linux-kernel - Re: [PATCH 2/2] x86: UV hardware performance counter and topology access

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Message-ID: <20091001074630.GA6738@elte.hu>
Date:	Thu, 1 Oct 2009 09:46:30 +0200
From:	Ingo Molnar <mingo@...e.hu>
To:	Russ Anderson <rja@....com>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Paul Mackerras <paulus@...ba.org>,
	Frédéric Weisbecker <fweisbec@...il.com>,
	Steven Rostedt <rostedt@...dmis.org>
Cc:	linux-kernel@...r.kernel.org, hpa@...or.com,
	Cliff Wickman <cpw@....com>
Subject: Re: [PATCH 2/2] x86: UV hardware performance counter and topology
	access

* Russ Anderson <rja@....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
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