(Illustration by Gaich Muramatsu)
Hi Greg, On Mon, Aug 04, 2014 at 08:48:01PM -0400, Greg Troxel wrote: > >> Moving to FUSE would be a much better approach if you want to get rid of > >> kernel complexity. Patches are welcome. > > > > That would be more portable, sure, but I expect that we'd lose performance. > > I appreciate that the current implementation offers very high efficiency > > for read()/write()/seek(). > > Well, it's very efficient on Linux and NetBSD, and it has zero > efficiency on many other platforms!! That's right and I fully support the idea of (someone else than myself) implementing a FUSE kernel interface. Nevertheless there is hardly any point in dropping the existing and well performing Coda-specific implementation, where it exists and is present in the mainstream kernel. > But seriously, in 2010+ all other serious distributed filesystems except > NFS seem to be "FUSE first". A particular case in point is GlusterFS. > Someone in NetBSD has been getting Gluster ported to NetBSD, and has > reported file read rates over the network (GbE) from remote servers at a > substantial fraction (60%? more?) of the GbE rate, on a > normal-but-fairly-high-end amd64 box. > > So I don't think the performance issues are really that big a deal any > more. The performance of read/write in Coda (note we are not talking about open() and friends) does not relate to the ability to "fill" the network. It is about processes efficiently accessing the _local_ (cached) files. So your comparison may be not exactly applicable. (I recall ZFS on Linux has remarkably worse performance via FUSE compared to natively) Nevertheless what I actually wrote about was the need to replace the pioctl interface. AFAICT FUSE does not provide any replacement. For Coda to be portable kernel-wise we must anyway do pioctl via a different channel, a local socket or probably better via the upcall interface. If I correctly interpret comments in the code there was/is even an intention to do so. (Jan please correct me if I am totally off the road on this point) Regards, RuneReceived on 2014-08-05 03:27:41