On 5/16/23 06:08, Sergey Senozhatsky wrote: > 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. and that is exactly I've raised this issue, are you okay with that ? I'll send V2 with nowait enabled by default .. -ck
