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authorIngo Molnar <mingo@elte.hu>2008-04-14 08:50:02 +0200
committerIngo Molnar <mingo@elte.hu>2008-07-31 17:20:29 +0200
commite4e4e534faa3c2be4e165ce414f44b76ada7208c (patch)
tree615280ce53bdba4f99c95616d2a1527c3b863c39 /kernel/time
parent39675e89fb472c1b9c8e740e00acb1df2bbc6be7 (diff)
downloadop-kernel-dev-e4e4e534faa3c2be4e165ce414f44b76ada7208c.zip
op-kernel-dev-e4e4e534faa3c2be4e165ce414f44b76ada7208c.tar.gz
sched clock: revert various sched_clock() changes
Found an interactivity problem on a quad core test-system - simple CPU loops would occasionally delay the system un an unacceptable way. After much debugging with Peter Zijlstra it turned out that the problem is caused by the string of sched_clock() changes - they caused the CPU clock to jump backwards a bit - which confuses the scheduler arithmetics. (which is unsigned for performance reasons) So revert: # c300ba2: sched_clock: and multiplier for TSC to gtod drift # c0c8773: sched_clock: only update deltas with local reads. # af52a90: sched_clock: stop maximum check on NO HZ # f7cce27: sched_clock: widen the max and min time This solves the interactivity problems. Signed-off-by: Ingo Molnar <mingo@elte.hu> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Acked-by: Mike Galbraith <efault@gmx.de>
Diffstat (limited to 'kernel/time')
-rw-r--r--kernel/time/tick-sched.c2
1 files changed, 0 insertions, 2 deletions
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index 825b4c0..f5da526 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -289,7 +289,6 @@ void tick_nohz_stop_sched_tick(int inidle)
ts->tick_stopped = 1;
ts->idle_jiffies = last_jiffies;
rcu_enter_nohz();
- sched_clock_tick_stop(cpu);
}
/*
@@ -392,7 +391,6 @@ void tick_nohz_restart_sched_tick(void)
select_nohz_load_balancer(0);
now = ktime_get();
tick_do_update_jiffies64(now);
- sched_clock_tick_start(cpu);
cpu_clear(cpu, nohz_cpu_mask);
/*
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