[Pvfs2-developers] disabling ncache

[Murali Vilayannur]

Hey Rob,
Shall we first try to diagnose the problem a little bit?
Can you describe the problem a little bit more?
Thanks,
Murali

> Hey gang
>
> One of the ROMIO tests (noncontig_coll2) started failing around the
> time we comitted the revamped ncache.  If I disable the ncache by
> setting NCACHE_DEFAULT_TIMEOUT_MSECS to zero, the test passes again.
>
> Sam and I have a couple solutions, but none of them are satsifying
> given we need to coordinate any API changes with ROMIO:
>
> - To compliment PVFS2_SET_DEBUGMASK, add a PVFS2_NCACHE_TIMEOUT
>   environment variable (this one might be the winner)
>
> - Add a new routine to the pvfs2 API that modifies the ncache timeout
>   values.  This would impose a ROMIO pre-req on
>   pvfs2-1.whatever-is-next.
>
> - ignore the problem.  It only shows up if one set of processes
>   open/write/read/close a file, it is deleted, and a different set (or
>   same set but different order) open/write/read/close the file.  Most
>   places that care to set ROMIO's cb_config_list hint aren't going
>   to change it when they delete and re-create a file.
>
> I think I'm going to go with the environment variable solution, since
> if ROMIO happens to link against an older PVFS2, nothing bad will
> happen (as long as they don't go crazy with cb_config_list).   Does
> anybody else have any suggestions?
>
> ==rob
>
> --
> Rob Latham
> Mathematics and Computer Science Division    A215 0178 EA2D B059 8CDF
> Argonne National Labs, IL USA                B29D F333 664A 4280 315B
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