Hello Eric, Tuesday, September 27, 2016, 6:17:22 AM, you wrote: > Add support to bcache hinting functions and sysfs to hint by the ioprio of > 'current' which can be configured with `ionice`. > Cache hinting is configurable by writing 'class,level' pairs to sysfs. > These are the defaults: > echo 2,7 > /sys/block/bcache0/bcache/ioprio_bypass > echo 2,0 > /sys/block/bcache0/bcache/ioprio_writeback > (-p) IO Class (-n) Class level Action > ----------------------------------------------------- > (1) Realtime 0-7 Writeback > (2) Best-effort 0 Writeback > (2) Best-effort 1-6 Original bcache logic > (2) Best-effort 7 Bypass cache > (3) Idle n/a Bypass cache Not sure it's a good idea, at all. If I set cache policy to, say, write-through, then I expect write-back to never happen, regardless of what userspace does with IO priority. Similarly, using low IO priority (idle or best effort-7) should not make IO *slow regardless of any other IO load* (which would happen if cache is completely bypassed). Right now, it looks to me as inappropriate mixing of different concepts. Unless I fail to understand something. Pavel Goran -- To unsubscribe from this list: send the line "unsubscribe linux-bcache" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
