From mboxrd@z Thu Jan  1 00:00:00 1970
From: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Subject: Re: [PATCH] scsi: default to scsi-mq
Date: Wed, 12 Jul 2017 23:54:01 +0800
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To: Bart Van Assche <Bart.VanAssche@wdc.com>
Cc: "hch@lst.de" <hch@lst.de>, "linux-scsi@vger.kernel.org" <linux-scsi@vger.kernel.org>, "john.garry@huawei.com" <john.garry@huawei.com>, "linuxarm@huawei.com" <linuxarm@huawei.com>

On Wed, 12 Jul 2017 14:18:14 +0000
Bart Van Assche <Bart.VanAssche@wdc.com> wrote:

> On Wed, 2017-07-12 at 09:26 +0100, John Garry wrote:
> > > > What block driver controls the block device for which the performance
> > > > regression
> > > > has been observed? How many hardware queues were created by that block
> > > > driver
> > > > (see also /sys/block/*/mq/...)?  
> > 
> > Just confirming that we have only 1 queue:
> > /sys/block/sdc/mq/0 as example  
> 
> Hello John,
> 
> Can you also check the I/O scheduler that has been selected?
> 
> Thanks,
> 
> Bart.
Hi Bart,

Original numbers were with deadline-mq (not deliberately specified - so the
default for this setup)  To flesh them out a bit I've
run the equivalent test with all the options on today's linux next.

iodepth=2048, 4k blocks read only 6 disks 6 processes.

SMMU disabled for now due to ongoing work to reduce it's impact.

none : 716k IOPS
mq-deadline : 305k IOPS
kyber: 321k IOPS

noop, scsi_mq disable using the kernel commandline option: 937k IOPS

Thanks,

Jonathan