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.
Send instant messages to your online friends http://au.messenger.yahoo.com 

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>