From: Milian Wolff <milian.wolff@kdab.com>
To: linux-perf-users@vger.kernel.org
Subject: perf sleep time profiling: no sched_stat_sleep events?
Date: Sat, 13 Aug 2016 00:13:37 +0200 [thread overview]
Message-ID: <4191950.GXAFRqVoOG@agathebauer> (raw)
[-- Attachment #1: Type: text/plain, Size: 984 bytes --]
Hey all,
sending this here in the hope that it may guide people in avoiding this issue
in the future:
I have encountered an issue with a recent Arch Linux Kernel (4.7), where the
the perf script to profile sleep times did not produce any output.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~
perf top -e "sched:sched_stat_*"
# wait for some time
0 sched:sched_stat_wait
0 sched:sched_stat_sleep
0 sched:sched_stat_iowait
0 sched:sched_stat_blocked
4K sched:sched_stat_runtime
~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The culprit is
~~~~~~~~~~~~~~~~~~~~~~~~~~~~
cat /proc/sys/kernel/sched_schedstats
0
~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Setting that to 1 enables the sched_stat trace points and makes the script
work again as needed.
I wonder: Could perf print a warning when the user tries to trace these events
but they are not enabled?
Thanks
--
Milian Wolff | milian.wolff@kdab.com | Software Engineer
KDAB (Deutschland) GmbH&Co KG, a KDAB Group company
Tel: +49-30-521325470
KDAB - The Qt Experts
[-- Attachment #2: smime.p7s --]
[-- Type: application/pkcs7-signature, Size: 5903 bytes --]
reply other threads:[~2016-08-12 22:13 UTC|newest]
Thread overview: [no followups] expand[flat|nested] mbox.gz Atom feed
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=4191950.GXAFRqVoOG@agathebauer \
--to=milian.wolff@kdab.com \
--cc=linux-perf-users@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.