On Monday 06 April 2020 09:37:38 Kohada.Tetsuhiro@xxxxxxxxxxxxxxxxxxxxxxxxxxx wrote: > > > If you want to get an unbiased hash value by specifying an 8 or 16-bit > > > value, > > > > Hello! In exfat we have sequence of 21-bit values (not 8, not 16). > > hash_32() generates a less-biased hash, even for 21-bit characters. > > The hash of partial_name_hash() for the filename with the following character is ... > - 21-bit(surrogate pair): the upper 3-bits of hash tend to be 0. > - 16-bit(mostly CJKV): the upper 8-bits of hash tend to be 0. > - 8-bit(mostly latin): the upper 16-bits of hash tend to be 0. > > I think the more frequently used latin/CJKV characters are more important > when considering the hash efficiency of surrogate pair characters. > > The hash of partial_name_hash() for 8/16-bit characters is also biased. > However, it works well. > > Surrogate pair characters are used less frequently, and the hash of > partial_name_hash() has less bias than for 8/16 bit characters. > > So I think there is no problem with your patch. So partial_name_hash() like I used it in this patch series is enough?
