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Subject: Re: [OMPI devel] [PATCH] openib: clean-up connect to allow for new cm's
From: Pavel Shamis (Pasha) (pasha_at_[hidden])
Date: 2007-12-12 09:08:31


Gleb Natapov wrote:
> On Wed, Dec 12, 2007 at 03:37:26PM +0200, Pavel Shamis (Pasha) wrote:
>
>> Gleb Natapov wrote:
>>
>>> On Tue, Dec 11, 2007 at 08:16:07PM -0500, Jeff Squyres wrote:
>>>
>>>
>>>> Isn't there a better way somehow? Perhaps we should have "select"
>>>> call *all* the functions and accept back a priority. The one with the
>>>> highest priority then wins. This is quite similar to much of the
>>>> other selection logic in OMPI.
>>>>
>>>> Sidenote: Keep in mind that there are some changes coming to select
>>>> CPCs on a per-endpoint basis (I can't look up the trac ticket right
>>>> now...). This makes things a little complicated -- do we need
>>>> btl_openib_cpc_include and btl_openib_cpc_exclude MCA params to
>>>> include/exclude CPCs (because you might need more than one CPC in a
>>>> single job)? That wouldn't be hard to do.
>>>>
>>>> But then what to do about if someone sets to use some XRC QPs and
>>>> selects to use OOB or RDMA CM? How do we catch this and print an
>>>> error? It doesn't seem right to put the "if num_xrc_qps>0" check in
>>>> every CPC. What happens if you try to make an XRC QP when not using
>>>> xoob? Where is the error detected and what kind of error message do
>>>> we print?
>>>>
>>>>
>>>>
>>> In my opinion "X" notation for QP specification should be removed. I
>>> didn't want this to prevent XRC merging so I haven't raced this point.
>>> It is enough to have two types of QPs "P" - SW credit management "S" -
>>> HW credit management.
>>>
>> How will you decide witch QP type to use ? (SRQ or XRC)
>>
>>
> If both sides support XOOB and priority of XOOB is higher then all other CPC
> then create XRC, otherwise use regular RC.
>
If some body have connectX hca but he want to use SRQ and not XRC ?
I guess anyway we will be need some additional parameter that will allow
enable/disable XRC, correct ? (So why just not leave the X qp type ?)