[ewg] APM Example

[Abhinav Vishnu]

Hi Roland,

On 4/26/07, Roland Dreier <rdreier at cisco.com> wrote:
>
>     Abhinav> However, VAPI has an event which specifies the successful
>     Abhinav> transition of MIGRATED -> ARMED (I know very well, that
>     Abhinav> it is done through modify_qp). But just the success of
>     Abhinav> modify_qp does not explicitly tell the time at which the
>     Abhinav> transition successfully occured, does it?
>
> You don't know the time that the transition occurred, except that it
> is between when you called modify QP and when it returned.  But an
> asynchronous event doesn't really help, does it?


It does help. APM is not only defined for network fault tolerance, it can
also be used for load-balancing. With this event, one can know when
the path is loaded and it is safe to call modify_qp.

Also, do you have any script which can potentially bring a port down
from Active state, without actually unplugging the cable? Please let
me know.

Thanks,

:- Abhinav


All an event would
> tell you is that the transition occurred some time before the event was
> generated, which is some time before when the event was delivered to you.
>
>     Abhinav> Specifically:
>
>     Abhinav> VAPI_PATH_MIG_ARMED would make my day. I believe that
>     Abhinav> VAPI_QP_PATH_MIGRATED is similar to
>     Abhinav> IB_EVENT_PATH_MIG. Please correct me if i am wrong.
>
> I see... VAPI_PATH_MIG_ARMED is a new event that was added only in
> VAPI 4.1.0, which was why I didn't know about it.  Only Mellanox HCAs
> support it, it is not specified by the InfiniBand architecture, and I
> don't really see the point of it (as I tried to explain above).
>
> - R.
>



-- 
Abhinav Vishnu
Graduate Student
Computer Science and Engineering
The Ohio State University
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