Re: [fuse-devel] unusually high load

[Miklos S. <mi...@sz...>]

> > We've written a fuse-based filesystem that's used for storing millions
> > of smallish files on a storage server. The fuse filesystem is then NFS
> > mounted to dozens of machines. We're noticing that on occasion fuse will
> > chew up all the CPU time on the server, processing hundreds of thousands
> > of stat requests per second. 
> I've seen a similar issue with encfs on top of a NFS mount point (which
> is sort of the opposite order to you). The server ends up crashing with
> OOM kernel errors days to weeks later (I kid you not). i.e. I mount a
> NFS server, run up encfs on that mount point, copy tonnes of data to it,
> then stop using it. Then days to weeks later the server *always*
> crashes/hangs via a OOM error. Umounting  encfs and  then NFS after
> using it appears to stop the fault triggering.

That is weird!

Yes, NFS over FUSE does have problems, but I would have thought they
were more benign, like getting "Stale file handle" errors once in a
while.


> Google shows a few people reporting issues between fuse and NFS in
> the past?

There was a bug on SMP, that would cause CPUs to go into an infinite
loop one by one, until the whole machine completely froze.  This was
fixed in fuse-2.6.0, and actually has nothing to do with NFS other
than the fact that the NFS server seemed to trigger this better than
any other app.

Miklos