From: Jeremy Fitzhardinge <jeremy@goop.org>
To: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Len Brown <lenb@kernel.org>,
venki@google.com, ak@linux.intel.com, suresh.b.siddha@intel.com,
sfr@canb.auug.org.au, peterz@infradead.org,
benh@kernel.crashing.org, linux-kernel@vger.kernel.org,
xen-devel@lists.xensource.com, arjan@linux.intel.com,
Trinabh Gupta <trinabh@linux.vnet.ibm.com>
Subject: Re: [Xen-devel] Re: [RFC PATCH V4 4/5] cpuidle: driver for xen
Date: Fri, 25 Mar 2011 14:38:58 +0000 [thread overview]
Message-ID: <4D8CA902.7090907@goop.org> (raw)
In-Reply-To: <20110324120522.GB29294@dumpdata.com>
On 03/24/2011 12:05 PM, Konrad Rzeszutek Wilk wrote:
> On Thu, Mar 24, 2011 at 03:18:14AM -0400, Len Brown wrote:
>> Is a CONFIG_XEN kernel supposed to use just HLT in idle?
> For right now..
For always, I should think.
>> xen_arch_setup() does this:
>>
>> pm_idle = default_idle;
>> boot_option_idle_override = IDLE_HALT;
>>
>> which has that effect. I guess this makes sense b/c the
>> CONFIG_XEN kernel is Dom0 and the real C-sates are done
>> by the hypervisor?
> Correct. There are some patches that make the C-states
> be visible in the Linux kernel, but that hasn't been ported
> over yet.
All we need is for the idle CPU to block in the hypervisor; a plain
"hlt" is always going to be sufficient (which is overridden as a pvop
into a sched_idle hypercall).
Xen will choose an appropriate power state for the physical cpus
depending on the overall busyness of the system (which any individual
virtual machine can't determine).
J
next prev parent reply other threads:[~2011-03-25 14:39 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-03-22 12:32 [RFC PATCH V4 0/5] cpuidle: Cleanup pm_idle and include driver/cpuidle.c in-kernel Trinabh Gupta
2011-03-22 12:32 ` [RFC PATCH V4 1/5] cpuidle: Remove pm_idle pointer for x86 Trinabh Gupta
2011-03-23 1:00 ` Stephen Rothwell
2011-03-23 10:10 ` Trinabh Gupta
2011-03-22 12:32 ` [RFC PATCH V4 2/5] cpuidle: list based cpuidle driver registration and selection Trinabh Gupta
2011-03-23 2:59 ` Len Brown
2011-03-23 9:22 ` Trinabh Gupta
2011-03-23 20:51 ` Len Brown
2011-03-24 4:41 ` Len Brown
2011-03-24 14:13 ` Trinabh Gupta
2011-03-24 16:52 ` Vaidyanathan Srinivasan
2011-03-25 7:13 ` Len Brown
2011-03-25 7:05 ` Len Brown
2011-03-25 15:35 ` [Xen-devel] " Konrad Rzeszutek Wilk
2011-03-31 2:25 ` Len Brown
2011-03-22 12:33 ` [RFC PATCH V4 3/5] cpuidle: default idle driver for x86 Trinabh Gupta
2011-03-23 3:13 ` Len Brown
2011-03-23 9:31 ` Trinabh Gupta
2011-03-24 16:32 ` Vaidyanathan Srinivasan
2011-03-22 12:33 ` [RFC PATCH V4 4/5] cpuidle: driver for xen Trinabh Gupta
2011-03-22 14:50 ` Konrad Rzeszutek Wilk
2011-03-23 9:57 ` Trinabh Gupta
2011-03-24 7:18 ` Len Brown
2011-03-24 12:05 ` Konrad Rzeszutek Wilk
2011-03-25 7:19 ` Len Brown
2011-03-25 14:43 ` [Xen-devel] " Jeremy Fitzhardinge
2011-03-25 14:38 ` Jeremy Fitzhardinge [this message]
2011-03-31 2:02 ` Len Brown
2011-03-31 21:26 ` Len Brown
2011-03-31 22:36 ` Jeremy Fitzhardinge
2011-04-01 3:03 ` Len Brown
2011-03-22 12:33 ` [RFC PATCH V4 5/5] cpuidle: cpuidle driver for apm Trinabh Gupta
2011-03-23 1:14 ` Stephen Rothwell
2011-03-23 10:25 ` Trinabh Gupta
2011-03-23 20:32 ` Len Brown
2011-03-24 14:28 ` Trinabh Gupta
2011-03-24 16:21 ` Vaidyanathan Srinivasan
2011-03-25 7:24 ` Len Brown
2011-03-25 18:01 ` Vaidyanathan Srinivasan
2011-03-31 2:17 ` cpuidle asymmetry (was Re: [RFC PATCH V4 5/5] cpuidle: cpuidle driver for apm) Len Brown
2011-03-31 13:18 ` Peter Zijlstra
2011-04-01 4:09 ` Len Brown
2011-04-01 8:15 ` Dipankar Sarma
2011-04-01 14:38 ` Arjan van de Ven
2011-04-03 16:18 ` Dipankar Sarma
2011-04-01 14:02 ` Peter Zijlstra
2011-04-04 14:32 ` Dipankar Sarma
2011-04-05 15:01 ` Peter Zijlstra
2011-04-05 15:48 ` Dipankar Sarma
2011-04-01 7:02 ` Trinabh Gupta
2011-03-24 4:27 ` [RFC PATCH V4 5/5] cpuidle: cpuidle driver for apm Len Brown
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