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.
--
SUSE Labs, Novell Inc.
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