From: Per Oberg <pero@wolfram.com>
To: xenomai <xenomai@xenomai.org>
Subject: clocksource 'tsc' marked unstable, CLOCK_HOST_REALTIME went bananas
Date: Thu, 28 Mar 2019 03:47:45 -0500 (CDT) [thread overview]
Message-ID: <76739224.1358458.1553762865210.JavaMail.zimbra@wolfram.com> (raw)
Hello list!
I am running Xenomai 3.0.7. released version with Kernel 4.9.90 patchlevel 6.
We have a new x86-64 hardware, and during a test-run the clocksource went unstable, see (1) below for dmesg.
After this, calls to "clock_gettime(CLOCK_HOST_REALTIME,&timeStamp)" went bananas. Like if time stopped completely, (or possibly jumped back in time at least a few hours). Stuff running on timers (using CLOCK_MONOTONIC)kept running fine. I tried switching time to hpet using "clocksource=hpet" but this didn't work at all. Either time (CLOCK_HOST_REALTIME) jumped back and forth or it completely stopped. Now I'm using "tsc=reliable" and haven't seen any issues since.
I think I know why tsc may be deemed unreliable, but why can't I run using hpet?
What are the drawbacks for xenomai with using tsc=reliable ?
----------------- (1) -----------------
[19139.502750] clocksource: timekeeping watchdog on CPU3: Marking clocksource 'tsc' as unstable because the skew is too large:
[19139.503499] clocksource: 'hpet' wd_now: f347622d wd_last: 35ab9afb mask: ffffffff
[19139.504245] clocksource: 'tsc' cs_now: 31567c07fb36 cs_last: 30ffd3d5ec2d mask: ffffffffffffffff
[19139.505045] clocksource: Switched to clocksource hpet
----------------- (1) -----------------
Best regards
Per Öberg
next reply other threads:[~2019-03-28 8:47 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-28 8:47 Per Oberg [this message]
2019-04-02 11:05 ` clocksource 'tsc' marked unstable, CLOCK_HOST_REALTIME went bananas Jan Kiszka
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