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From: Cyrill Gorcunov <gorcunov@gmail.com>
To: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <peterz@infradead.org>,
	Stephane Eranian <eranian@google.com>,
	Frederic Weisbecker <fweisbec@gmail.com>,
	Don Zickus <dzickus@redhat.com>,
	LKML <linux-kernel@vger.kernel.org>
Subject: Re: [RFC perf,x86] P4 PMU early draft
Date: Tue, 9 Feb 2010 09:54:43 +0300	[thread overview]
Message-ID: <aa79d98a1002082254v58f2fc0jd157469b13ee9a94@mail.gmail.com> (raw)
In-Reply-To: <20100209041739.GA11280@elte.hu>

On 2/9/10, Ingo Molnar <mingo@elte.hu> wrote:
>
> * Cyrill Gorcunov <gorcunov@gmail.com> wrote:
>
>> Hi all,
>>
>> first of all the patches are NOT for any kind of inclusion. It's not ready
>>
>> yet. More likely I'm asking for glance review, ideas, criticism.
>
> A quick question: does the code produce something on a real P4? (possibly
> only running with a single event - but even that would be enough.)

not yet, a few code snippets need to be added into scheduling routine,
hope to finish this today evening

>
>> The main problem in implementing P4 PMU is that it has much more
>> restrictions for event to MSR mapping. [...]
>
> One possibly simpler approach might be to represent the P4 PMU via a maximum
> _two_ generic events only.
>

yeah, good idea!

> Last i looked at the many P4 events, i've noticed that generally you can
> create any two events. (with a few exceptions) Once you start trying to take
> advantage of the more than a dozen seemingly separate counters, additional
> non-trivial constraints apply.
>
> So if we only allowed a maximum of _two_ generic events (like say a simple
> Core2 has, so it's not a big restriction at all), we wouldnt have to map all
> the constraints, we'd only have to encode the specific event-to-MSR details.
> (which alone is quite a bit of work as well.)
>
> We could also use the new constraints code to map them all, of course - it
> will certainly be more complex to implement.
>

i thought about it, but i didn't like the result code ;) will think about it.

> Hm?
>
> 	Ingo
>

  reply	other threads:[~2010-02-09  6:54 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-02-08 18:45 [RFC perf,x86] P4 PMU early draft Cyrill Gorcunov
2010-02-08 21:56 ` Cyrill Gorcunov
2010-02-09  4:17 ` Ingo Molnar
2010-02-09  6:54   ` Cyrill Gorcunov [this message]
2010-02-09 22:39   ` Cyrill Gorcunov
2010-02-10 10:12     ` Peter Zijlstra
2010-02-10 10:38       ` Cyrill Gorcunov
2010-02-10 10:52         ` Peter Zijlstra
2010-02-10 11:23           ` Cyrill Gorcunov
2010-02-11 12:21           ` Peter Zijlstra
2010-02-11 15:22             ` Cyrill Gorcunov
2010-02-26 10:25             ` [tip:perf/core] perf_events: Simplify code by removing cpu argument to hw_perf_group_sched_in() tip-bot for Peter Zijlstra
2010-02-09  4:23 ` [RFC perf,x86] P4 PMU early draft Paul Mackerras
2010-02-09  6:57   ` Cyrill Gorcunov
2010-02-09  8:54   ` Peter Zijlstra
2010-02-09 21:13 ` Stephane Eranian
2010-02-09 21:35   ` Cyrill Gorcunov
2010-02-15 20:11 ` Robert Richter
2010-02-15 20:32   ` Cyrill Gorcunov
2010-02-17 22:14   ` Cyrill Gorcunov

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