rbd striping format v1 / v2 benchmark

rbd striping format v1 / v2 benchmark

[Stefan Priebe]

Hello list,

i've done some benchmarks regarding striping / v1 / v2.

Results:
format 1:

   write: io=5739MB, bw=65278KB/s, iops=16319, runt= 90029msec
   read : io=5771MB, bw=65636KB/s, iops=16408, runt= 90030msec
   write: io=77224MB, bw=874044KB/s, iops=213, runt= 90473msec
   read : io=178840MB, bw=1983MB/s, iops=495, runt= 90168msec

format 2:

  --stripe-count 8 --stripe-unit 524288 -s 4194304

   write: io=5377MB, bw=61147KB/s, iops=15286, runt= 90041msec
   read : io=5332MB, bw=60617KB/s, iops=15154, runt= 90067msec
   write: io=75136MB, bw=849285KB/s, iops=207, runt= 90593msec
   read : io=160292MB, bw=1777MB/s, iops=444, runt= 90226msec

  --stripe-count 4 --stripe-unit 1048576 -s 4194304

   write: io=5301MB, bw=60281KB/s, iops=15070, runt= 90046msec
   read : io=5367MB, bw=61031KB/s, iops=15257, runt= 90057msec
   write: io=74448MB, bw=840293KB/s, iops=205, runt= 90724msec
   read : io=170616MB, bw=1891MB/s, iops=472, runt= 90227msec

So it seems right now that striping doesn't improve performance.

Greets,
Stefan

Re: rbd striping format v1 / v2 benchmark

[Sage Weil]

On Wed, 7 Nov 2012, Stefan Priebe wrote:
> Hello list,
> 
> i've done some benchmarks regarding striping / v1 / v2.
> 
> Results:
> format 1:
> 
>   write: io=5739MB, bw=65278KB/s, iops=16319, runt= 90029msec
>   read : io=5771MB, bw=65636KB/s, iops=16408, runt= 90030msec
>   write: io=77224MB, bw=874044KB/s, iops=213, runt= 90473msec
>   read : io=178840MB, bw=1983MB/s, iops=495, runt= 90168msec
> 
> format 2:
> 
>  --stripe-count 8 --stripe-unit 524288 -s 4194304
> 
>   write: io=5377MB, bw=61147KB/s, iops=15286, runt= 90041msec
>   read : io=5332MB, bw=60617KB/s, iops=15154, runt= 90067msec
>   write: io=75136MB, bw=849285KB/s, iops=207, runt= 90593msec
>   read : io=160292MB, bw=1777MB/s, iops=444, runt= 90226msec
> 
>  --stripe-count 4 --stripe-unit 1048576 -s 4194304
> 
>   write: io=5301MB, bw=60281KB/s, iops=15070, runt= 90046msec
>   read : io=5367MB, bw=61031KB/s, iops=15257, runt= 90057msec
>   write: io=74448MB, bw=840293KB/s, iops=205, runt= 90724msec
>   read : io=170616MB, bw=1891MB/s, iops=472, runt= 90227msec
> 
> So it seems right now that striping doesn't improve performance.

It's mainly going to help when you have a deep queue of small sequential 
IOs, and the fact that they are all piling up on a single rbd block is 
turning into a bottleneck.  The rest of the time the overhead of splitting 
things into smaller pieces will slow you down.

The intended use case is a database journal or something similar, where 
the latency requirements prevent us from making larger IOs, but things are 
still sequential.

	rbd bench-write ...

will generate this workload.

sage

> 
> Greets,
> Stefan
> --
> To unsubscribe from this list: send the line "unsubscribe ceph-devel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> 
>