schrieb Alex Samorukov am 26.01.2012 14:52 (localtime): > Hi, > > I ported exfat fuse module to FreeBSD (PR 164473) and found that it > works much slower then on Linux. I found 2 reasons for this: >
Thanks a lot! I saw the new port :-) Hope that someone can help you improove fusefs-kmod. I remember more porters were blaming FreeBSDs fusefs support making their work hard/impossible (TrueCrypt). Hopefully some kernel hacker will read and help... Best regards, -Harry > 1) FreeBSD kernel do not allow to have nonalignment access to device > with standard read/write commands. mmap to the entire disk > (/dev/da0s1) doesn`t work also (EINVAL). > > When its not a big deal for read requests, for write it becomes a real > issue - to write non-aligned data i need to read beginning and end of > the block. So in fact for one write request i can get 2 reads. > > 2) It seems that there is a very simple read caching on such devices > without write caching at all. It makes write performance enormously > slow. I found geom_cache module, but it provides only read optimization. > > > I decided to compare speed on Linux and FreeBSD and below are my > results. I used old USB flash drive to do the tests. > > Read Speed of 100Mb: > > Linux 3.0.0: 22.7 Mb/sec > FreeBSD: 10.22 Mb/sec > FreeBSD + gcache: 18.75 Mb/sec (!) > > Write speed of 100Mb file: > Linux: 90Mb/sec (cache, much higher then device speed) > FreeBSD: 0.52 Mb/sec (!) > FreeBSD + gcache: 0.52 Mb/sec > > As you could see write performance is enormously slow. May be we need > to create some geom provider for such caching or i am missing > something? I think, that other fuse modules like ntfs-3g and fuse-ext4 > having same issue. Also i found that fuse4bsd itself is non stable and > may crash the system without any visible reasons. > _______________________________________________ > freebsd-stable@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-stable > To unsubscribe, send any mail to "freebsd-stable-unsubscr...@freebsd.org"
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