On 1/7/25 1:51 PM, Christoph Hellwig wrote: > On Tue, Jan 07, 2025 at 12:27:35PM +0530, Nilay Shroff wrote: >> As discussed in another thread with Damien, shouldn't we need to >> move bdev_can_poll() to header file? > > Well, if it was needed I would have done it, otherwise the code wouldn't > compile, would it? > I think, there won't be compile error because if we look at the show function for "io_poll" attribute under sysfs, then I see it evaluates the queue limits feature flag BLK_FEAT_POLL and returns the value. >> We also need to use this >> function while reading sysfs attribute "io-poll", no? > > This now reports polling support when the driver declared it but > later resized the number of queues to have no queues left. Which I > think is a fine tradeoff if you do that. > 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 ? Thanks, --Nilay
