linux-kernel - [PATCH 0/3] sched

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Date:	Mon, 07 Jul 2008 14:16:49 -0400
From:	Steven Rostedt <rostedt@...dmis.org>
To:	Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...e.hu>,
	Thomas Gleixner <tglx@...utronix.de>,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org
Subject: [PATCH 0/3] sched_clock updates

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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