The patch titled
Fix posix-cpu-timer breakage caused by stale p->last_ran value
has been added to the -mm tree. Its filename is
fix-posix-cpu-timer-breakage-caused-by-stale-p-last_ran.patch
*** Remember to use Documentation/SubmitChecklist when testing your code ***
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: Fix posix-cpu-timer breakage caused by stale p->last_ran value
From: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
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.
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/sched.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff -puN kernel/sched.c~fix-posix-cpu-timer-breakage-caused-by-stale-p-last_ran kernel/sched.c
--- a/kernel/sched.c~fix-posix-cpu-timer-breakage-caused-by-stale-p-last_ran
+++ a/kernel/sched.c
@@ -3566,7 +3566,7 @@ switch_tasks:
sched_info_switch(prev, next);
if (likely(prev != next)) {
- next->timestamp = now;
+ next->timestamp = next->last_ran = now;
rq->nr_switches++;
rq->curr = next;
++*switch_count;
_
Patches currently in -mm which might be from tglx@xxxxxxxxxxxxx are
fix-posix-cpu-timer-breakage-caused-by-stale-p-last_ran.patch
git-block.patch
sched-fix-idle-load-balancing-in-softirqd-context.patch
sched-dynticks-idle-load-balancing-v2.patch
scheduled-removal-of-sa_xxx-interrupt-flags-fixups-3.patch
-
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