Re: [PATCH] Fix posix-cpu-timer breakage caused by stale p->last_ran value
- From: Mike Galbraith <efault@xxxxxx>
- Date: Thu, 22 Feb 2007 10:16:18 +0100
On Thu, 2007-02-22 at 01:33 +0100, Thomas Gleixner wrote:
Problem description at:
http://bugzilla.kernel.org/show_bug.cgi?id=8048
Commit b18ec80396834497933d77b81ec0918519f4e2a7
[PATCH] sched: improve migration accuracy
optimized the scheduler time calculations, but broke posix-cpu-timers.
The problem is that the p->last_ran value is not updated after a context
switch. So a subsequent call to current_sched_time() calculates with a
stale p->last_ran value, i.e. accounts the full time, which the task was
scheduled away.
Oops, missed that. You could also remove the prev->last_ran assignment
just above your addition, and turn this into a negative cost bugfix :)
-Mike
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- From: Thomas Gleixner
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