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authorIngo Molnar <mingo@elte.hu>2008-04-25 00:25:08 +0200
committerIngo Molnar <mingo@elte.hu>2008-04-25 00:25:08 +0200
commit126e01bf92dfc5f0ba91e88be02c473e1506d7d9 (patch)
treefe883f07319193bfbec244becc43e64a22e64f95 /kernel/time
parent88a411c07b6fedcfc97b8dc51ae18540bd2beda0 (diff)
softlockup: fix NOHZ wakeup
David Miller reported: |---------------> the following commit: | commit 27ec4407790d075c325e1f4da0a19c56953cce23 | Author: Ingo Molnar <mingo@elte.hu> | Date: Thu Feb 28 21:00:21 2008 +0100 | | sched: make cpu_clock() globally synchronous | | Alexey Zaytsev reported (and bisected) that the introduction of | cpu_clock() in printk made the timestamps jump back and forth. | | Make cpu_clock() more reliable while still keeping it fast when it's | called frequently. | | Signed-off-by: Ingo Molnar <mingo@elte.hu> causes watchdog triggers when a cpu exits NOHZ state when it has been there for >= the soft lockup threshold, for example here are some messages from a 128 cpu Niagara2 box: [ 168.106406] BUG: soft lockup - CPU#11 stuck for 128s! [dd:3239] [ 168.989592] BUG: soft lockup - CPU#21 stuck for 86s! [swapper:0] [ 168.999587] BUG: soft lockup - CPU#29 stuck for 91s! [make:4511] [ 168.999615] BUG: soft lockup - CPU#2 stuck for 85s! [swapper:0] [ 169.020514] BUG: soft lockup - CPU#37 stuck for 91s! [swapper:0] [ 169.020514] BUG: soft lockup - CPU#45 stuck for 91s! [sh:4515] [ 169.020515] BUG: soft lockup - CPU#69 stuck for 92s! [swapper:0] [ 169.020515] BUG: soft lockup - CPU#77 stuck for 92s! [swapper:0] [ 169.020515] BUG: soft lockup - CPU#61 stuck for 92s! [swapper:0] [ 169.112554] BUG: soft lockup - CPU#85 stuck for 92s! [swapper:0] [ 169.112554] BUG: soft lockup - CPU#101 stuck for 92s! [swapper:0] [ 169.112554] BUG: soft lockup - CPU#109 stuck for 92s! [swapper:0] [ 169.112554] BUG: soft lockup - CPU#117 stuck for 92s! [swapper:0] [ 169.171483] BUG: soft lockup - CPU#40 stuck for 80s! [dd:3239] [ 169.331483] BUG: soft lockup - CPU#13 stuck for 86s! [swapper:0] [ 169.351500] BUG: soft lockup - CPU#43 stuck for 101s! [dd:3239] [ 169.531482] BUG: soft lockup - CPU#9 stuck for 129s! [mkdir:4565] [ 169.595754] BUG: soft lockup - CPU#20 stuck for 93s! [swapper:0] [ 169.626787] BUG: soft lockup - CPU#52 stuck for 93s! [swapper:0] [ 169.626787] BUG: soft lockup - CPU#84 stuck for 92s! [swapper:0] [ 169.636812] BUG: soft lockup - CPU#116 stuck for 94s! [swapper:0] It's simple enough to trigger this by doing a 10 minute sleep after a fresh bootup then starting a parallel kernel build. I suspect this might be reintroducing a problem we've had and fixed before, see the thread: http://marc.info/?l=linux-kernel&m=119546414004065&w=2 <---------------| touch the softlockup watchdog when exiting NOHZ state - we are obviously not locked up. Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel/time')
-rw-r--r--kernel/time/tick-sched.c1
1 files changed, 1 insertions, 0 deletions
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index d358d4e3a958..b854a895591e 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -393,6 +393,7 @@ void tick_nohz_restart_sched_tick(void)
sub_preempt_count(HARDIRQ_OFFSET);
}
+ touch_softlockup_watchdog();
/*
* Cancel the scheduled timer and restore the tick
*/