Re: [PATCH] scsi: default to scsi-mq

[John Garry]

On 11/07/2017 14:32, Bart Van Assche wrote:

On Tue, 2017-07-11 at 11:22 +0100, John Garry wrote:

On 10/07/2017 16:50, Bart Van Assche wrote:

Since a fix for the performance regression triggered by this patch will be 
upstream
soon (see also 
https://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux-block.git/commit/?h=for-linus&id=32825c45ff8f4cce937ab85b030dc693ceb1aa0a):

FYI, on linux-next 20170711 (which now includes the above patch Bart
mentioned) we see a large performance regression on hisi_sas (LLDD does
not config shost for mq).

fio read mode iops goes from ~833K (scsi_mod.use_blk_mq=n on cmdline) to
~320K

Hello John,

Thanks for the feedback. Is the kernel config with which these measurements
were performed available somewhere?

Hi Bart,

It is the default arm64 defconfig with the following changes:
CONFIG_ARM_SMMU_V3=n
CONFIG_9P_FS=n



John

We were getting a compile error in the 9p fs code, so disabled it. Turning on the IOMMU drops performance across the board for our platform, so just disabling it for the test.

Bart.

config.tar.gz
Description: application/gzip