From: Len Brown <lenb@kernel.org>
To: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Trinabh Gupta <trinabh@linux.vnet.ibm.com>,
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
Subject: Re: [Xen-devel] Re: [RFC PATCH V4 2/5] cpuidle: list based cpuidle driver registration and selection
Date: Wed, 30 Mar 2011 22:25:36 -0400 (EDT) [thread overview]
Message-ID: <alpine.LFD.2.02.1103302222180.1920@x980> (raw)
In-Reply-To: <20110325153524.GN27651@dumpdata.com>
thanks,
Len Brown, Intel Open Source Technology Center
On Fri, 25 Mar 2011, Konrad Rzeszutek Wilk wrote:
> On Fri, Mar 25, 2011 at 03:05:36AM -0400, Len Brown wrote:
> > > I think there are other problems too, related to saving and restoring
> > > of pm_idle pointer. For example, cpuidle itself saves current value
> > > of pm_idle, flips it and then restores the saved value. There is
> > > no guarantee that the saved function still exists. APM does exact
> > > same thing (though it may not be used these days).
> > >
> > > The problem also is that a number of architectures have copied the
> > > same design based on pm_idle; so its spreading.
> >
> > pm_idle is a primitive design yes, but I think the issue
> > with pm_idle is a theoretical one, at least on x86;
> > as there isn't any other code scribbling on pm_idle
> > in practice. So this is clean-up, rather than bug-fix work...
> >
> > > > It isn't immediately clear to me that all of these options
> > > > need to be preserved.
> > >
> > > So what do you suggest can be removed?
> >
> > I sent a series of small patches yesterday to get the ball rolling...
> > https://lkml.org/lkml/2011/3/24/54
> >
> > I think the xen thing can go away.
>
> The xen thing being the setting of cpuidle to halt or the proposed
> patch?
I don't think Xen needs a cpuidle driver.
Xen just needs to tell the kernel to call HALT,
and I think we'll keep that around for the non-cpuidle case,
and for the idle periods before cpuidle initializes.
cheers,
Len Brown, Intel Open Source Technology Center
next prev parent reply other threads:[~2011-03-31 2:26 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 [this message]
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
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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