Re: Updated performance results

[Steven Pratt <slpratt@austin.ibm.com>]

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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