From: Andi Kleen <andi@firstfloor.org>
To: David Woodhouse <dwmw2@infradead.org>
Cc: Andi Kleen <andi@firstfloor.org>,
john cooper <john.cooper@third-harmonic.com>,
Avi Kivity <avi@redhat.com>, Gleb Natapov <gleb@redhat.com>,
linux-kernel@vger.kernel.org, kvm@vger.kernel.org, hpa@zytor.com,
mingo@elte.hu, npiggin@suse.de, tglx@linutronix.de,
mtosatti@redhat.com, john cooper <john.cooper@redhat.com>
Subject: Re: [PATCH] use unfair spinlock when running on hypervisor.
Date: Thu, 3 Jun 2010 17:15:58 +0200 [thread overview]
Message-ID: <20100603151558.GD4166@basil.fritz.box> (raw)
In-Reply-To: <1275563199.2383.1873.camel@macbook.infradead.org>
On Thu, Jun 03, 2010 at 12:06:39PM +0100, David Woodhouse wrote:
> On Tue, 2010-06-01 at 21:36 +0200, Andi Kleen wrote:
> > > Collecting the contention/usage statistics on a per spinlock
> > > basis seems complex. I believe a practical approximation
> > > to this are adaptive mutexes where upon hitting a spin
> > > time threshold, punt and let the scheduler reconcile fairness.
> >
> > That would probably work, except: how do you get the
> > adaptive spinlock into a paravirt op without slowing
> > down a standard kernel?
>
> It only ever comes into play in the case where the spinlock is contended
> anyway -- surely it shouldn't be _that_ much of a performance issue?
The problem is fitting the state into the u32
Also "lightly contended" is not that uncommon.
-Andi
--
ak@linux.intel.com -- Speaking for myself only.
next prev parent reply other threads:[~2010-06-03 15:16 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-06-01 9:35 [PATCH] use unfair spinlock when running on hypervisor Gleb Natapov
2010-06-01 15:53 ` Andi Kleen
2010-06-01 16:24 ` Gleb Natapov
2010-06-01 16:38 ` Andi Kleen
2010-06-01 16:52 ` Avi Kivity
2010-06-01 17:27 ` Andi Kleen
2010-06-02 2:51 ` Avi Kivity
2010-06-02 5:26 ` Srivatsa Vaddagiri
2010-06-02 8:50 ` Andi Kleen
2010-06-02 9:00 ` Avi Kivity
2010-06-03 4:20 ` Srivatsa Vaddagiri
2010-06-03 4:51 ` Eric Dumazet
2010-06-03 5:38 ` Srivatsa Vaddagiri
2010-06-03 8:52 ` Andi Kleen
2010-06-03 9:26 ` Srivatsa Vaddagiri
2010-06-03 10:22 ` Nick Piggin
2010-06-03 10:38 ` Nick Piggin
2010-06-03 12:04 ` Srivatsa Vaddagiri
2010-06-03 12:38 ` Nick Piggin
2010-06-03 12:58 ` Srivatsa Vaddagiri
2010-06-03 13:04 ` Srivatsa Vaddagiri
2010-06-03 13:45 ` Nick Piggin
2010-06-03 14:48 ` Srivatsa Vaddagiri
2010-06-03 15:17 ` Andi Kleen
2010-06-03 15:35 ` Nick Piggin
2010-06-03 17:25 ` Andi Kleen
2010-06-01 17:39 ` Valdis.Kletnieks
2010-06-02 2:46 ` Avi Kivity
2010-06-02 7:39 ` H. Peter Anvin
2010-06-01 17:54 ` john cooper
2010-06-01 19:36 ` Andi Kleen
2010-06-03 11:06 ` David Woodhouse
2010-06-03 15:15 ` Andi Kleen [this message]
2010-06-01 21:39 ` Eric Dumazet
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