From: David Miller <davem@davemloft.net>
To: a.p.zijlstra@chello.nl
Cc: paulus@samba.org, mingo@elte.hu, tglx@linutronix.de,
linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org,
akpm@linux-foundation.org, eranian@googlemail.com,
dada1@cosmosbay.com, robert.richter@amd.com, arjan@infradead.org,
hpa@zytor.com, rostedt@goodmis.org
Subject: Re: [patch 0/3] [Announcement] Performance Counters for Linux
Date: Fri, 05 Dec 2008 00:07:16 -0800 (PST) [thread overview]
Message-ID: <20081205.000716.40104924.davem@davemloft.net> (raw)
In-Reply-To: <1228464216.18899.18.camel@twins>
From: Peter Zijlstra <a.p.zijlstra@chello.nl>
Date: Fri, 05 Dec 2008 09:03:36 +0100
> On Fri, 2008-12-05 at 18:57 +1100, Paul Mackerras wrote:
> > Peter Zijlstra writes:
> >
> > > So, while most people would not consider two consecutive read() ops to
> > > be close or near the same time, due to preemption and such, that is
> > > taken away by the fact that the counters are task local time based - so
> > > preemption doesn't affect thing. Right?
> >
> > I'm sorry, I don't follow the argument here. What do you mean by
> > "task local time based"?
>
> time only flows when the task is running.
These things aren't measuring time, or even just cycles, they
are measuring things like L2 cache misses, cpu cycles, and
other similar kinds of events.
So these counters are going to measure all of the damn crap
assosciated with doing the read() call as well as the real work
the task does.
That's not useful to people.
next prev parent reply other threads:[~2008-12-05 8:07 UTC|newest]
Thread overview: 74+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-12-04 23:44 [patch 0/3] [Announcement] Performance Counters for Linux Thomas Gleixner
2008-12-04 23:44 ` [patch 1/3] performance counters: core code Thomas Gleixner
2008-12-05 10:55 ` Paul Mackerras
2008-12-05 11:20 ` Ingo Molnar
2008-12-04 23:44 ` [patch 2/3] performance counters: documentation Thomas Gleixner
2008-12-05 0:33 ` Paul Mackerras
2008-12-05 0:37 ` David Miller
2008-12-05 2:50 ` Arjan van de Ven
2008-12-05 3:26 ` David Miller
2008-12-05 2:33 ` Andi Kleen
2008-12-04 23:45 ` [patch 3/3] performance counters: x86 support Thomas Gleixner
2008-12-05 0:22 ` [patch 0/3] [Announcement] Performance Counters for Linux Paul Mackerras
2008-12-05 6:31 ` Ingo Molnar
2008-12-05 7:02 ` Arjan van de Ven
2008-12-05 7:52 ` David Miller
2008-12-05 7:03 ` Ingo Molnar
2008-12-05 7:03 ` Ingo Molnar
2008-12-05 7:16 ` Peter Zijlstra
2008-12-05 7:57 ` Paul Mackerras
2008-12-05 8:03 ` Peter Zijlstra
2008-12-05 8:07 ` David Miller [this message]
2008-12-05 8:11 ` Ingo Molnar
2008-12-05 8:17 ` David Miller
2008-12-05 8:24 ` Ingo Molnar
2008-12-05 8:27 ` David Miller
2008-12-05 8:42 ` Ingo Molnar
2008-12-05 8:49 ` David Miller
2008-12-05 12:13 ` Ingo Molnar
2008-12-05 12:13 ` Ingo Molnar
2008-12-05 12:39 ` Andi Kleen
2008-12-05 20:08 ` David Miller
2008-12-10 3:48 ` Paul Mundt
2008-12-10 4:42 ` Paul Mackerras
2008-12-10 8:43 ` Mikael Pettersson
2008-12-10 10:28 ` Andi Kleen
2008-12-10 10:23 ` Paul Mundt
2008-12-10 11:03 ` Andi Kleen
2008-12-10 11:03 ` Andi Kleen
2008-12-10 10:28 ` Andi Kleen
2008-12-05 15:00 ` Arjan van de Ven
2008-12-05 9:16 ` Paul Mackerras
2008-12-05 7:57 ` David Miller
2008-12-05 8:18 ` Ingo Molnar
2008-12-05 8:20 ` David Miller
2008-12-05 7:54 ` Paul Mackerras
2008-12-05 8:08 ` Ingo Molnar
2008-12-05 8:15 ` David Miller
2008-12-05 13:25 ` Ingo Molnar
2008-12-05 9:10 ` Paul Mackerras
2008-12-05 12:07 ` Ingo Molnar
2008-12-06 0:05 ` Paul Mackerras
2008-12-06 1:23 ` Mikael Pettersson
2008-12-06 12:34 ` Peter Zijlstra
2008-12-07 5:15 ` Paul Mackerras
2008-12-08 7:18 ` stephane eranian
2008-12-08 11:11 ` Ingo Molnar
2008-12-08 11:58 ` David Miller
2008-12-09 0:21 ` stephane eranian
2008-12-09 0:21 ` stephane eranian
2008-12-05 0:22 ` H. Peter Anvin
2008-12-05 0:43 ` Paul Mackerras
2008-12-05 1:12 ` David Miller
2008-12-05 6:10 ` Ingo Molnar
2008-12-05 7:50 ` David Miller
2008-12-05 9:34 ` Paul Mackerras
2008-12-05 10:41 ` Ingo Molnar
2008-12-05 10:05 ` Ingo Molnar
2008-12-05 3:30 ` Andrew Morton
2008-12-06 2:36 ` stephane eranian
2008-12-08 2:12 ` [perfmon2] [patch 0/3] [Announcement] Performance Counters forLinux Dan Terpstra
2008-12-10 16:27 ` [patch 0/3] [Announcement] Performance Counters for Linux Rob Fowler
2008-12-10 16:27 ` [perfmon2] " Rob Fowler
2008-12-10 17:11 ` Andi Kleen
2008-12-10 17:11 ` Andi Kleen
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