Jens Axboe <jens.axboe@xxxxxxxxxx> writes: >> > We can easily make F_GETPIPE_SZ return bytes, but I don't think passing >> > in bytes to F_SETPIPE_SZ makes a lot of sense. The pipe array must be a >> > power of 2 in pages. So the question is if that makes the API cleaner, >> > passing in number of pages but returning bytes? Or pass in bytes all >> > around, but have F_SETPIPE_SZ round to the nearest multiple of pow2 in >> > pages if need be. Then it would return a size at least what was passed >> > in, or error. I really think "power of 2 in pages" is simply current implementation detail, not detail of pipe API. >> 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)? Thanks. -- OGAWA Hirofumi <hirofumi@xxxxxxxxxxxxxxxxxx> -- 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
