On Tue, Aug 03, 2010 at 05:01:52AM -0400, Christoph Hellwig wrote: > On Mon, Aug 02, 2010 at 05:09:39PM -0700, Darrick J. Wong wrote: > > Well... on my fsync-happy workloads, this seems to cut the barrier count down > > by about 20%, and speeds it up by about 20%. > > Care to share the test case for this? I'd be especially interesting on > how it behaves with non-draining barriers / cache flushes in fsync. Sure. When I run blktrace with the ffsb profile, I get these results: barriers transactions/sec 16212 206 15625 201 10442 269 10870 266 15658 201 Without Jan's patch: barriers transactions/sec 20855 177 20963 177 20340 174 20908 177 The two ~270 results are a little odd... if we ignore them, the net gain with Jan's patch is about a 25% reduction in barriers issued and about a 15% increase in tps. (If we don't, it's ~30% and ~30%, respectively.) That said, I was running mkfs between runs, so it's possible that the disk layout could have shifted a bit. If I turn off the fsync parts of the ffsb profile, the barrier counts drop to about a couple every second or so, which means that Jan's patch doesn't have much of an effect. But it does help if someone is hammering on the filesystem with fsync. The ffsb profile is attached below. --D ----------- time=300 alignio=1 directio=1 [filesystem0] location=/mnt/ num_files=100000 num_dirs=1000 reuse=1 # File sizes range from 1kB to 1MB. size_weight 1KB 10 size_weight 2KB 15 size_weight 4KB 16 size_weight 8KB 16 size_weight 16KB 15 size_weight 32KB 10 size_weight 64KB 8 size_weight 128KB 4 size_weight 256KB 3 size_weight 512KB 2 size_weight 1MB 1 create_blocksize=1048576 [end0] [threadgroup0] num_threads=64 readall_weight=4 create_fsync_weight=2 delete_weight=1 append_weight = 1 append_fsync_weight = 1 stat_weight = 1 create_weight = 1 writeall_weight = 1 writeall_fsync_weight = 1 open_close_weight = 1 write_size=64KB write_blocksize=512KB read_size=64KB read_blocksize=512KB [stats] enable_stats=1 enable_range=1 msec_range 0.00 0.01 msec_range 0.01 0.02 msec_range 0.02 0.05 msec_range 0.05 0.10 msec_range 0.10 0.20 msec_range 0.20 0.50 msec_range 0.50 1.00 msec_range 1.00 2.00 msec_range 2.00 5.00 msec_range 5.00 10.00 msec_range 10.00 20.00 msec_range 20.00 50.00 msec_range 50.00 100.00 msec_range 100.00 200.00 msec_range 200.00 500.00 msec_range 500.00 1000.00 msec_range 1000.00 2000.00 msec_range 2000.00 5000.00 msec_range 5000.00 10000.00 [end] [end0] -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
