On 1/14/24 21:59, Christoph Hellwig wrote:
How can the driver make any sensible decision here? This really looks
like a horrible band aid.
(just returned from a four day trip)
Hi Christoph,
I agree that in general it is not up to the driver to decide whether or
not fair tag sharing should be disabled. The UFS driver is an exception
because we know that for all UFS use cases the latency for all logical
units is similar.
You'll need to figure out a way to make the fair sharing less costly
or adaptic. That might involve making it a little less fair, which
is probably ok as long a the original goals are met.
I disagree. Fair tag sharing is something that should be implemented in
hardware (e.g. in an NVMe controller) rather than in software.
Additionally, I'm convinced that it is impossible to come up with a
better algorithm than the current without slowing down the hot path in
the block layer, something that nobody wants.
Bart.
