On Wed, Mar 26, 2025 at 09:30:51AM +0800, LongPing Wei wrote: > try_verify_in_tasklet > If verity hashes are in cache, verify data blocks in kernel tasklet > instead > - of workqueue. This option can reduce IO latency. > + of workqueue. This option can reduce IO latency. The size limits could be > + configured via /sys/module/dm_verity/parameters/use_bh_bytes. The four > + parameters correspond to limits for IOPRIO_CLASS_NONE,IOPRIO_CLASS_RT, > + IOPRIO_CLASS_BE and IOPRIO_CLASS_IDLE in turn. > + For example: > + <none>,<rt>,<be>,<idle> > + 4096,4096,4096,4096
I'm concerned about adding yet another performance tuning UAPI, which will then have to be maintained going forwards, even if the implementation changes. See e.g. how try_verify_in_tasklet has ended up not actually using tasklets anymore. Is there any strong reason for userspace needing to configure use_bh_bytes differently on different systems, vs. just having the kernel choose the best value automatically without any new UAPI surface? Keep in mind that the tunables could also be added separately later. - Eric
