On (23/05/16 05:51), Chaitanya Kulkarni wrote: > Removed modparam v2 is ready to send, but I've few concerns enabling > nowait unconditionally for zram :- > > From brd data [1] and zram data [2] from my setup :- > > IOPs (old->new) | sys cpu% (old->new) > -------------------------------------------------- > brd | 1.5x (3919 -> 5874) | 3x (29 -> 87) > zram | 1.09x ( 29 -> 87) | 9x (11 -> 97) > > brd:- > IOPs increased by ~1.5 times (50% up) > sys CPU percentage increased by ~3.0 times (200% up) > > zram:- > IOPs increased by ~1.09 times ( 9% up) > sys CPU percentage increased by ~8.81 times (781% up) > > This comparison clearly demonstrates that zram experiences a much more > substantial CPU load relative to the increase in IOPs compared to brd. > Such a significant difference might suggest a potential CPU regression > in zram ? > > Especially for zram, if applications are not expecting this high cpu > usage then they we'll get regression reports with default nowait > approach. How about we avoid something like this with one of the > following options ? Well, zram performs decompression/compression on the CPU (per-CPU crypto streams) for each IO operation, so zram IO is CPU intensive.
