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authorIngo Molnar <mingo@elte.hu>2008-04-14 02:50:02 -0400
committerIngo Molnar <mingo@elte.hu>2008-07-31 11:20:29 -0400
commite4e4e534faa3c2be4e165ce414f44b76ada7208c (patch)
tree615280ce53bdba4f99c95616d2a1527c3b863c39 /kernel/time
parent39675e89fb472c1b9c8e740e00acb1df2bbc6be7 (diff)
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 825b4c00fe44..f5da526424a9 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)
289 ts->tick_stopped = 1; 289 ts->tick_stopped = 1;
290 ts->idle_jiffies = last_jiffies; 290 ts->idle_jiffies = last_jiffies;
291 rcu_enter_nohz(); 291 rcu_enter_nohz();
292 sched_clock_tick_stop(cpu);
293 } 292 }
294 293
295 /* 294 /*
@@ -392,7 +391,6 @@ void tick_nohz_restart_sched_tick(void)
392 select_nohz_load_balancer(0); 391 select_nohz_load_balancer(0);
393 now = ktime_get(); 392 now = ktime_get();
394 tick_do_update_jiffies64(now); 393 tick_do_update_jiffies64(now);
395 sched_clock_tick_start(cpu);
396 cpu_clear(cpu, nohz_cpu_mask); 394 cpu_clear(cpu, nohz_cpu_mask);
397 395
398 /* 396 /*