On 11/01/18 18:43, Konstantin Khlebnikov wrote:
With default 8ms idle slice BFQ is up to 10 times slower than CFQ
for massive random read workloads for common SATA SSD.
For now zero idle slice gives better out of box experience.
CFQ employs this since commit 41c0126b3f22 ("block: Make CFQ default
to IOPS mode on SSDs")
Well, that's interesting because 3 years ago I made the same suggestion
and was told that BFQ's heuristics automagically make it not idle when
rotational=0. Did you actually benchmark this? I just tried and don't
get a noticeable performance difference with slice_idle=0 compared to
deadline.
Discussion link:
https://groups.google.com/forum/#!msg/bfq-iosched/iRMw2n3kYLY/6l9cIm3TBgAJ
curious..
Holger
