From: David Ahern <daahern@cisco.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org,
acme@ghostprotocols.net, mingo@elte.hu, fweisbec@gmail.com,
paulus@samba.org, tglx@linutronix.de
Subject: Re: [PATCH 3/6] perf record: add time-of-day option
Date: Tue, 01 Mar 2011 09:09:48 -0700 [thread overview]
Message-ID: <4D6D1A4C.1090009@cisco.com> (raw)
In-Reply-To: <1298995250.5226.882.camel@laptop>
On 03/01/2011 09:00 AM, Peter Zijlstra wrote:
> On Tue, 2011-03-01 at 08:41 -0700, David Ahern wrote:
>
>> realtime-clock counter is created with a period N. How do you correlate
>> perf_clock to time-of-day until now + N?
>
> You scan fwd? Since its at most N time ahead you're scanning fwd its
> still constant time.
So I potentially scan a multi-gigabyte file looking for a single event
-- that may not even exist. From a usability perspective the time string
should appear if the clock event exists and not if it does not exist.
This should happen automatically.
>
> Thing is, I'm really not convinced this is a very useful ioctl() in
> generic, and ioctl()s really need a good justification to add.
>
I did not code it create samples of a realtime-clock event; I coded it
to add an event to the stream on demand -- whatever event the fd is tied to.
David
next prev parent reply other threads:[~2011-03-01 16:09 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-02-28 3:52 [PATCH 0/6 v3] perf events: Add realtime clock event, time-of-day strings to script output David Ahern
2011-02-28 3:52 ` [PATCH 1/6] perf events: Introduce realtime clock event David Ahern
2011-02-28 3:52 ` [PATCH 2/6] perf events: plumbing for PERF_SAMPLE_READ and read_format David Ahern
2011-02-28 3:52 ` [PATCH 3/6] perf record: add time-of-day option David Ahern
2011-03-01 14:29 ` Peter Zijlstra
2011-03-01 14:35 ` David Ahern
2011-03-01 15:35 ` Peter Zijlstra
2011-03-01 15:41 ` David Ahern
2011-03-01 16:00 ` Peter Zijlstra
2011-03-01 16:09 ` David Ahern [this message]
2011-03-01 16:37 ` Peter Zijlstra
2011-03-01 16:45 ` David Ahern
2011-03-01 17:07 ` Arnaldo Carvalho de Melo
2011-03-01 17:09 ` Arnaldo Carvalho de Melo
2011-03-01 22:28 ` Peter Zijlstra
2011-03-01 22:35 ` David Ahern
2011-03-02 14:16 ` Thomas Gleixner
2011-03-02 14:28 ` David Ahern
2011-03-02 17:28 ` Thomas Gleixner
2011-03-03 14:29 ` David Ahern
2011-03-03 8:51 ` Ingo Molnar
2011-03-03 14:33 ` David Ahern
2011-02-28 3:52 ` [PATCH 4/6] perf script: dump software events too David Ahern
2011-03-01 14:09 ` Frederic Weisbecker
2011-03-01 14:18 ` David Ahern
2011-03-01 15:11 ` Frederic Weisbecker
2011-03-01 16:11 ` David Ahern
2011-03-01 16:24 ` Frederic Weisbecker
2011-03-01 16:49 ` Arnaldo Carvalho de Melo
2011-02-28 3:52 ` [PATCH 5/6] perf script: Prepend lines with time-of-day string David Ahern
2011-02-28 3:52 ` [PATCH 6/6] perf stat: treat realtime-clock as nsec counter David Ahern
2011-02-28 3:55 ` [PATCH 0/6 v3] perf events: Add realtime clock event, time-of-day strings to script output David Ahern
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