linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Arnd Bergmann <arnd@arndb.de>
To: John Stultz <john.stultz@linaro.org>
Cc: Andy Lutomirski <luto@amacapital.net>,
	Pawel Moll <pawel.moll@arm.com>,
	Richard Cochran <richardcochran@gmail.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	Ingo Molnar <mingo@redhat.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Paul Mackerras <paulus@samba.org>,
	Arnaldo Carvalho de Melo <acme@kernel.org>,
	Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>,
	Christopher Covington <cov@codeaurora.org>,
	Namhyung Kim <namhyung@kernel.org>,
	David Ahern <dsahern@gmail.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Tomeu Vizoso <tomeu@tomeuvizoso.net>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Linux API <linux-api@vger.kernel.org>,
	Pawel Moll <mail@pawelmoll.com>
Subject: Re: [PATCH v3 0/3] perf: User/kernel time correlation and event generation
Date: Tue, 04 Nov 2014 09:01:31 +0100	[thread overview]
Message-ID: <3430954.VNaFmamXmP@wuerfel> (raw)
In-Reply-To: <CALAqxLXfy5P0kg-W7hL+Jf1iYv758+-2cTdZwsY8kAns1nvEmg@mail.gmail.com>

On Monday 03 November 2014 17:11:53 John Stultz wrote:
> I've got some thoughts on what a possible interface that wouldn't be
> awful could look like, but I'm still hesitant because I don't really
> know if exposing this sort of data is actually a good idea long term.
 
I was also thinking (while working on an unrelated patch) we could use
a system call like

int clock_getoffset(clockid_t clkid, struct timespec *offs);

that returns the current offset between CLOCK_REALTIME and the
requested timebase. It is of course racy, but so is every use
of CLOCK_REALTIME. We could also use a reference other than
CLOCK_REALTIME that might be more stable, but passing two arbitrary
clocks as input would make this much more complex to implement.

	Arnd

  parent reply	other threads:[~2014-11-04  8:02 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-11-04  0:28 [PATCH v3 0/3] perf: User/kernel time correlation and event generation Pawel Moll
2014-11-04  0:28 ` [PATCH v3 1/3] perf: Use monotonic clock as a source for timestamps Pawel Moll
2014-11-04  7:23   ` Peter Zijlstra
2014-11-04 15:25     ` Pawel Moll
2014-11-04 15:30       ` Peter Zijlstra
2014-11-04  0:28 ` [PATCH v3 2/3] perf: Userspace event Pawel Moll
2014-11-04  6:33   ` Namhyung Kim
2014-11-04 16:42     ` Pawel Moll
2014-11-04 18:40       ` Peter Zijlstra
2014-11-05  6:36         ` Namhyung Kim
2014-11-04  0:28 ` [PATCH v3 3/3] perf: Sample additional clock value Pawel Moll
2014-11-04  0:58 ` [PATCH v3 0/3] perf: User/kernel time correlation and event generation Andy Lutomirski
2014-11-04  1:11   ` John Stultz
2014-11-04  1:25     ` Andy Lutomirski
2014-11-04 15:07       ` Pawel Moll
2014-11-04  8:01     ` Arnd Bergmann [this message]
2014-11-04  8:27       ` Richard Cochran
2014-11-04 10:49         ` Thomas Gleixner
2014-11-04 16:11           ` Arnd Bergmann
2014-11-04 16:04       ` John Stultz
2014-11-04  8:24     ` Richard Cochran
2014-11-04  9:24 ` Masami Hiramatsu
2014-11-04 15:51   ` Pawel Moll
2014-11-05  8:06     ` Masami Hiramatsu

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=3430954.VNaFmamXmP@wuerfel \
    --to=arnd@arndb.de \
    --cc=acme@kernel.org \
    --cc=cov@codeaurora.org \
    --cc=dsahern@gmail.com \
    --cc=john.stultz@linaro.org \
    --cc=linux-api@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=luto@amacapital.net \
    --cc=mail@pawelmoll.com \
    --cc=masami.hiramatsu.pt@hitachi.com \
    --cc=mingo@redhat.com \
    --cc=namhyung@kernel.org \
    --cc=paulus@samba.org \
    --cc=pawel.moll@arm.com \
    --cc=peterz@infradead.org \
    --cc=richardcochran@gmail.com \
    --cc=rostedt@goodmis.org \
    --cc=tglx@linutronix.de \
    --cc=tomeu@tomeuvizoso.net \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).