From: Mel Gorman <mgorman@techsingularity.net>
To: Jiri Olsa <jolsa@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>,
LKML <linux-kernel@vger.kernel.org>
Subject: perf stat stddev reporting broken since "perf stat: Introduce read_counters function"
Date: Mon, 18 Jan 2016 17:59:46 +0000 [thread overview]
Message-ID: <20160118175946.GC10802@techsingularity.net> (raw)
I noticed that perf stat in 4.4 is not printing stddev figures as
expected and bisected it to commit 106a94a0f8c2 ("perf stat: Introduce
read_counters function").
# Kernel 4.4
# make clean && make prefix=/usr && ./perf stat -r 5 sleep 1
Performance counter stats for 'sleep 1' (5 runs):
0.466683 task-clock (msec) # 0.000 CPUs utilized
1 context-switches # 0.002 M/sec
1 cpu-migrations # 0.002 M/sec
66 page-faults # 0.144 M/sec
1,630,220 cycles # 3.562 GHz
<not supported> stalled-cycles-frontend
<not supported> stalled-cycles-backend
902,686 instructions # 0.66 insns per cycle
185,692 branches # 405.786 M/sec
8,640 branch-misses # 4.63% of all branches
1.000855883 seconds time elapsed ( +- 0.01% )
# git checkout 106a94a0f8c207ef4113ce7e32f34a00b3b174e7^
Performance counter stats for 'sleep 1' (5 runs):
0.397939 task-clock (msec) # 0.000 CPUs utilized ( +- 3.37% )
1 context-switches # 0.003 M/sec
0 cpu-migrations # 0.000 K/sec
67 page-faults # 0.169 M/sec ( +- 0.56% )
1,360,763 cycles # 3.420 GHz ( +- 2.14% )
<not supported> stalled-cycles-frontend
<not supported> stalled-cycles-backend
903,901 instructions # 0.66 insns per cycle ( +- 0.24% )
186,472 branches # 468.595 M/sec ( +- 0.29% )
8,599 branch-misses # 4.61% of all branches ( +- 0.77% )
1.000761882 seconds time elapsed ( +- 0.00% )
# git checkout 106a94a0f8c207ef4113ce7e32f34a00b3b174e7
Performance counter stats for 'sleep 1' (5 runs):
0.583178 task-clock (msec) # 0.001 CPUs utilized
1 context-switches # 0.002 M/sec
0 cpu-migrations # 0.000 K/sec
67 page-faults # 0.141 M/sec
1,224,416 cycles # 2.585 GHz
<not supported> stalled-cycles-frontend
<not supported> stalled-cycles-backend
892,568 instructions # 0.68 insns per cycle
184,975 branches # 390.554 M/sec
8,512 branch-misses # 4.57% of all branches
1.000889249 seconds time elapsed ( +- 0.01% )
I checked and current master in Linus' tree is also broken. Is this
change in documented perf stat behaviour intentional?
--
Mel Gorman
SUSE Labs
next reply other threads:[~2016-01-18 17:59 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-01-18 17:59 Mel Gorman [this message]
2016-01-19 7:42 ` perf stat stddev reporting broken since "perf stat: Introduce read_counters function" Jiri Olsa
2016-01-19 8:16 ` Jiri Olsa
2016-01-19 9:38 ` Mel Gorman
2016-01-19 9:57 ` Jiri Olsa
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20160118175946.GC10802@techsingularity.net \
--to=mgorman@techsingularity.net \
--cc=acme@redhat.com \
--cc=jolsa@kernel.org \
--cc=linux-kernel@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.