On Sat, Jul 27, 2013 at 04:26:28AM -0700, Paul E. McKenney wrote: > On Sat, Jul 27, 2013 at 04:21:01PM +1000, Dave Chinner wrote: > > On Fri, Jul 26, 2013 at 09:05:24PM -0700, Paul E. McKenney wrote: > > > Could you please send your patches over to Dave Jones right now? I am > > > getting quite tired of getting RCU CPU stall warning complaints from > > > him that turn out to be due to highly contended sync() system calls. > > > > Then ignore them until the code is ready - it'll be 3.12 before the > > fixes are merged, anyway, because the lock contention fix requires > > infrastructure that is currently in mmotm that is queued for 3.12 > > (i.e. the per-node list infrastructure) to fix a whole bunch of > > other, more critical VFS lock contention problems. Seeing as a new > > mmotm went out last week, I should have the patches ready for review > > early next week. > > > > FWIW, we (as in XFS filesystem testers) regularly run tests that > > have hundreds of concurrent sys_sync() calls running at the same > > time. e.g. xfstests::xfs/297 runs a 1000 fsstress processes while > > freezing and unfreezing the filesystem, and that usually shows > > hundreds of threads running sys_sync concurrently after a short > > amount of runtime. So it's pretty clear that what Dave is seeing > > is not necessarily representative of what happens when there ar lots > > of sys_sync() calls run concurrently. > > So Dave might be finding an additional problem. ;-) Dave will always find problems. If you want something broken, give it to Dave and he'll hand it back in pieces. :) > > BTW, concurrent syncfs() calls are going to have exactly the same > > problem as concurrent sync() calls, as is any other operation that > > results in a walk of the per-superblock inodes list. > > Yep! Your upcoming patch addresses these as well? Yes, it does. Cheers, Dave. -- Dave Chinner david@xxxxxxxxxxxxx -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
