linux-kernel - Re: [PATCH 0/4] perf: add support for profiling jitted code

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Message-ID: <CABPqkBR-mg00JS5KF+9oGg=+Xo+eprYSk5WYEg0P2w30JGXCoQ@mail.gmail.com>
Date:	Wed, 11 Feb 2015 08:18:37 -0500
From:	Stephane Eranian <eranian@...gle.com>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Arnaldo Carvalho de Melo <acme@...hat.com>,
	"mingo@...e.hu" <mingo@...e.hu>,
	"ak@...ux.intel.com" <ak@...ux.intel.com>,
	Jiri Olsa <jolsa@...hat.com>,
	Namhyung Kim <namhyung@...nel.org>,
	Rose Belcher <cel@...ibm.com>,
	Sukadev Bhattiprolu <sukadev@...ux.vnet.ibm.com>,
	Sonny Rao <sonnyrao@...omium.org>,
	John Mccutchan <johnmccutchan@...gle.com>,
	David Ahern <dsahern@...il.com>
Subject: Re: [PATCH 0/4] perf: add support for profiling jitted code

Peter,

On Wed, Feb 11, 2015 at 6:39 AM, Peter Zijlstra <peterz@...radead.org> wrote:
> On Wed, Feb 11, 2015 at 12:42:41AM +0100, Stephane Eranian wrote:
>> To enable synchronization of the runtime MMAPs with those recorded by
>> the kernel on behalf of the perf tool, the runtime needs to timestamp
>> any record in the dump file using the same time source. The current
>> patch series is relying on Sonny Rao's posix-clock patch series
>> posted on LKML in 2013. The link to the patches is:
>>       https://lkml.org/lkml/2013/12/6/1044
>>
>
> At least for x86 you could use something like this:
>
>   lkml.kernel.org/r/aa2dd2e4f1e9f2225758be5ba00f14d6909a8ce1.1423180257.git.shli@...com
>
> We can re-create the perf_clock() from the tsc with the mult, shift and
> offset provided in the perf userpage.

I had forgotten that I had modified Sonny's patch to use sched_clock(). I will
post V2 using David Ahern's driver instead.

But, we need a portable solution, there are jitted environment on other
architectures.
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