From: Michael Ellerman <michael@ellerman.id.au>
To: Scott Wood <scottwood@freescale.com>
Cc: mahesh@linux.vnet.ibm.com, linuxppc-dev@ozlabs.org,
Anton Blanchard <anton@samba.org>
Subject: Re: [PATCH] powerpc: Export PIR data through sysfs
Date: Wed, 09 Nov 2011 17:51:24 +1100 [thread overview]
Message-ID: <1320821484.9376.9.camel@concordia> (raw)
In-Reply-To: <4EB96002.5030605@freescale.com>
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On Tue, 2011-11-08 at 10:59 -0600, Scott Wood wrote:
> On 11/08/2011 12:58 AM, Ananth N Mavinakayanahalli wrote:
> > On Mon, Nov 07, 2011 at 11:18:32AM -0600, Scott Wood wrote:
> >> What use does userspace have for this? If you want to return the
> >> currently executing CPU (which unless you're pinned could change as soon
> >> as the value is read...), why not just return smp_processor_id() or
> >> hard_smp_processor_id()?
> >
> > Its not just the current cpu. Decoding PIR can tell you the core id,
> > thread id in case of SMT, and this information can be used by userspace
> > apps to set affinities, etc.
>
> Wouldn't it make more sense to expose the thread to core mappings in a
> general way, not tied to hardware or what thread we're currently running on?
AFAIK that is already available in /sys/devices/system/cpu/cpuX/topology
cheers
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prev parent reply other threads:[~2011-11-09 6:51 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-11-07 4:47 [PATCH] powerpc: Export PIR data through sysfs Ananth N Mavinakayanahalli
2011-11-07 17:18 ` Scott Wood
2011-11-08 6:58 ` Ananth N Mavinakayanahalli
2011-11-08 16:59 ` Scott Wood
2011-11-09 4:41 ` Ananth N Mavinakayanahalli
2011-11-09 15:48 ` Scott Wood
2011-11-10 8:48 ` Ananth N Mavinakayanahalli
2011-11-11 4:18 ` Benjamin Herrenschmidt
2011-11-11 4:47 ` Ananth N Mavinakayanahalli
2011-11-11 5:58 ` [PATCH V2] " Ananth N Mavinakayanahalli
2011-11-09 6:51 ` Michael Ellerman [this message]
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