Re: [PATCH] perf, record: Add clockid parameter

From: Stephane Eranian <eranian@google.com>
To: David Ahern <dsahern@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
	Arnaldo Carvalho de Melo <acme@redhat.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Jiri Olsa <jolsa@redhat.com>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	LKML <linux-kernel@vger.kernel.org>,
	John Stultz <john.stultz@linaro.org>,
	"H. Peter Anvin" <hpa@zytor.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Ingo Molnar <mingo@kernel.org>
Subject: Re: [PATCH] perf, record: Add clockid parameter
Date: Mon, 30 Mar 2015 12:43:25 -0700	[thread overview]
Message-ID: <CABPqkBT8eQM0WVcEqE-wKO06tVtYAF02Wn_r3eKs3j9vW53m8Q@mail.gmail.com> (raw)
In-Reply-To: <5519A6D8.9060806@gmail.com>

On Mon, Mar 30, 2015 at 12:41 PM, David Ahern <dsahern@gmail.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.