Chris Mason wrote:
On Mon, Aug 31, 2009 at 12:49:13PM -0500, Steven Pratt wrote:
Better late than never. Finally got this finished up. Mixed bag on
this one. BTRFS lags significantly on single threaded. Seems
unable to keep IO outstanding to the device. Less that 60% busy on
the DM device, compared to 97%+ for all other filesystems.
nodatacow helps out, increasing utilization to about 70%, but still
trails by a large margin.
Hi Steve,
Jens Axboe did some profiling on his big test rig and I think we found
the biggest CPU problems. The end result is now setting in the master
branch of the btrfs-unstable repo.
On his boxes, btrfs went from around 400MB/s streaming writes to 1GB/s
limit, and we're now tied with XFS while using less CPU time.
Hopefully you will see similar results ;)
Hmmm, well no I didn't. Throughputs at 1 and 128 threads are pretty
much unchanged, although I do see a good CPU savings on the 128 thread
case (with cow). For 16 threads we actually regressed with cow enabled.
Results are here:
http://btrfs.boxacle.net/repository/raid/large_create_test/write-test/1M_odirect_create.html
I'll try to look more into this next week.
Steve
-chris
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