Re: scsi-mq

From: Bart Van Assche
Date: Tue Jun 17 2014 - 10:28:11 EST


On 06/12/14 15:48, Christoph Hellwig wrote:
> Bart and Robert have helped with some very detailed measurements that they
> might be able to send in reply to this, although these usually involve
> significantly reworked low level drivers to avoid other bottle necks.

In case someone would like to see the results of the measurements I ran,
these results can be found here:
https://docs.google.com/file/d/0B1YQOreL3_FxUXFMSjhmNDBNNTg.

Two important conclusions from the data in that PDF document are as follows:
- A small but significant performance improvement for the traditional
SCSI mid-layer (use_blk_mq=N).
- A very significant performance improvement for multithreaded
workloads with use_blk_mq=Y. As an example, the number of I/O
operations per second reported for the random write test increased
with 170%. That means 2.7 times the performance
of use_blk_mq=N.

I think this means the scsi-mq patches are ready for wider use.

Bart.
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