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Date: Thu, 1 Oct 2009 09:46:30 +0200
From: Ingo Molnar <mingo@elte.hu>
To: Russ Anderson <rja@sgi.com>, Peter Zijlstra <a.p.zijlstra@chello.nl>,
       Paul Mackerras <paulus@samba.org>,
       =?iso-8859-1?Q?Fr=E9d=E9ric?= Weisbecker <fweisbec@gmail.com>,
       Steven Rostedt <rostedt@goodmis.org>
Cc: linux-kernel@vger.kernel.org, hpa@zytor.com, Cliff Wickman <cpw@sgi.com>
Subject: Re: [PATCH 2/2] x86: UV hardware performance counter and topology
	access
Message-ID: <20091001074630.GA6738@elte.hu>
References: <20090930210531.GC12090@sgi.com>
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* Russ Anderson <rja@sgi.com> wrote:

> Adds device named "/dev/uv_hwperf" that supports an ioctl interface
> to call down into BIOS to read/write memory mapped performance
> monitoring registers.

That's not acceptable - please integrate this with perf events properly. 
See arch/x86/kernel/cpu/perf_event.c for details.

Precisely what kinds of events are being exposed by the UV BIOS 
interface? Also, how does the BIOS get them? The BIOS should be left out 
of that - the PMU driver should know about and access hardware registers 
directly.

If any of this needs enhancements in kernel/perf_event.c we'll be glad 
to help out.

	Ingo