On 5/9/18 11:21 AM, Theodore Y. Ts'o wrote: > On Wed, May 09, 2018 at 08:23:00AM -0600, Jens Axboe wrote: >> Streams is essentially the only thing ki_hint is currently used for, >> with the write life time hints mapping to a stream. The idea for the >> user side API was to have other things than just write life time hints. >> >> Since Adam wants to do priorities, he'd either need to pack into the >> existing ki_hint, or do this patch does, which is make it smaller and >> add a new member. I think the latter is cleaner. > > Fair enough; but maybe we can use a u8 instead of a u16? 65,535 > priorities still seem like way more than would ever make sense. I > think 256 priorities is still way to many, but it's simpler while > still reserving number of bits for future se.
The intention was to mimic the ioprio_set system call, which uses 3 bits for a prio class and 13 bits for a prio_value. IDK what is the right amount of bits to use, but the existing use of bits seemed flexible enough to support many types of applications and devices. > > - Ted >
