Messages in this thread | | | Date | Mon, 07 Jul 2008 14:16:49 -0400 | From | Steven Rostedt <> | Subject | [PATCH 0/3] sched_clock updates |
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Working with ftrace on linux-tip, I found a few problems with the sched_clock code that is suppose to help an unstable TSC keep accurate time. The problem I was seeing was on a box with a stable TSC. The time would jump around a lot. One would think that code to help unstable TSC keep time would not be a problem with a stable TSC.
The main change was the patch that handled the dynamic ticks. That was the culprit of bein off by several jiffies.
With these patches applied, ftrace is quite a bit better with respect to time. But there is still jumps that happen that do not happen with sched_clock.
I'm suspecting that the problems that still exist have more to do with time updates or a drift between the TSC and the clock used for GTOD.
Anyway, enjoy,
-- Steve
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