2011/5/12 Lev Serebryakov <l...@serebryakov.spb.ru>: > Hello, Mdf. > You wrote 12 мая 2011 г., 15:40:25: > >>>> Does FreeBSD have some custom call, which can be used where Linux >>>> programs uses posix_fadvice() and DARWIN ones fcntl(F_RDADVISE)? >>>> >>>> It is like madvise(2) but for file descriptors. >>> No, it does not (and I think the function is spelled posix_fadvise()). >>> >>> mdf reserved the syscall slot for posix_fadvise in his recent work >>> on posix_fallocate(). Might be, he could comment more. >> Whoops, I replied bot forgot to reply-all. > >> Adding a stub for posix_fadvise() is on my list of things to do, since >> we use it at $WORK in our custom filesystem, but the list is long and >> spare time is short. > >> Nominally a technically correct implementation can do error checking >> and then nothing. Even after a stub is added to the OS, each >> filesystem must implement a VOP to do the work. > transmission Torrents client rely on this syscall. It could be beuilt > without it, of course (it is in our ports!), but it seems, that it > produce much more sane disk load on Linux, because uses pre-fetch via > posix_fadvise(). My profiling shows that pread() could take about 40% > of it CPU time (8 seconds out of 20 with turned on ktrace, for > example), even if throughput is very modest (700KiB/s, for example). > Authors say, that they didn't observe such behavior on Linux (which > has posix_fadvise()) or MacOS X (with fcntl(F_RDADVISE))... > > May be, we should go to fs@ with this thread now?
Probably; the interface and a few unit tests are a start but the common filesystems (presumably ufs and zfs and perhaps others) will need support and I do not have any knowledge of the internals of those filesystems. Cheers, matthew _______________________________________________ freebsd-hackers@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-hackers To unsubscribe, send any mail to "freebsd-hackers-unsubscr...@freebsd.org"
