From: Len Brown <lenb@kernel.org>
To: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>
Cc: Trinabh Gupta <trinabh@linux.vnet.ibm.com>,
arjan@linux.intel.com, peterz@infradead.org,
suresh.b.siddha@intel.com, benh@kernel.crashing.org,
venki@google.com, ak@linux.intel.com,
linux-kernel@vger.kernel.org, sfr@canb.auug.org.au,
xen-devel@lists.xensource.com
Subject: Re: [RFC PATCH V4 2/5] cpuidle: list based cpuidle driver registration and selection
Date: Fri, 25 Mar 2011 03:13:04 -0400 (EDT) [thread overview]
Message-ID: <alpine.LFD.2.02.1103250307330.32565@x980> (raw)
In-Reply-To: <20110324165200.GC16408@dirshya.in.ibm.com>
> > So what do you suggest can be removed?
>
> Can we use safe_halt() until intel_idle/acpi_idle take over? But what
> if they do not take over? If safe_halt() is not very bad compared to
> the variants like mwait_idle and c1e_idle, then we can remove the old
> code and no need to move them to default driver.
One reason I'd like a default cpuidle driver is that today
there is a race. cpuidle registers, but until its driver
registers it will use polling. go ahead and look:
grep . /sys/devices/system/cpu/cpu*/cpuidle/state0/usage
that should be 0, but it isn't...
> > >Are we suggesting that x86 must always build with cpuidle?
> > >I'm sure that somebody someplace will object to that.
> >
> > Arjan argued that since almost everyone today runs cpuidle
> > it may be best to include it in the kernel
> > (https://lkml.org/lkml/2010/10/20/243). But yes, we agreed
> > that we would have to make cpuidle lighter incrementally.
> > Making ladder governor optional could be one way for example.
> > >
> > >OTOH, if cpuidle is included, I'd like to see the
> > >non-cpuidle code excluded, since nobody will run it...
>
> The non-cpuidle code will be the select_idle_routine() and related
> function that cam move to default_driver that register to cpuidle.
> We can load on-demand as module if better routines fail to register.
> Maybe we don't need this at all as discussed in the above point?
Right, though I don't share your fascination with modules.
cheers,
Len Brown, Intel Open Source Technology Center
next prev parent reply other threads:[~2011-03-25 7:13 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 [this message]
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
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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