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

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.

John

>
> Bart.
>