Daniel Rosenberg <drosen@xxxxxxxxxx> writes: > On Tue, Feb 11, 2020 at 7:38 PM Eric Biggers <ebiggers@xxxxxxxxxx> wrote: >> >> Indirect function calls are expensive these days for various reasons, including >> Spectre mitigations and CFI. Are you sure it's okay from a performance >> perspective to make an indirect call for every byte of the pathname? >> >> > +typedef int (*utf8_itr_actor_t)(struct utf8_itr_context *, int byte, int pos); >> >> The byte argument probably should be 'u8', to avoid confusion about whether it's >> a byte or a Unicode codepoint. >> just for the record, we use int utf8byte because it can fail error codes, but that is not the case here. It should be u8. > > Gabriel, what do you think here? I could change it to either exposing > the things necessary to do the hashing in libfs, or instead of the > general purpose iterator, just have a hash function inside of unicode > that will compute the hash given a seed value. Sorry for the delay, I'm away on a long vacation and intentionally staying away from my laptop :) Eric has a very good point, if not prohibitively, it is unnecessarily expensive for a hot path. Why not expose utf8ncursor and utf8byte to libfs and implement the hash in libfs? -- Gabriel Krisman Bertazi
