From: Paul Mackerras <paulus@samba.org>
To: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Ingo Molnar <mingo@elte.hu>, Thomas Gleixner <tglx@linutronix.de>,
LKML <linux-kernel@vger.kernel.org>,
linux-arch@vger.kernel.org,
Andrew Morton <akpm@linux-foundation.org>,
Stephane Eranian <eranian@googlemail.com>,
Eric Dumazet <dada1@cosmosbay.com>,
Robert Richter <robert.richter@amd.com>,
Arjan van de Veen <arjan@infradead.org>,
Peter Anvin <hpa@zytor.com>, Steven Rostedt <rostedt@goodmis.org>,
David Miller <davem@davemloft.net>
Subject: Re: [patch 0/3] [Announcement] Performance Counters for Linux
Date: Fri, 5 Dec 2008 20:16:54 +1100 [thread overview]
Message-ID: <18744.61830.572384.96322@cargo.ozlabs.ibm.com> (raw)
In-Reply-To: <1228464216.18899.18.camel@twins>
Peter Zijlstra writes:
> 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.
Right - but the monitored task is running while the monitoring task is
running. So time is flowing for the monitored task between the two
reads done by the monitoring task, meaning that you can't actually
relate the two values you read with any precision.
Paul.
next prev parent reply other threads:[~2008-12-05 9:34 UTC|newest]
Thread overview: 68+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-12-04 23:44 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 7:16 ` Peter Zijlstra
2008-12-05 7:57 ` Paul Mackerras
2008-12-05 8:03 ` Peter Zijlstra
2008-12-05 8:07 ` David Miller
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 12:39 ` 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
2008-12-05 15:00 ` Arjan van de Ven
2008-12-05 9:16 ` Paul Mackerras [this message]
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
2008-12-05 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 ` [perfmon2] [patch 0/3] [Announcement] Performance Counters for Linux Rob Fowler
2008-12-10 17:11 ` Andi Kleen
2008-12-05 21:24 Corey Ashford
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