linux-kernel - Re: [PATCH] perf, record: Add clockid parameter

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Date:	Mon, 30 Mar 2015 12:43:25 -0700
From:	Stephane Eranian <eranian@...gle.com>
To:	David Ahern <dsahern@...il.com>
Cc:	Peter Zijlstra <peterz@...radead.org>,
	Arnaldo Carvalho de Melo <acme@...hat.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Jiri Olsa <jolsa@...hat.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	LKML <linux-kernel@...r.kernel.org>,
	John Stultz <john.stultz@...aro.org>,
	"H. Peter Anvin" <hpa@...or.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Ingo Molnar <mingo@...nel.org>
Subject: Re: [PATCH] perf, record: Add clockid parameter

On Mon, Mar 30, 2015 at 12:41 PM, David Ahern <dsahern@...il.com> wrote:
> On 3/30/15 1:33 PM, Peter Zijlstra wrote:
>>
>> On Mon, Mar 30, 2015 at 11:24:12AM -0600, David Ahern wrote:
>>>
>>> This works but the result is not always intuitive as to why it failed.
>>>
>>> On a kernel that does not support the clock id you get:
>>>      $ perf sched record -k mono -- sleep 1
>>>      Error:
>>>      clockid not supported.
>>>
>>> And on a kernel that supports clockid but not for NMI:
>>>
>>>      $ perf record -k realtime -a -- sleep 1
>>>      Error:
>>>      clockid not supported.
>>>
>>>      --> H/W counters so realtime is not allowed
>>>
>>> Same message though different root causes.
>>
>>
>> Heh, ok I can fudge that :-)
>>
>
> What about having the kernel return 'not supported' error for the latter --
> H/W counters with unsafe clock?

I have reassembled all the pieces from Peter's patch. I will post it
with V6 of the JIT patches today.
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