From: Ingo Molnar <mingo@kernel.org>
To: David Ahern <dsahern@gmail.com>
Cc: acme@ghostprotocols.net, linux-kernel@vger.kernel.org,
peterz@infradead.org, Robert Richter <robert.richter@amd.com>
Subject: Re: [PATCH 3/3 v2] perf tool: give user better message if precise is not supported
Date: Fri, 14 Sep 2012 07:43:44 +0200 [thread overview]
Message-ID: <20120914054344.GB9043@gmail.com> (raw)
In-Reply-To: <1347569955-54626-4-git-send-email-dsahern@gmail.com>
* David Ahern <dsahern@gmail.com> wrote:
> Platforms (e.g., VM's) without support for precise mode get a confusing
> error message. e.g.,
> $ perf record -e cycles:p -a -- sleep 1
>
> Error: sys_perf_event_open() syscall returned with 95 (Operation not
> supported). /bin/dmesg may provide additional information.
>
> No hardware sampling interrupt available. No APIC? If so then you can
> boot the kernel with the "lapic" boot parameter to force-enable it.
> sleep: Terminated
>
> which is not clear that precise mode might be the root problem. With this
> patch:
>
> $ perf record -e cycles:p -fo /tmp/perf.data -- sleep 1
> Error:
> 'precise' request may not be supported. Try removing 'p' modifier
> sleep: Terminated
>
> v2: softened message to 'may not be' supported per Robert's suggestion
Well, either it's supported on this machine or it's not - why
does the text have to be so unsure about it?
We use computers to increase determinism, not to insert extra
uncertainty! ;-)
Thanks,
Ingo
next prev parent reply other threads:[~2012-09-14 5:43 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-09-13 20:59 [PATCH 0/3 v3] perf: precise mode and exclude_guest David Ahern
2012-09-13 20:59 ` [PATCH 1/3] perf tool: precise mode requires exclude_guest David Ahern
2012-10-20 0:55 ` [tip:perf/urgent] perf tool: Precise " tip-bot for David Ahern
2012-09-13 20:59 ` [PATCH 2/3] perf: require exclude_guest to use PEBS - kernel side enforcement David Ahern
2012-10-20 0:56 ` [tip:perf/urgent] perf: Require " tip-bot for Peter Zijlstra
2012-09-13 20:59 ` [PATCH 3/3 v2] perf tool: give user better message if precise is not supported David Ahern
2012-09-14 5:43 ` Ingo Molnar [this message]
2012-09-14 11:13 ` David Ahern
2012-09-14 11:36 ` Ingo Molnar
2012-09-14 11:43 ` David Ahern
2012-09-14 18:00 ` Arnaldo Carvalho de Melo
2012-09-14 18:07 ` Peter Zijlstra
2012-09-14 20:05 ` Ingo Molnar
2012-09-14 20:11 ` Ingo Molnar
2012-09-14 21:26 ` Peter Zijlstra
2012-09-17 7:11 ` Ingo Molnar
2012-10-25 8:01 ` [tip:perf/core] perf tools: Give " tip-bot for David Ahern
2012-09-26 1:24 ` [PATCH 0/3 v3] perf: precise mode and exclude_guest David Ahern
2012-10-09 15:08 ` David Ahern
-- strict thread matches above, loose matches on Subject: below --
2012-09-12 15:16 [PATCH 0/3 v2] " David Ahern
2012-09-12 15:16 ` [PATCH 3/3 v2] perf tool: give user better message if precise is not supported David Ahern
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