On Mon, Feb 27, 2023 at 06:28:41PM +0100, Hannes Reinecke wrote:

On 2/27/23 17:33, Sagi Grimberg wrote:

quoted

I'm not up to speed on how CDL is defined, but I'm unclear how CDL at
the queue level would cause the host to open more queues?

Because each CDL class would need its own submission queue in that scheme. They
can all share a single completion queue, so this scheme doesn't necassarily
increase the number of interrupt vectors.

quoted

Another question, does CDL have any relationship with NVMe "Time Limited
Error Recovery"? where the host can set a feature for timeout and
indicate if the controller should respect it per command?

While this is not a full-blown every queue/command has its own timeout,
it could address the original use-case given by Hannes. And it's already
there.

I guess that is the NVMe version of CDLs; can you give me a reference for
it?

They're not the same. TLER starts timing after a command experiences a
recoverable error, where CDL is an end-to-end timing for all commands.