On Mon, May 24 2010, OGAWA Hirofumi wrote: > Jens Axboe <jens.axboe@xxxxxxxxxx> writes: > > >> >> I'd recommend this: Pass it in and out in bytes. Don't round to a > >> >> power of 2. Require the user to know what they are doing. Give an > >> >> error if the user doesn't supply a power-of-2 * page-size for > >> >> F_SETPIPE_SZ. (Again, consider the case of architectures with > >> >> switchable page sizes.) > >> > > >> > But is there much point in erroring on an incorrect size? If the > >> > application says "I need at least 120kb of space in there", kernel > >> > returns "OK, you got 128kb". Would returning -1/EINVAL for that case > >> > really make a better API? Doesn't seem like it to me. > >> > >> FWIW, my first impression of this was setsockopt(SO_RCV/SNDBUF) of unix > >> socket. Well, API itself wouldn't say "at least this size" or "exactly > >> this size", so, in here, important thing is consistency of interfaces, I > >> think. (And the both is sane API at least for me if those had > >> consistency in the system.) > >> > >> Well, so how about set/get in bytes, and kernel will set "at least > >> specified size" actually like setsockopt(SO_RCV/SNDBUF)? > > > > Isn't that pretty much what I described? > > Yes, probably. Well, 120kb was still multiple of page size. :) It is, but 120KB/page_size is not (which is the power-of-2 of interest here). -- Jens Axboe -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
