linux-kernel - Re: [RFC PATCH 2/3 v2] perf: Implement Nehalem uncore pmu

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Date:	Fri, 26 Nov 2010 12:24:12 +0100
From:	Peter Zijlstra <a.p.zijlstra@...llo.nl>
To:	Stephane Eranian <eranian@...gle.com>
Cc:	Lin Ming <lin@...g.vg>, Lin Ming <ming.m.lin@...el.com>,
	Ingo Molnar <mingo@...e.hu>, Andi Kleen <andi@...stfloor.org>,
	lkml <linux-kernel@...r.kernel.org>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Arjan van de Ven <arjan@...radead.org>
Subject: Re: [RFC PATCH 2/3 v2] perf: Implement Nehalem uncore pmu

On Fri, 2010-11-26 at 09:18 +0100, Stephane Eranian wrote:

> In the perf_event model, given that any one of the 4 cores can be used
> to program uncore events, you have no choice but to broadcast to all
> 4 cores. Each has to demultiplex and figure out which of its counters
> have overflowed.

Not really, you can redirect all these events to the first online cpu of
the node.

You can re-write event->cpu in pmu::event_init(), and register cpu
hotplug notifiers to migrate the state around.


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