Messages in this thread | | | Date | Sat, 13 Jan 2007 15:39:45 +1100 | From | Nick Piggin <> | Subject | Re: High lock spin time for zone->lru_lock under extreme conditions |
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Ravikiran G Thirumalai wrote: > Hi, > We noticed high interrupt hold off times while running some memory intensive > tests on a Sun x4600 8 socket 16 core x86_64 box. We noticed softlockups,
[...]
> We did not use any lock debugging options and used plain old rdtsc to > measure cycles. (We disable cpu freq scaling in the BIOS). All we did was > this: > > void __lockfunc _spin_lock_irq(spinlock_t *lock) > { > local_irq_disable(); > ------------------------> rdtsc(t1); > preempt_disable(); > spin_acquire(&lock->dep_map, 0, 0, _RET_IP_); > _raw_spin_lock(lock); > ------------------------> rdtsc(t2); > if (lock->spin_time < (t2 - t1)) > lock->spin_time = t2 - t1; > } > > On some runs, we found that the zone->lru_lock spun for 33 seconds or more > while the maximal CS time was 3 seconds or so.
What is the "CS time"?
It would be interesting to know how long the maximal lru_lock *hold* time is, which could give us a better indication of whether it is a hardware problem.
For example, if the maximum hold time is 10ms, that it might indicate a hardware fairness problem.
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