Re: [PATCH v3 01/18] block: introduce duration-limits priority class

Bart Van Assche
2023-01-24T20:36:31Z

On 1/24/23 11:27, Bart Van Assche wrote:
> Implementing duration limit support using the I/O priority mechanism
> makes it impossible to configure the I/O priority for commands that have
> a duration limit. Shouldn't the duration limit be independent of the I/O
> priority? Am I perhaps missing something?

(replying to my own e-mail)

In SAM-6 I found the following: "The device server may use the duration
expiration time to determine the order of processing commands with
the SIMPLE task attribute within the task set. A difference in duration
expiration time between commands may override other scheduling
considerations (e.g., different times to access different logical block
addresses or vendor specific scheduling considerations). Processing of a
collection of commands with different command duration limit settings
should cause a command with an earlier duration expiration time to
complete with status sooner than a command with a later duration
expiration time."

Do I understand correctly that it is optional for a SCSI device to
interpret the command duration as a priority and that this is not mandatory?

Thanks,

Bart.