linux-kernel - Re: [PATCH 4/9] perf: Generic intel uncore support

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Message-ID: <1336644337.2527.95.camel@twins>
Date:	Thu, 10 May 2012 12:05:37 +0200
From:	Peter Zijlstra <a.p.zijlstra@...llo.nl>
To:	"Yan, Zheng" <zheng.z.yan@...el.com>
Cc:	mingo@...e.hu, andi@...stfloor.org, eranian@...gle.com,
	jolsa@...hat.com, ming.m.lin@...el.com,
	linux-kernel@...r.kernel.org, hpa <hpa@...or.com>
Subject: Re: [PATCH 4/9] perf: Generic intel uncore support

On Thu, 2012-05-10 at 15:34 +0800, Yan, Zheng wrote:
> 
> This code doesn't work for PCI uncore device if there are offline CPUs,
> because topology_physical_package_id() always return 0 for offline CPUs.

Hmm, that sounds wrong.. one would expect something like BAD_APICID, -1
or the correct number. hpa should we fix that?

Anyway,

> So besides the per CPU variable, we still need another data structure
> to track the uncore boxes. Do you still want to use per CPU variable?

Well you don't really need the value for offline CPUs, until they're
online right? So all you need to do is iterate all the box muck in a
hotplug handler and set the right pointer, no? (I suspect this would
need to be done in CPU_STARTING).
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