From: Peter Zijlstra <peterz@infradead.org>
To: "David S. Ahern" <daahern@cisco.com>
Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>,
Frederic Weisbecker <fweisbec@gmail.com>,
linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org,
Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH 1/2] perf tools: Add reference timestamp to perf header
Date: Mon, 13 Dec 2010 20:22:26 +0100 [thread overview]
Message-ID: <1292268146.6803.492.camel@twins> (raw)
In-Reply-To: <4D0670BF.6050403@cisco.com>
On Mon, 2010-12-13 at 12:15 -0700, David S. Ahern wrote:
> > monotonic-clock
>
> Name seems off. The 'event' is to grab time-of-day and have the 'time'
> attribute set which gives the correlation between wall-clock and perf
> timestamps.
Well, you really want CLOCK_MONOTONIC, not CLOCK_REALTIME (nothing what
so ever to do with Real-Time computing, just another brilliant POSIX
misnomer), or possibly even CLOCK_MONOTONIC_RAW.
gettimeofday() usually returns CLOCK_REALTIME which is subject to both
NTP and timezone adjustments.
CLOCK_MONOTONIC is only subject to NTP
CLOCK_MONOTONIC_RAW is neither.
At some point we'll try and have CLOCK_TRACING and provide a similar
time to user-space that we currently use for perf (using the VDSO to
avoid any actual system-calls).
next prev parent reply other threads:[~2010-12-13 19:23 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-12-08 1:54 [PATCH 0/2] perf tools: add reference timestamp and use it in time history dump David Ahern
2010-12-08 1:54 ` [PATCH 1/2] perf tools: Add reference timestamp to perf header David Ahern
2010-12-12 20:16 ` Frederic Weisbecker
2010-12-13 13:15 ` Arnaldo Carvalho de Melo
2010-12-13 16:58 ` Arnaldo Carvalho de Melo
2010-12-13 14:39 ` David S. Ahern
2010-12-13 15:54 ` Frederic Weisbecker
2010-12-13 16:48 ` Arnaldo Carvalho de Melo
2010-12-13 17:09 ` Frederic Weisbecker
2010-12-13 17:11 ` Peter Zijlstra
2010-12-13 17:13 ` Peter Zijlstra
2010-12-13 17:23 ` Frederic Weisbecker
2010-12-13 17:37 ` Peter Zijlstra
2010-12-13 17:50 ` Frederic Weisbecker
2010-12-13 17:15 ` Frederic Weisbecker
2010-12-13 17:18 ` Peter Zijlstra
2010-12-13 17:22 ` Arnaldo Carvalho de Melo
2010-12-13 17:35 ` Peter Zijlstra
2010-12-13 17:43 ` Arnaldo Carvalho de Melo
2010-12-13 17:51 ` Peter Zijlstra
2010-12-13 18:05 ` Frederic Weisbecker
2010-12-13 18:10 ` Peter Zijlstra
2010-12-13 17:47 ` Peter Zijlstra
2010-12-13 17:49 ` David S. Ahern
2010-12-13 17:57 ` Peter Zijlstra
2010-12-13 18:01 ` David S. Ahern
2010-12-13 18:06 ` Peter Zijlstra
2010-12-13 18:20 ` David S. Ahern
2010-12-13 19:08 ` Arnaldo Carvalho de Melo
2010-12-13 19:15 ` David S. Ahern
2010-12-13 19:22 ` Peter Zijlstra [this message]
2010-12-13 19:17 ` Peter Zijlstra
2010-12-13 17:48 ` Peter Zijlstra
2010-12-13 17:14 ` Arnaldo Carvalho de Melo
2010-12-13 17:36 ` David S. Ahern
2010-12-13 17:51 ` Arnaldo Carvalho de Melo
2010-12-08 1:54 ` [PATCH 2/2] perf tools: Add option to show time history of event samples David Ahern
2010-12-08 21:06 ` Arnaldo Carvalho de Melo
2010-12-12 21:32 ` Frederic Weisbecker
2010-12-09 17:18 ` [PATCH 0/2] perf tools: add reference timestamp and use it in time history dump Arnaldo Carvalho de Melo
2010-12-12 21:39 ` Frederic Weisbecker
-- strict thread matches above, loose matches on Subject: below --
2010-11-29 23:07 [PATCH 0/2] perf tools: reference timestamp and " David Ahern
2010-11-29 23:07 ` [PATCH 1/2] perf tools: add reference timestamp to perf header David Ahern
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