Messages in this thread | | | Date | Mon, 29 Jul 2013 17:06:43 +1000 | From | Dave Chinner <> | Subject | Re: [PATCH RFC fs] v2 Make sync() satisfy many requests with one invocation |
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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@fromorbit.com
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