NVME io_poll with kernel 5.x

[vrd at amazon.com]

Hi,

Since commit a4668d9ba ("nvme: default to 0 poll queues") [1], the nvme driver needs to be explicitly configured with poll_queues > 0 to allow enabling io_poll.

However, prior to poll queues separation in 4b04cc6a8 ("nvme: add separate poll queue map") [2], io_poll was enabled by default on nvme block devices. How does this work on older kernels, without dedicated poll queues?

The commit [1] says:

> We need a better way of configuring this, and given that polling is
> (still) a bit niche, let's default to using 0 poll queues.

Are there any plans / work needed for nvme to provide > 0 poll_queues by default?


[1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit?id=a4668d9ba
[2] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit?id=4b04cc6a8

Thanks,
Varad



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