From: Ian Campbell <ian.campbell@citrix.com>
To: Jan Beulich <JBeulich@suse.com>, David Vrabel <david.vrabel@citrix.com>
Cc: julien.grall@citrix.com, andrew.cooper3@citrix.com,
stefano.stabellini@eu.citrix.com, wei.liu2@citrix.com,
xen-devel@lists.xen.org
Subject: Re: [PATCH v2] arm: reduce power use by contented spin locks with WFE/SEV
Date: Tue, 15 Sep 2015 12:17:07 +0100 [thread overview]
Message-ID: <1442315827.3549.380.camel@citrix.com> (raw)
In-Reply-To: <55CA2BDE0200007800099AE6@prv-mh.provo.novell.com>
On Tue, 2015-08-11 at 09:07 -0600, Jan Beulich wrote:
> > > > On 03.08.15 at 13:29, <ian.campbell@citrix.com> wrote:
> > From: David Vrabel <david.vrabel@citrix.com>
> >
> > Instead of cpu_relax() while spinning and observing the ticket head,
> > introduce arch_lock_relax() which executes a WFE instruction. After
> > the ticket head is changed call arch_lock_signal() to execute an SEV
> > instruction (with the required DSB first) to wake any spinners.
> >
> > This should improve power consumption when locks are contented and
> > spinning.
>
> So why not use MONITOR/MWAIT on x86 for the same purpose?
I'll leave this for an x86 person to decide/implement.
Ian.
next prev parent reply other threads:[~2015-09-15 11:17 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-08-03 11:29 [PATCH v2] arm: reduce power use by contented spin locks with WFE/SEV Ian Campbell
2015-08-03 11:51 ` Stefano Stabellini
2015-08-03 11:58 ` Ian Campbell
2015-08-03 12:00 ` Andrew Cooper
2015-08-11 15:07 ` Jan Beulich
2015-09-15 11:17 ` Ian Campbell [this message]
2015-09-15 10:28 ` Ian Campbell
2015-09-15 10:39 ` Stefano Stabellini
2015-09-15 11:17 ` Ian Campbell
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