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From: Gleb Natapov (glebn_at_[hidden])
Date: 2007-06-14 06:37:28


On Wed, Jun 13, 2007 at 07:08:51PM +0300, Gleb Natapov wrote:
> On Wed, Jun 13, 2007 at 09:38:21AM -0600, Galen Shipman wrote:
> > Hi Gleb,
> >
> > As we have discussed before I am working on adding support for
> > multiple QPs with either per peer resources or shared resources.
> > As a result of this I am trying to clean up a lot of the OpenIB code.
> > It has grown up organically over the years and needs some attention.
> > Perhaps we can coordinate on commits or even work from the same temp
> > branch to do an overall cleanup as well as addressing the issue you
> > describe in this email.
> >
> > I bring this up because this commit will conflict quite a bit with
> > what I am working on, I can always merge it by hand but it may make
> > sense for us to get this all done in one area and then bring it all
> > over?
>
> I am not committing this yet. I want people to review my logic and the
> patch. If the change is OK with everyone how cares then I want this
> change to go into 1.2 branch.
>
> I don't care how this change will get to the trunk. I can use patched
> version for a while. If you branch is in working state right now I can
> merge this change into it tomorrow.

The patch applies to ib_multifrag as is without a conflict. But the branch
doesn't compile with or without the patch so I was not able to test it.
Do you have some uncommitted changes that may generate a conflict? Can
you commit them so they can be resolved? If there is no conflict between
your work and this patch may be it is a good idea to commit it to your
branch and trunk for testing?

>
> >
> > Thanks,
> >
> > Galen
> >
> >
> > On Jun 13, 2007, at 7:27 AM, Gleb Natapov wrote:
> >
> > > Hello everyone,
> > >
> > > I encountered a problem with openib on depend connection code.
> > > Basically
> > > it works only by pure luck if you have more then one endpoint for
> > > the same
> > > proc and sometimes breaks in mysterious ways.
> > >
> > > The algo works like this: A wants to connect to B so it creates QP
> > > and sends it
> > > to B. B receives the QP from A and looks for endpoint that is not
> > > yet associated
> > > with remote endpoint, creates QP for it and sends info back. Now A
> > > receives
> > > the QP and goes through the same logic as B i.e looks for endpoint
> > > that is not
> > > yet connected, BUT there is no guaranty that it will find the
> > > endpoint that
> > > initiated the connection in the first place! And if it finds
> > > another one it will
> > > create QP for it and will send it back to B and so on and so forth.
> > > In the end
> > > I sometimes receive a peculiar mesh of connection where no QP has a
> > > connection
> > > back to it from the peer process.
> > >
> > > To overcome this problem B needs to send back some info that will
> > > allow A to
> > > determine the endpoint that initiated a connection request. The
> > > lid:qp pair
> > > will allow for this. But even then the problem will remain if two
> > > procs initiate
> > > connection at the same time. To dial with simultaneous connection
> > > asymmetry
> > > protocol have to be used one peer became master another slave.
> > > Slave alway
> > > initiate a connection to master. Master choose local endpoint to
> > > satisfy
> > > incoming request and sends info back to a slave. If master wants to
> > > initiate a
> > > connection it send message to a slave and slave initiate connection
> > > back to
> > > master.
> > >
> > > Included patch implements an algorithm described above and work for
> > > all
> > > scenarios for which current code fails to create a connection.
> > >
> > > --
> > > Gleb.
> > > <fix_openib_wireup.diff>
> > > _______________________________________________
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> > > devel_at_[hidden]
> > > http://www.open-mpi.org/mailman/listinfo.cgi/devel
> >
> > _______________________________________________
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>
> --
> Gleb.
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--
			Gleb.