Re: [Xen-devel] [PATCH v2] arm: reduce power use by contented spin locks with WFE/SEV

2015-09-15 Thread Ian Campbell
On Tue, 2015-09-15 at 11:39 +0100, Stefano Stabellini wrote: > On Tue, 15 Sep 2015, Ian Campbell wrote: > > On Mon, 2015-08-03 at 12:29 +0100, Ian Campbell wrote: > > > From: David Vrabel > > > > > > Instead of cpu_relax() while spinning and observing the ticket head, > > > introduce arch_lock_re

Re: [Xen-devel] [PATCH v2] arm: reduce power use by contented spin locks with WFE/SEV

2015-09-15 Thread Ian Campbell
On Tue, 2015-08-11 at 09:07 -0600, Jan Beulich wrote: > > > > On 03.08.15 at 13:29, wrote: > > From: David Vrabel > > > > 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 c

Re: [Xen-devel] [PATCH v2] arm: reduce power use by contented spin locks with WFE/SEV

2015-09-15 Thread Stefano Stabellini
On Tue, 15 Sep 2015, Ian Campbell wrote: > On Mon, 2015-08-03 at 12:29 +0100, Ian Campbell wrote: > > From: David Vrabel > > > > 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 cha

Re: [Xen-devel] [PATCH v2] arm: reduce power use by contented spin locks with WFE/SEV

2015-09-15 Thread Ian Campbell
On Mon, 2015-08-03 at 12:29 +0100, Ian Campbell wrote: > From: David Vrabel > > 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 > inst

Re: [Xen-devel] [PATCH v2] arm: reduce power use by contented spin locks with WFE/SEV

2015-08-11 Thread Jan Beulich
>>> On 03.08.15 at 13:29, wrote: > From: David Vrabel > > 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 req

Re: [Xen-devel] [PATCH v2] arm: reduce power use by contented spin locks with WFE/SEV

2015-08-03 Thread Andrew Cooper
On 03/08/15 12:29, Ian Campbell wrote: > From: David Vrabel > > 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

Re: [Xen-devel] [PATCH v2] arm: reduce power use by contented spin locks with WFE/SEV

2015-08-03 Thread Ian Campbell
On Mon, 2015-08-03 at 12:51 +0100, Stefano Stabellini wrote: > On Mon, 3 Aug 2015, Ian Campbell wrote: > > From: David Vrabel > > > > Instead of cpu_relax() while spinning and observing the ticket head, > > introduce arch_lock_relax() which executes a WFE instruction. After > > the ticket head i

Re: [Xen-devel] [PATCH v2] arm: reduce power use by contented spin locks with WFE/SEV

2015-08-03 Thread Stefano Stabellini
On Mon, 3 Aug 2015, Ian Campbell wrote: > From: David Vrabel > > 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 t

[Xen-devel] [PATCH v2] arm: reduce power use by contented spin locks with WFE/SEV

2015-08-03 Thread Ian Campbell
From: David Vrabel 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 s