]> Sylvain Le Gall <sylvain@le-gall.net> writes: > On 29-10-2009, Goswin von Brederlow <goswin-v-b@web.de> wrote: >> Xavier Leroy <Xavier.Leroy@inria.fr> writes: >>> Goswin von Brederlow wrote: >> >> Here are some benchmark results: >> >> get an int out of a string: >> C Ocaml >> uint8 le 19.496 17.433 >> int8 le 19.298 17.850 >> uint16 le 19.427 25.046 >> int16 le 19.383 27.664 >> uint16 be 20.502 23.200 >> int16 be 20.350 27.535 >> >> get an int out of a Bigarray.Array1.t: >> safe unsafe >> uint8 le 55.194s 54.508s >> uint64 le 80.51s 81.46s >> > > Can you provide us with the corresponding code and benchmark? > > Maybe you can just commit this in libaio/test/bench.ml. > > Regards, > Sylvain Le Gall As Christophe guessed the problem was polymorphic functions. If I specify a fixed Array1 type then the compiler uses the optimized access functions. Makes unsafe Bigarray slightly faster than unsafe string actually (must not optimize int_of_char/Char.unsafe_chr away) and that independent of argument size (on set, on get allocating int32/int64 costs time so they are slower). So Bigarray is the fastest but getting different types out of a Bigarray will be tricky. Unaligned even more so if not impossible. I have to sleep on this. Maybe in my use case I can have all structures int64 aligned and then split the int64 up in ocaml where structures have smaller members. Would have been too much to have a Bigarray with access functions for any type. Maybe some little wrapper with Obj.Magic will do *hide*. As for libaio it should be easy to make it create and use any Bigarray type. MfG Goswin