Re: [PATCH RFC v7 00/12] blk-mq/scsi: Provide hostwide shared tags for SCSI HBAs

John Garry
2020-06-11T09:36:26Z

On 11/06/2020 04:07, Ming Lei wrote:
>> 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:
>> none sched: 2290K IOPS 894K
>> mq-deadline sched: 2341K IOPS 2313K
>>
>> Final, host_tagset=0 in LLDD*
>> none sched: 2289K IOPS 703K
>> mq-deadline sched: 2337K IOPS 2291K
>>
>> Final:
>> none sched: 2281K IOPS 1101K
>> mq-deadline sched: 2322K IOPS 1278K
>>
>> * 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 for testing.
>>
>> A copy of the patches can be found here:
>> https://github.com/hisilicon/kernel-dev/commits/private-topic-blk-mq-shared-tags-rfc-v7
>>
>> And to progress this series, we the the following to go in first, when ready:
>> https://lore.kernel.org/linux-scsi/20200430131904.5847-1-hare@suse.de/
> I'd suggest to add options to enable shared tags for null_blk & scsi_debug in V8, so
> that it is easier to verify the changes without real hardware.
>

ok, fine, I can look at including that. To stop the series getting too
large, I might spin off the early patches, which are not strictly related.

Thanks,
John