Message-ID: <1365092963.26858.107.camel@hornet>
Subject: Re: [RFC] perf: need to expose sched_clock to correlate user
 samples with kernel samples
From: Pawel Moll <pawel.moll@arm.com>
To: John Stultz <john.stultz@linaro.org>
Cc: Peter Zijlstra <peterz@infradead.org>, David Ahern <dsahern@gmail.com>,
        Stephane Eranian <eranian@google.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        LKML <linux-kernel@vger.kernel.org>, "mingo@elte.hu" <mingo@elte.hu>,
        Paul Mackerras <paulus@samba.org>, Anton Blanchard <anton@samba.org>,
        Will Deacon <Will.Deacon@arm.com>,
        "ak@linux.intel.com" <ak@linux.intel.com>,
        Pekka Enberg <penberg@gmail.com>, Steven Rostedt <rostedt@goodmis.org>,
        Robert Richter <robert.richter@amd.com>,
        Richard Cochran <richardcochran@gmail.com>
Date: Thu, 04 Apr 2013 17:29:23 +0100
In-Reply-To: <515C6C01.9070905@linaro.org>
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On Wed, 2013-04-03 at 18:50 +0100, John Stultz wrote:
> I get the reasoning around reusing the fd we already have, but is the 
> possibility of a dynamic chardev pathname really a big concern?

Well, in my particular development system I have no udev, so I had to
manually do "mknod". Perf syscall works out of the box. Of course one
could say it's my problem...

> I'm guessing the private_data on the perf file is already used?

Of course.

> Maybe can we extend the dynamic posix clock code to work on more then 
> just the chardev? 

The idea I'm following now is to make the dynamic clock framework even
more generic, so there could be a clock associated with an arbitrary
struct file * (the perf syscall is getting one with
anon_inode_getfile()). I don't know how to get this done yet, but I'll
give it a try and report.

Paweł


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