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From: Adrian Hunter <adrian.hunter@intel.com>
To: Andi Kleen <ak@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>,
	Jiri Olsa <jolsa@redhat.com>,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 8/9] perf intel-pt: Update documentation about itrace G and L options
Date: Thu, 30 Apr 2020 08:36:42 +0300	[thread overview]
Message-ID: <0938999b-00c0-25cf-9a87-a7abc1cbac1c@intel.com> (raw)
In-Reply-To: <20200429230356.GB874567@tassilo.jf.intel.com>

On 30/04/20 2:03 am, Andi Kleen wrote:
>> +One caveat with the G and L options is that they work poorly with "Large PEBS".
>> +Large PEBS means PEBS records will be accumulated by hardware and the written
>> +into the event buffer in one go.  That reduces interrupts, but can give very
>> +late timestamps.  Because the Intel PT trace is synchronized by timestamps,
> 
> Are you refering to Broadwell here?

I was testing on Coffee Lake

> 
> On Skylake/Goldmont the PEBS event contains the TSC and the time stamp reported by
> perf should report the time the event was sampled based on that TSC. 
> Or is that not working for some reason?

I guess it is not working like that, but perf tools would probably need
special rules to sort the events because the they would break the rules of
PERF_RECORD_FINISHED_ROUND, wouldn't they?


  reply	other threads:[~2020-04-30  5:36 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-04-29 15:07 [PATCH 0/9] perf intel-pt: Add support for synthesizing branch stacks for regular events Adrian Hunter
2020-04-29 15:07 ` [PATCH 1/9] perf thread-stack: Add branch stack support Adrian Hunter
2020-05-08 13:04   ` [tip: perf/core] " tip-bot2 for Adrian Hunter
2020-04-29 15:07 ` [PATCH 2/9] perf intel-pt: Consolidate thread-stack use condition Adrian Hunter
2020-05-08 13:04   ` [tip: perf/core] " tip-bot2 for Adrian Hunter
2020-04-29 15:07 ` [PATCH 3/9] perf intel-pt: Change branch stack support to use thread-stacks Adrian Hunter
2020-05-08 13:04   ` [tip: perf/core] " tip-bot2 for Adrian Hunter
2020-04-29 15:07 ` [PATCH 4/9] perf auxtrace: Add option to synthesize branch stack for regular events Adrian Hunter
2020-05-08 13:04   ` [tip: perf/core] " tip-bot2 for Adrian Hunter
2020-04-29 15:07 ` [PATCH 5/9] perf evsel: Add support for synthesized branch stack sample type Adrian Hunter
2020-05-08 13:04   ` [tip: perf/core] " tip-bot2 for Adrian Hunter
2020-04-29 15:07 ` [PATCH 6/9] perf thread-stack: Add thread_stack__br_sample_late() Adrian Hunter
2020-05-08 13:04   ` [tip: perf/core] " tip-bot2 for Adrian Hunter
2020-04-29 15:07 ` [PATCH 7/9] perf intel-pt: Add support for synthesizing branch stacks for regular events Adrian Hunter
2020-05-08 13:04   ` [tip: perf/core] " tip-bot2 for Adrian Hunter
2020-04-29 15:07 ` [PATCH 8/9] perf intel-pt: Update documentation about itrace G and L options Adrian Hunter
2020-04-29 23:03   ` Andi Kleen
2020-04-30  5:36     ` Adrian Hunter [this message]
2020-04-30 12:28       ` Andi Kleen
2020-05-08 13:04   ` [tip: perf/core] " tip-bot2 for Adrian Hunter
2020-04-29 15:07 ` [PATCH 9/9] perf intel-pt: Update documentation about using /proc/kcore Adrian Hunter
2020-05-08 13:04   ` [tip: perf/core] " tip-bot2 for Adrian Hunter
2020-04-29 18:29 ` [PATCH 0/9] perf intel-pt: Add support for synthesizing branch stacks for regular events Arnaldo Carvalho de Melo

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