[restoring CC list] On Sun, Sep 05, 2010 at 09:14:47PM +0800, Dave Chinner wrote: > On Sun, Sep 05, 2010 at 02:05:39PM +0800, Wu Fengguang wrote: > > On Sun, Sep 05, 2010 at 10:15:55AM +0800, Dave Chinner wrote: > > > On Sun, Sep 05, 2010 at 09:54:00AM +0800, Wu Fengguang wrote: > > > > Dave, could you post (publicly) the kconfig and /proc/vmstat? > > > > > > > > I'd like to check if you have swap or memory compaction enabled.. > > > > > > Swap is enabled - it has 512MB of swap space: > > > > > > $ free > > > total used free shared buffers cached > > > Mem: 4054304 100928 3953376 0 4096 43108 > > > -/+ buffers/cache: 53724 4000580 > > > Swap: 497976 0 497976 > > > > It looks swap is not used at all. > > It isn't 30s after boot, abut I haven't checked after a livelock. That's fine. I see in your fs_mark-wedge-1.png that there are no read/write IO at all when CPUs are 100% busy. So there should be no swap IO at "livelock" time. > > > And memory compaction is not enabled: > > > > > > $ grep COMPACT .config > > > # CONFIG_COMPACTION is not set Memory compaction is not likely the cause too. It will only kick in for order > 3 allocations. > > > > > > The .config is pretty much a 'make defconfig' and then enabling XFS and > > > whatever debug I need (e.g. locking, memleak, etc). > > > > Thanks! The problem seems hard to debug -- you cannot login at all > > when it is doing lock contentions, so cannot get sysrq call traces. > > Well, I don't know whether it is lock contention at all. The sets of > traces I have got previously have shown backtraces on all CPUs in > direct reclaim with several in draining queues, but no apparent lock > contention. That's interesting. Do you still have the full backtraces? Maybe your system eats too much slab cache (icache/dcache) by creating so many zero-sized files. The system may run into problems reclaiming so many (dirty) slab pages. > > How about enabling CONFIG_LOCK_STAT? Then you can check > > /proc/lock_stat when the contentions are over. > > Enabling the locking debug/stats gathering slows the workload > by a factor of 3 and doesn't produce the livelock.... Oh sorry.. but it would still be interesting to check the top contended locks for this workload without any livelocks :) Thanks, Fengguang -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>