Re: [PATCH v8 00/18] blk-mq/scsi: Provide hostwide shared tags for SCSI HBAs

[John Garry]

On 03/09/2020 22:23, Jens Axboe wrote:
> On 8/19/20 9:20 AM, John Garry wrote:
> > Hi all,
> >
> > Here is v8 of the patchset.
> >
> > In this version of the series, we keep the shared sbitmap for driver tags,
> > and introduce changes to fix up the tag budgeting across request queues.
> > We also have a change to count requests per-hctx for when an elevator is
> > enabled, as an optimisation. I also dropped the debugfs changes - more on
> > that below.
> >
> > Some performance figures:
> >
> > Using 12x SAS SSDs on hisi_sas v3 hw. mq-deadline results are included,
> > but it is not always an appropriate scheduler to use.
> >
> > Tag depth 		4000 (default)			260**
> >
> > Baseline (v5.9-rc1):
> > none sched:		2094K IOPS			513K
> > mq-deadline sched:	2145K IOPS			1336K
> >
> > Final, host_tagset=0 in LLDD *, ***:
> > none sched:		2120K IOPS			550K
> > mq-deadline sched:	2121K IOPS			1309K
> >
> > Final ***:
> > none sched:		2132K IOPS			1185			
> > mq-deadline sched:	2145K IOPS			2097	
> >
> > * this is relevant as this is the performance in supporting but not
> >    enabling the feature
> > ** depth=260 is relevant as some point where we are regularly waiting for
> >     tags to be available. Figures were are a bit unstable here.
> > *** Included "[PATCH V4] scsi: core: only re-run queue in
> >      scsi_end_request() if device queue is busy"
> >
> > A copy of the patches can be found here:
> > https://github.com/hisilicon/kernel-dev/tree/private-topic-blk-mq-shared-tags-v8
> >
> > The hpsa patch depends on:
> > https://lore.kernel.org/linux-scsi/20200430131904.5847-1-hare@xxxxxxx/
> >
> > And the smartpqi patch is not to be accepted.
> >
> > Comments (and testing) welcome, thanks!
>
> I applied 1-11, leaving the SCSI core bits and drivers to Martin. I can
> also carry them, just let me know.

Great, thanks!

So the SCSI parts depend on the block parts for building, so I guess it 
makes sense if you could carry them also.

hpsa and smartpqi patches are pending for now, but the rest could be 
picked up. Martin/James may want more review of the SCSI core bits, though.

Thanks again,
John