Re: [PATCH rdma-next 2/2] IB/rxe: Cache dst in QP instead of getting it for each send

[Leon Romanovsky <leon-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>]

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On Thu, Apr 20, 2017 at 12:01:14PM -0600, Jason Gunthorpe wrote:
> On Thu, Apr 20, 2017 at 08:55:56PM +0300, Leon Romanovsky wrote:
> > From: yonatanc <yonatanc-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>
> >
> > In RC QP there is no need to resolve the outgoing interface
> > for each packet, as this does not change during QP life cycle.
>
> At first blush that seems wonky, shouldn't a QP act like a TCP socket
> and be able to migrate around when things are reconfigured?

I didn't find any support for it in the code. If I don't miss anything,
the RXE will shutdown QP and create it again.

Moni, am I right?

>
> IIRC there is some kind of dst cache scheme you should use instead?

It depends on the answer to the previous question. Let's assume that I'm wrong,
so yes, dst_set_expires will be the way to go. However the code assumes
that RC QP doesn't reconfigure.

Thanks

>
> Jason

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