On 10/6/23 01:19, Damien Le Moal wrote:
Your change seem to assume that it makes sense to be able to combine CDL with
lifetime hints. But does it really ? CDL is of dubious value for solid state
media and as far as I know, UFS world has not expressed interest. Conversely,
data lifetime hints do not make much sense for spin rust media where CDL is
important. So I would say that the combination of CDL and lifetime hints is of
dubious value.
Given this, why not simply define the 64 possible lifetime values as plain hint
values (8 to 71, following 1 to 7 for CDL) ?
The other question here if you really want to keep the bit separation approach
is: do we really need up to 64 different lifetime hints ? While the scsi
standard allows that much, does this many different lifetime make sense in
practice ? Can we ever think of a usecase that needs more than say 8 different
liftimes (3 bits) ? If you limit the number of possible lifetime hints to 8,
then we can keep 4 bits unused in the hint field for future features.
Hi Damien,
Not supporting CDL for solid state media and supporting eight different
lifetime values sounds good to me. Is this perhaps what you had in mind?
Thanks,
Bart.
--- a/include/uapi/linux/ioprio.h
+++ b/include/uapi/linux/ioprio.h
@@ -100,6 +100,14 @@ enum {
IOPRIO_HINT_DEV_DURATION_LIMIT_5 = 5,
IOPRIO_HINT_DEV_DURATION_LIMIT_6 = 6,
IOPRIO_HINT_DEV_DURATION_LIMIT_7 = 7,
+ IOPRIO_HINT_DATA_LIFE_TIME_0 = 8,
+ IOPRIO_HINT_DATA_LIFE_TIME_1 = 9,
+ IOPRIO_HINT_DATA_LIFE_TIME_2 = 10,
+ IOPRIO_HINT_DATA_LIFE_TIME_3 = 11,
+ IOPRIO_HINT_DATA_LIFE_TIME_4 = 12,
+ IOPRIO_HINT_DATA_LIFE_TIME_5 = 13,
+ IOPRIO_HINT_DATA_LIFE_TIME_6 = 14,
+ IOPRIO_HINT_DATA_LIFE_TIME_7 = 15,
};
