Re: [PATCH 3/8] block: don't update BLK_FEAT_POLL in __blk_mq_update_nr_hw_queues

Nilay Shroff
2025-01-07T17:55:32Z

On 1/7/25 7:21 PM, Christoph Hellwig wrote:
> On Tue, Jan 07, 2025 at 02:53:40PM +0530, Nilay Shroff wrote:
>> When I applied you patch on my system and access io_poll attribute
>> of one of my nvme disk, I see it returns 1, though I didn't configure
>> poll queue for the disk. With this patch, as we're now always setting
>> BLK_FEAT_POLL (under blk_mq_alloc_queue()) it return 1. So when I haven't
>> configured poll queue for NVMe driver, shouldn't it return 0 when I access
>> /sys/block/nvmeXnY/queue/io_poll ?
>
> While that was the case with the previous RFC series it should not be
> the case with this version, as the nvme driver does not enable the
> poll tag set map unless poll queues are enabled. I also double checked
> that I do not see it on any of my test setups.
>
Ohk I did install previous RFC series and tested it.
On another note, with latest patch series, assuming NVMe driver reports polling
support when it's loaded, accessing io_poll under sysfs reports 1. This is good.
However later resizing queue so that no poll queue is left and I reset the controller
and then access the io_poll it still reports 1. Is this expected? Other than this
everything else looks fine.

Thanks,
--Nilay