On Tue, Jun 08, 2010 at 03:59:07PM -0400, Christoph Hellwig wrote: > > We already rely on the fact that the sync code will cause a synchronous > log force later on (currently via xfs_fs_sync_fs -> xfs_quiesce_data -> > xfs_sync_data), so no need to do this here. This allows us to avoid > a lot of synchronous log forces during sync, which pays of especially > with delayed logging enabled. Some compilebench numbers that show > this: > > xfs (delayed logging, 256k logbufs) > =================================== > > intial create 25.94 MB/s 25.75 MB/s 25.64 MB/s > create 8.54 MB/s 9.12 MB/s 9.15 MB/s > patch 2.47 MB/s 2.47 MB/s 3.17 MB/s > compile 29.65 MB/s 30.51 MB/s 27.33 MB/s > clean 90.92 MB/s 98.83 MB/s 128.87 MB/s > read tree 11.90 MB/s 11.84 MB/s 8.56 MB/s > read compiled 28.75 MB/s 29.96 MB/s 24.25 MB/s > delete tree 8.39 seconds 8.12 seconds 8.46 seconds > delete compiled 8.35 seconds 8.44 seconds 5.11 seconds > stat tree 6.03 seconds 5.59 seconds 5.19 seconds > stat compiled tree 9.00 seconds 9.52 seconds 8.49 seconds > > > xfs + write_inode log_force removal > =================================== > intial create 25.87 MB/s 25.76 MB/s 25.87 MB/s > create 15.18 MB/s 14.80 MB/s 14.94 MB/s > patch 3.13 MB/s 3.14 MB/s 3.11 MB/s > compile 36.74 MB/s 37.17 MB/s 36.84 MB/s > clean 226.02 MB/s 222.58 MB/s 217.94 MB/s > read tree 15.14 MB/s 15.02 MB/s 15.14 MB/s > read compiled tree 29.30 MB/s 29.31 MB/s 29.32 MB/s > delete tree 6.22 seconds 6.14 seconds 6.15 seconds > delete compiled tree 5.75 seconds 5.92 seconds 5.81 seconds > stat tree 4.60 seconds 4.51 seconds 4.56 seconds > stat compiled tree 4.07 seconds 3.87 seconds 3.96 seconds > > Signed-off-by: Christoph Hellwig <hch@xxxxxx> All great - I attempted this myself - but it breaks bulkstat. See xfstest 183: 183 2s ... - output mismatch (see 183.out.bad) --- 183.out 2010-04-28 15:00:22.000000000 +1000 +++ 183.out.bad 2010-06-09 17:10:23.000000000 +1000 @@ -1,4 +1,4 @@ QA output created by 183 Start original bulkstat_unlink_test with -r switch Runing extended checks. -Iteration 0 ... (100 files)passed +Iteration 0 ... (100 files)ERROR, count(2) != scount(1). Ran: 183 Failures: 183 Failed 1 of 1 tests Test 183 fails with this patch because it leaves the inode pinned in the WB_SYNC_ALL case after calling xfs_log_inode(), and so the inode can't be flushed to the backing buffer. Hence bulkstat may not see changes to an inode after a sync becuase they weren't flushed during the sync. I think that we need to revisit bulkstat's use of the backing buffers for performance reasons now we have a much more scalable inode cache. Having to keep the backing buffers coherent is only going to be more problematic in future as things get even more asynchronous.... Cheers, Dave. -- Dave Chinner david@xxxxxxxxxxxxx _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
