2225.26.camel@twins>
On 04/05/2011 11:48 AM, Peter Zijlstra wrote:
> What I think is happening is that all your 'idle' qemu thingies keep
> waking up frequently and because you've got like twice the number of
> qemu instances as you've got cpus there's a fair chance you'll have a
> cpu with a pending task while another one goes idle.
Those qemus have two threads each (one vcpu thread, one io thread).
> (Why does qemu keep waking if its idle? broken NOHZ?)
Could be waking up due to guest wakeups, or qemu internal wakeups
(display refresh) or due to guest timer sources which are masked away in
the guest (if that's the case we should optimize it away).
--
error compiling committee.c: too many arguments to function
next prev parent reply other threads:[~2011-04-05 8:56 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-03-18 12:02 KVM lock contention on 48 core AMD machine Ben Nagy
2011-03-18 12:30 ` Joerg Roedel
2011-03-19 4:45 ` Ben Nagy
2011-03-21 9:50 ` Avi Kivity
2011-03-21 11:43 ` Ben Nagy
2011-03-21 13:41 ` Ben Nagy
2011-03-21 13:53 ` Avi Kivity
[not found] ` <AANLkTikWQS281kTtJ32-qo5U+w_BAak7qUwVhUQgOxxv@mail.gmail.com>
2011-03-21 15:50 ` Avi Kivity
2011-03-21 16:16 ` Ben Nagy
2011-03-21 16:33 ` Avi Kivity
2011-03-21 16:54 ` Eric Dumazet
2011-03-21 17:02 ` Avi Kivity
2011-03-21 17:12 ` Eric Dumazet
2011-03-21 18:12 ` Ben Nagy
2011-03-21 22:27 ` [RFC] posix-timers: RCU conversion Eric Dumazet
2011-03-22 7:09 ` [PATCH] " Eric Dumazet
2011-03-22 8:59 ` Ben Nagy
2011-03-22 10:35 ` Avi Kivity
2011-03-22 10:35 ` Avi Kivity
2011-04-04 3:30 ` Ben Nagy
2011-04-04 7:18 ` Avi Kivity
2011-04-04 7:18 ` Avi Kivity
2011-04-05 7:49 ` Peter Zijlstra
2011-04-05 8:16 ` Avi Kivity
2011-04-05 8:16 ` Avi Kivity
2011-04-05 8:48 ` Peter Zijlstra
2011-04-05 8:56 ` Avi Kivity [this message]
2011-04-05 8:56 ` Avi Kivity
2011-04-05 9:03 ` Peter Zijlstra
2011-04-05 9:08 ` Avi Kivity
2011-04-05 9:08 ` Avi Kivity
2011-04-05 9:50 ` Ben Nagy
2011-04-05 8:56 ` Mike Galbraith
2011-04-03 16:54 ` Eric Dumazet
2011-04-04 18:08 ` john stultz
2011-04-04 19:47 ` Eric Dumazet
2011-04-05 14:48 ` Oleg Nesterov
2011-04-05 15:18 ` [PATCH v2] " Eric Dumazet
2011-04-05 15:43 ` Oleg Nesterov
2011-05-16 15:10 ` Avi Kivity
2011-05-16 15:30 ` Eric Dumazet
2011-04-08 18:28 ` [PATCH] " Paul E. McKenney
2011-03-21 18:14 ` KVM lock contention on 48 core AMD machine Avi Kivity
2011-03-21 18:48 ` Michael Tokarev
2011-03-21 18:53 ` Avi Kivity
2011-03-18 12:44 ` Stefan Hajnoczi
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