On Wed, 1 May 2013, Shawn Bohrer wrote: > Correct it doesn't and I can't prove the find command is not making > progress, however these finds normally complete in under 15 min and > we've let the stuck ones run for days. Additionally if this was just > contention I'd expect to see multiple threads/CPUs contending and I > only have a single CPU pegged running find at 99%. I should clarify > that the perf snippet above was for the entire system. Profiling just > the find command shows: > > 82.56% find [kernel.kallsyms] [k] _raw_spin_lock Couple of options to figure out what spinlock this is: use lockstat (see Documentation/lockstat.txt), which will also require a kernel rebuild, some human intervention to collect the stats, and the accompanying performance degradation, or you could try collecting /proc/$(pidof find)/stack at regular intervals and figure out which spinlock it is. > > Depending on your > > definition of "occassionally", would it be possible to run with > > CONFIG_PROVE_LOCKING and CONFIG_LOCKDEP to see if it uncovers any real > > deadlock potential? > > Yeah, I can probably enable these on a few machines and hope I get > lucky. These machines are used for real work so I'll have to gauge > what how significant the performance impact is to determine how many > machines I can sacrifice to the cause. > You'll probably only need to enable it on one machine, if a deadlock possibility exists here then lockdep will find it even without hitting it, it simply has to exercise the path that leads to it. It does have a performance degradation for that one machine, though. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>