linux-kernel - Re: [PATCH 2/5] perf: generic intel uncore support

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Date:	Tue, 03 Apr 2012 00:16:48 +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,
	linux-kernel@...r.kernel.org, ming.m.lin@...el.com
Subject: Re: [PATCH 2/5] perf: generic intel uncore support

On Sun, 2012-04-01 at 11:11 +0800, Yan, Zheng wrote:
> > So what's up with all this box->lock business.. why does that lock
> > exist?
> 
> If user doesn't provide the "-C x" option to the perf tool, multiple cpus
> will try adding/deleting events at the same time. 

Right, however:

> > Aside from all this, there's still the problem that you don't place all
> > events for a particular phys_id onto a single cpu. It doesn't matter
> > which cpu in that package it is, but all events should go to the same.
> > 
> > This means that on unplug of that cpu, you have to migrate all these
> > events etc..
> 
> Any hints how to do this. I'm afraid it requires big changes to perf core.

Yes it'll need some core changes, but I don't think I'll be too bad,
I'll try and write up something soonish.. 

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