This is the mail archive of the
systemtap@sourceware.org
mailing list for the systemtap project.
[Bug runtime/3916] improve timing monotony
- From: "joshua dot i dot stone at intel dot com" <sourceware-bugzilla at sourceware dot org>
- To: systemtap at sources dot redhat dot com
- Date: 24 Jan 2007 18:52:35 -0000
- Subject: [Bug runtime/3916] improve timing monotony
- References: <20070124160955.3916.fche@redhat.com>
- Reply-to: sourceware-bugzilla at sourceware dot org
------- Additional Comments From joshua dot i dot stone at intel dot com 2007-01-24 18:52 -------
If I may link to the relevant threads...
The first report was here:
http://sourceware.org/ml/systemtap/2007-q1/msg00174.html
My reply tries to explain *why* the current implementation has this deficiency:
http://sourceware.org/ml/systemtap/2007-q1/msg00175.html
These further replies seem to confirm my hunch that the resync with kernel time
is causing the negative intervals, as the resync happens in a timer callback
(i.e. during softirq-timer).
http://sourceware.org/ml/systemtap/2007-q1/msg00183.html
http://sourceware.org/ml/systemtap/2007-q1/msg00184.html
Possible solutions:
* Find a better estimate of the cpu freq
* Use a clock that's independent of cpu freq (e.g., a motherboard/chipset timer)
* Get the kernel to provide a lockless gettimeofday
* Others?
--
http://sourceware.org/bugzilla/show_bug.cgi?id=3916
------- You are receiving this mail because: -------
You are the assignee for the bug, or are watching the assignee.