From: Cyril Hrubis <chrubis@suse.cz>
To: ltp@lists.linux.it
Subject: [LTP] [PATCH v2] [RFC] pselect01: Tune thresholds
Date: Tue, 23 May 2017 11:16:08 +0200 [thread overview]
Message-ID: <20170523091608.GA18460@rei.lan> (raw)
In-Reply-To: <24535361.19636257.1495526084444.JavaMail.zimbra@redhat.com>
Hi!
> > Hmm, strange, it looks like for 100us we got more or less all samples
> > close to 160us but for 500us half of the samples are close to 560us and
> > about 400 is more than 1000us, that does not look right. I wonder what
> > happens there. And the same for the rest of the measurements everything
> > but 100us sleeps has two peaks that are more or less 500us apart. So far
> > my machines, even VMs, had one peak and some outliners.
> >
> > Can you try to rerun the test with a realtime priority?
>
> Ran as "chrt -f 50 ./measure", results attached.
>
Looks more or less the same and I still cannot reproduce the issue on
any of the machines I have here.
Looking at errata for AMD cpus #778 says that TSC may drift under some
circumstances:
http://support.amd.com/TechDocs/51810_16h_00h-0Fh_Rev_Guide.pdf#unique_29
Can you try to disable P-state in BIOS or set cpufreq to performance?
--
Cyril Hrubis
chrubis@suse.cz
next prev parent reply other threads:[~2017-05-23 9:16 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-05-12 14:16 [LTP] [PATCH v2] [RFC] pselect01: Tune thresholds Cyril Hrubis
2017-05-15 10:03 ` Jan Stancek
2017-05-15 10:20 ` Xiao Yang
2017-05-15 13:15 ` Jan Stancek
2017-05-15 13:23 ` Cyril Hrubis
2017-05-15 12:36 ` Cyril Hrubis
2017-05-15 13:00 ` Jan Stancek
2017-05-15 13:13 ` Cyril Hrubis
2017-05-15 13:16 ` Jan Stancek
2017-05-22 8:39 ` Jan Stancek
2017-05-22 12:04 ` Cyril Hrubis
2017-05-22 13:37 ` Jan Stancek
2017-05-22 13:19 ` Cyril Hrubis
2017-05-22 14:57 ` Jan Stancek
2017-05-22 15:15 ` Cyril Hrubis
2017-05-23 7:54 ` Jan Stancek
2017-05-23 9:16 ` Cyril Hrubis [this message]
2017-05-23 9:45 ` Jan Stancek
2017-06-02 12:48 ` Jan Stancek
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