[PATCH 0/3] Add BLK_MQ_F_NO_SCHED flag to admin tag set

[Israel Rukshin]

On 10/18/2017 5:31 PM, Sagi Grimberg wrote:
>
>>>> Since commit b86dd81
>>>> "block: get rid of blk-mq default scheduler choice Kconfig entries",
>>>> when setting nr_hw_queues to 1 the admin tag set uses mq-deadline 
>>>> scheduler.
>>>> This flag is useful for admin queues that aren't used for normal IO.
>>>> We already use this flag at nvme-pci.
>>>
>>> How is the fact that we set a single hw queue has anything to do with
>>> the admin tagset?
>>
>> Setting nr_hw_queues attribute of admin tag set to 1 influence the value
>> of nr_hw_queues attribute of the admin queue.
>> At /block/elevator.c
>> elevator_init() selects the scheduler according to the value of 
>> nr_hw_queues
>> attribute of the admin queue.
>
> Oh, I confused your meaning with setting nr_hw_queues to 1 in the IO
> tagset makes a difference for the admin tagset.

No,
I just wanted to say that before commit b86dd8 there was no scheduler 
for the admin q.
After commit b86dd8 I saw that mq-deadline scheduler was selected for 
the admin q.