[Pvfs2-developers] ncache causes shared creat problems

[Robert Latham]

On Mon, Aug 28, 2006 at 08:37:16PM +0200, Phil Carns wrote:
> There really isn't much way around this with the local ncache
> approach.  Maybe the stock release should have the ncache disabled
> if this workload will be common (having one client delete a
> particular file and then a different client immediately recreate a
> file with the same name), or maybe at least disable it by default
> for system interface usage since MPI programs are probably more
> likely to trigger this than VFS programs.

Yeah, I've taken the approach in CVS of having ROMIO disable the
ncache unless the PVFS2_NCACHE_TIMEOUT environment variable is set.
It's overkill, but we could create PVFS2 files on different clients if
open is called with COMM_SELF.   

There aren't too many typical mpi-io workloads that benefit from the
ncache (right?), and the environment variable lets us easily
experiment.

==rob

-- 
Rob Latham
Mathematics and Computer Science Division    A215 0178 EA2D B059 8CDF
Argonne National Labs, IL USA                B29D F333 664A 4280 315B