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xen-devel
[Xen-devel] Re: cpuidle asymmetry (was Re: [RFC PATCH V4 5/5] cpuidle: c
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To: |
Len Brown <lenb@xxxxxxxxxx> |
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Subject: |
[Xen-devel] Re: cpuidle asymmetry (was Re: [RFC PATCH V4 5/5] cpuidle: cpuidle driver for apm) |
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From: |
Peter Zijlstra <peterz@xxxxxxxxxxxxx> |
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Date: |
Fri, 01 Apr 2011 16:02:36 +0200 |
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Cc: |
Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx>, ak@xxxxxxxxxxxxxxx, suresh.b.siddha@xxxxxxxxx, venki@xxxxxxxxxx, benh@xxxxxxxxxxxxxxxxxxx, linux-kernel@xxxxxxxxxxxxxxx, xen-devel@xxxxxxxxxxxxxxxxxxx, Vaidyanathan Srinivasan <svaidy@xxxxxxxxxxxxxxxxxx>, arjan@xxxxxxxxxxxxxxx, Trinabh Gupta <trinabh@xxxxxxxxxxxxxxxxxx> |
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Delivery-date: |
Fri, 01 Apr 2011 07:04:58 -0700 |
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www-data@xxxxxxxxxxxxxxxxxxx |
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<alpine.LFD.2.02.1104010006210.2797@x980> |
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<20110322123208.28725.30945.stgit@xxxxxxxxxxxxxxxxxxx> <20110322123336.28725.29810.stgit@xxxxxxxxxxxxxxxxxxx> <20110323121458.ec7cdaf9.sfr@xxxxxxxxxxxxxxxx> <4D89CA7D.8080108@xxxxxxxxxxxxxxxxxx> <alpine.LFD.2.02.1103231623450.12911@x980> <4D8B550D.5000409@xxxxxxxxxxxxxxxxxx> <alpine.LFD.2.02.1103250321480.32565@x980> <20110325180156.GC19214@xxxxxxxxxxxxxxxxxx> <alpine.LFD.2.02.1103302203490.1920@x980> <1301577536.4859.249.camel@twins> <alpine.LFD.2.02.1104010006210.2797@x980> |
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xen-devel-bounces@xxxxxxxxxxxxxxxxxxx |
On Fri, 2011-04-01 at 00:09 -0400, Len Brown wrote:
> > > Moorestown is already an example of an asymmetric system,
> > > since its deepest c-state is available on cpu0, but not on cpu1.
> > > So it needs different tables for each cpu.
> >
> > wtf are these hardware guys smoking and how the heck are we supposed to
> > schedule on such a machine? Prefer to keep cpu1 busy while idling cpu0?
>
> they are smoking micro-amps:-)
Has anybody told them that pushing lots of logic into software generally
burns more amps because it keeps the thing running longer?
> S0i3 on cpu0 can be entered only after cpu1 is already off-line,
> among other system hardware dependencies...
>
> So it makes no sense to export S0i3 as a c-state on cpu1.
>
> When cpu1 is online, the scheduler treats it as a normal SMP.
Dipankar's reply seems to address this issue well.
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