From: "Darren Hart" <darren@dvhart.com>
To: "Mathieu Desnoyers" <compudj@krystal.dyndns.org>
Cc: "Roland Dreier" <rdreier@cisco.com>,
"Linus Torvalds" <torvalds@linux-foundation.org>,
"Masami Hiramatsu" <mhiramat@redhat.com>,
"Martin Bligh" <mbligh@google.com>,
"Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>,
"Thomas Gleixner" <tglx@linutronix.de>,
"Steven Rostedt" <rostedt@goodmis.org>,
"Frank Ch. Eigler" <fche@redhat.com>,
systemtap-ml <systemtap@sources.redhat.com>
Subject: Re: Unified tracing buffer
Date: Tue, 23 Sep 2008 02:27:00 -0000 [thread overview]
Message-ID: <e17d46420809221926g1396fbb4id5b9c934bad1d96e@mail.gmail.com> (raw)
In-Reply-To: <20080923020216.GC24937@Krystal>
On Mon, Sep 22, 2008 at 7:02 PM, Mathieu Desnoyers <compudj@krystal.dyndns.org>
> So only in the specific case of instrumentation of things like locking,
> where it is possible to insure that instrumentation is synchronized with
> the instrumented operation, does it make a difference to choose the TSC
> (which implies a slight delta between the TSCs due to cache line delays
> at synchronization and delay due to TSCs drifts caused by temperature)
> over an atomic increment.
>
Hrm, i think that overlooks the other reason to use a time based counter over
an atomic increment: you might care about time. Perhaps one might be less
concerned with actual order tightly grouped events and more concerned with the
actual time delta between more temporally distant events. In that case, using
a clocksource would still be valuable. Although admitedtly the caller could
embed that in their payload, but since we seem to agree we need some kind of
counter, the time-based counter appears to be the most flexible.
Thanks,
--
Darren Hart
next prev parent reply other threads:[~2008-09-23 2:27 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <33307c790809191433w246c0283l55a57c196664ce77@mail.gmail.com>
2008-09-22 19:47 ` Masami Hiramatsu
2008-09-22 20:14 ` Martin Bligh
2008-09-22 22:27 ` Masami Hiramatsu
2008-09-22 23:12 ` Darren Hart
2008-09-23 0:06 ` Masami Hiramatsu
2008-09-22 23:17 ` Martin Bligh
2008-09-23 0:07 ` Masami Hiramatsu
2008-09-23 0:13 ` Martin Bligh
2008-09-23 14:51 ` Masami Hiramatsu
2008-09-23 15:09 ` Mathieu Desnoyers
2008-09-23 15:32 ` Masami Hiramatsu
2008-09-23 16:02 ` Linus Torvalds
2008-09-23 17:07 ` Masami Hiramatsu
2008-09-23 17:33 ` Thomas Gleixner
2008-09-23 19:03 ` Masami Hiramatsu
2008-09-23 19:37 ` Thomas Gleixner
2008-09-23 19:39 ` Martin Bligh
2008-09-23 19:42 ` Thomas Gleixner
2008-09-23 19:51 ` Martin Bligh
2008-09-23 20:05 ` Thomas Gleixner
2008-09-23 21:02 ` Martin Bligh
2008-09-23 20:06 ` Masami Hiramatsu
2008-09-23 20:09 ` Thomas Gleixner
2008-09-23 15:48 ` Linus Torvalds
2008-09-23 0:41 ` Linus Torvalds
2008-09-23 1:28 ` Roland Dreier
2008-09-23 1:40 ` Steven Rostedt
2008-09-23 2:08 ` Mathieu Desnoyers
2008-09-23 2:27 ` Darren Hart [this message]
2008-09-23 2:32 ` Mathieu Desnoyers
2008-09-23 3:29 ` Linus Torvalds
2008-09-23 3:42 ` Mathieu Desnoyers
2008-09-23 4:06 ` Linus Torvalds
2008-09-23 3:44 ` Steven Rostedt
2008-09-23 4:12 ` Masami Hiramatsu
2008-09-23 4:18 ` Martin Bligh
2008-09-23 15:25 ` Masami Hiramatsu
2008-09-23 10:54 ` Steven Rostedt
2008-09-23 4:20 ` Linus Torvalds
2008-09-23 14:13 ` Mathieu Desnoyers
2008-09-23 2:31 ` Mathieu Desnoyers
2008-09-23 3:07 ` Masami Hiramatsu
2008-09-23 14:38 ` KOSAKI Motohiro
2008-09-23 15:04 ` Frank Ch. Eigler
2008-09-23 15:23 ` Masami Hiramatsu
2008-09-23 18:04 ` KOSAKI Motohiro
2008-09-23 18:29 ` Martin Bligh
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