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From: Gleb Natapov (glebn_at_[hidden])
Date: 2005-10-19 10:18:41


On Wed, Oct 19, 2005 at 09:05:41AM -0600, Galen Mark Shipman wrote:
> We changed things a bit in the mpool, the deregister will remove the
> registration from the cache and then call release, if the reference count
> is <=0, the memory is then deregistered, otherwise it will be deregistered
> later via another release call. The BTL module increments the reference
> count on the registration so it should not be deregestered until the the
> registration's reference count is decremented in btl_free.
>
> Are you seeing an actual vapi error with the attached code? If so it is
> probably a reference count issue that we need to deal with.
I see error with openib btl. I haven't check mvapi. I see that openib
deregister and mvapi deregister implemented differently. Does openib lag
behind mvapi?

>
> Thanks,
>
> Galen
>
> > Hello Galen,
> >
> > It seams this issue is still present and can be easily triggered.
> > (see attached program). Do you have plans to fix it?
> >
> > On Wed, Sep 21, 2005 at 12:06:18PM -0600, Galen M. Shipman wrote:
> >> Gleb,
> >>
> >> >
> >> > Gleb Natapov wrote:
> >> >
> >> >> Hello Galen,
> >> >>
> >> >> Finally I've got some time to look through the new code.
> >> >> I have couple of notes. In pml_ob1_rdma.c you try to merge
> >> >> registrations in the number of places. The code looks like this:
> >> >> btl_mpool->mpool_deregister(btl_mpool, reg);
> >> >> btl_mpool->mpool_register(btl_mpool,
> >> >> new_base,
> >> >> new_len,
> >> >> MCA_MPOOL_FLAGS_CACHE,
> >> >> &reg);
> >> >> How do you know reg is not in use? You can't deregister it if
> >> >> somebody
> >> >> is using the registration!
> >> >>
> >> >
> >> > Good catch... this should check the reference count and
> >> > only deregister when the reference count actually goes to zero...
> >> > _______________________________________________
> >> > devel mailing list
> >> > devel_at_[hidden]
> >> > http://www.open-mpi.org/mailman/listinfo.cgi/devel
> >> >
> >>
> >> Yes, this was a good catch.. This was causing all sorts of fun for us!
> >> Thanks,
> >>
> >
> > --
> > Gleb.
> >

--
			Gleb.