On Tue, Oct 03, 2023 at 10:26:27AM -0700, Bart Van Assche wrote: > On 10/2/23 18:40, Martin K. Petersen wrote: > > > > Niklas, > > > > > I don't know which user facing API Martin's I/O hinting series is > > > intending to use. > > > > I'm just using ioprio. > > Hi Martin, > > Do you plan to use existing bits from the ioprio bitmask or new bits? Bits > 0-2 are used for the priority level. Bits 3-5 are used for CDL. Bits 13-15 > are used for the I/O priority. The SCSI and NVMe standard define 64 > different data lifetimes (six bits). So there are 16 - 3 - 3 - 6 = 4 > remaining bits. Hello Bart, I think the math is: 16 - 3 (prio level) - 3 (CDL) - 3 (prio class) = 7 so if we want 64 different values for data lifetimes (we previously only had 4 different values), that is 6 bits: 16 - 3 (prio level) - 3 (CDL) - 3 (prio class) - 6 (lifetime) = 1 so only one bit left for Martin :) Not very much room to play with... Kind regards, Niklas
