From: Andi Kleen <ak@linux.intel.com>
To: Adrian Hunter <adrian.hunter@intel.com>,
Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>, linux-kernel@vger.kernel.org
Subject: Re: [PATCH V2 3/6] perf intel-pt: Support itrace A option to approximate IPC
Date: Tue, 26 Oct 2021 10:03:02 -0700 [thread overview]
Message-ID: <a37ede61-c607-4fcf-2be4-12b83cdf0d7e@linux.intel.com> (raw)
In-Reply-To: <20211026090152.357591-4-adrian.hunter@intel.com>
On 10/26/2021 2:01 AM, Adrian Hunter wrote:
> Normally, for cycle-acccurate mode, IPC values are an exact number of
> instructions and cycles. Due to the granularity of timestamps, that happens
> only when a CYC packet correlates to the event.
>
> Support the itrace 'A' option, to use instead, the number of cycles
> associated with the current timestamp. This provides IPC information for
> every change of timestamp, but at the expense of accuracy.
Can you expand a bit what exactly the accuracy loss it?
Would be good to describe that in the manpage too.
next prev parent reply other threads:[~2021-10-26 17:03 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-26 9:01 [PATCH V2 0/6] perf dlfilter: Add dlfilter-show-cycles Adrian Hunter
2021-10-26 9:01 ` [PATCH V2 1/6] perf auxtrace: Add missing Z option to ITRACE_HELP Adrian Hunter
2021-10-26 9:01 ` [PATCH V2 2/6] perf auxtrace: Add itrace A option to approximate IPC Adrian Hunter
2021-10-26 9:01 ` [PATCH V2 3/6] perf intel-pt: Support " Adrian Hunter
2021-10-26 17:03 ` Andi Kleen [this message]
2021-10-26 9:01 ` [PATCH V2 4/6] perf dlfilter: Add dlfilter-show-cycles Adrian Hunter
2021-10-26 9:01 ` [PATCH V2 5/6] perf auxtrace: Add itrace d+o option to direct debug log to stdout Adrian Hunter
2021-10-26 9:01 ` [PATCH V2 6/6] perf intel-pt: Support " Adrian Hunter
[not found] ` <dd9f91af-8b74-bf75-b3a4-c3826be7b190@linux.intel.com>
2021-10-27 18:59 ` Arnaldo Carvalho de Melo
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