linux-kernel - [RFC] Performance Events 'Samples' report

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Message-Id: <E1PslLC-0000rj-EF@eag09.americas.sgi.com>
Date:	Thu, 24 Feb 2011 18:15:26 -0600
From:	Cliff Wickman <cpw@....com>
To:	linux-kernel@...r.kernel.org
Cc:	a.p.zijlstra@...llo.nl, paulus@...ba.org, mingo@...e.hu,
	acme@...stprotocols.net
Subject: [RFC] Performance Events 'Samples' report

From: Cliff Wickman <cpw@....com>

The perf command's report prints clock periods under the heading of 'Samples'.
Our applications people have been confused by this "Samples" heading.

perf report -n

# Overhead  Samples            Command         Shared Object                            Symbol
# ........ ..........  ...............  ....................  ................................
#
    99.41%1522136216246         pthreads  pthreads              [.] work_function
     0.33% 4980298302             perf  [kernel.kallsyms]     [k] clear_page_c
     ....

It would be more compact to print the number of samples.  And that would
be consistent with the heading.

Below is the code that displays the periods.  I don't see that the number
of samples is available here, but probably easily could be.
I presume that clock periods are derived from #samples * sample period.

perf/util/hist.c

 640 
 641         if (symbol_conf.show_nr_samples) {
 642                 if (sep)
 643                         ret += snprintf(s + ret, size - ret, "%c%" PRIu64,      *sep, period);
 644                 else
 645                         ret += snprintf(s + ret, size - ret, "%11" PRIu64,      period);
 646         }
 647 

Signed-off-by: Cliff Wickman <cpw@....com>

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