[rds-devel] [ofa-general] [PATCH RFC] rds: add iwarp support

[Richard Frank]

This all seems to be a bit restrictive - which will require some changes in 
how Oracle uses the IPC for rdma operations - but we need to start somewhere 
so this seems reasonable.

If we can get bcopy running with Oracle - that'd be a great goal for 1.4. If 
it's going to require changes in Oracle to use IWARP RDMA - then we're 
talking about a later Orace release to use it...

I'm out on vacation will be back in two weeks..

Rick

----- Original Message ----- 
From: "Olaf Kirch" <olaf.kirch at oracle.com>
To: "Or Gerlitz" <ogerlitz at voltaire.com>
Cc: <rds-devel at oss.oracle.com>; <general at lists.openfabrics.org>
Sent: Tuesday, July 08, 2008 8:00 AM
Subject: Re: [rds-devel] [ofa-general] [PATCH RFC] rds: add iwarp support


> On Tuesday 08 July 2008 12:11:40 Or Gerlitz wrote:
>> Olaf Kirch wrote:
>> > Okay, there's a third way to fix this, which may even work with today's 
>> > Oracle IPC code. The hack is to not submit the fastreg WR until we post 
>> > a SEND that transmits the rkey to a peer. Then
>> >
>> >  - we have a QP to post the WRs to
>> >  - we post the fastreg and the SEND to the same QP,
>> > ensuring that the peer doesn't initiate the RDMA
>> > before we've set up the memory registration.
>> Yes, as Steve noted, using the same QP for the fastreg and send that
>> carries the rkey/stag is a must since the send should be fenced on the
>> fastreg completion to make sure the remote side uses a valid key.
>
> One theoretical problem is what happens if the application wants to
> register a memory range and send the rkey to two peers at the same time?
> We would have to stall the second send explicitly as long as we
> haven't seen the completion for the first send.
>
> Olaf
> -- 
> Olaf Kirch  |  --- o --- Nous sommes du soleil we love when we play
> okir at lst.de |    / | \   sol.dhoop.naytheet.ah kin.ir.samse.qurax
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