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Subject: Re: [PATCH RFC v7 10/12] megaraid_sas: switch fusion adapters to MQ
To:     Kashyap Desai <kashyap.desai@broadcom.com>,
        Ming Lei <ming.lei@redhat.com>
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On 10/08/2020 17:38, Kashyap Desai wrote:
> 
> Functional Test -
> 
> I cover overnight IO testing using <fio> script which sends 4K rand read,
> read, rand write and write IOs to the 24 SAS JBOD drives.
> Some of the JBOD has ioscheduler=none and some of the JBOD has
> ioscheduler=mq-deadline
> I used additional script which change sdev->queue_depth of each device
> from 2 to 16 range at the interval of 5 seconds.
> I used additional script which toggle "rq_affinity=1" and "rq_affinity=2"
> at the interval of 5 seconds.
> 
> I did not noticed any IO hang.
> 
> Thanks, Kashyap
> 

Nice work. I think v8 series can now be prepared, since this final 
performance issue reported looks resolved. But I still don't know what's 
going on for "[PATCHv6 00/21] scsi: enable reserved commands for LLDDs", 
which current hpsa patch relies on for basic functionality :(

>>
>>  From 06993ddf5c5dbe0e772cc38342919eb61a57bc50 Mon Sep 17 00:00:00
>> 2001
>> From: Ming Lei<ming.lei@redhat.com>
>> Date: Wed, 5 Aug 2020 16:35:53 +0800
>> Subject: [PATCH] scsi: core: only re-run queue in scsi_end_request() if
> device
>> queue is busy

Ming, I assume that you will send this directly to SCSI maintainers when 
the merge window closes.

>>
>> Now the request queue is run in scsi_end_request() unconditionally if
> both
>> target queue and host queue is ready. We should have re-run request
> queue
>> only after this device queue becomes busy for restarting this LUN only.
>>
>> Recently Long Li reported that cost of run queue may be very heavy in
> case of
>> high queue depth. So improve this situation by only running the request
> queue
>> when this LUN is busy.