[Pvfs2-developers] disabling ncache

[Phil Carns]

I doubt that this is the problem, but I should mention that I although 
the main ncache patch was accepted, we are still missing the sys-rename 
update in trunk (I just noticed Friday).  It is the second of the two 
patches mentioned in this thread:

http://www.beowulf-underground.org/pipermail/pvfs2-developers/2006-August/002390.html

I am attaching it to this email just in case.  I seriously doubt that 
the mpi program is using rename but we may as well get this in there :)

If the ncache really needs to be disabled I don't really have a 
preference.  Probably the env variable is the easiest.

-Phil

Murali Vilayannur wrote:
> 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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>>
>>
> 
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