[openib-general] ib_post_recv buffer re-use

[Andrei Petrov]

On Mon, Jun 20, 2005 at 02:19:16PM -0700, Grant Grundler wrote:
> On Mon, Jun 20, 2005 at 01:06:24PM -0700, Andrei Petrov wrote:
> > Application I'm working on needs to receive and process messages
> > from RQ, so I dma_map and ib_post_recv pool of buffers. 
> > Then after I receive a message I plan to reuse already mapped
> > buffer for consequent ib_post_recv. Is that safe? Should I worry
> > about dma syncronisation?
> 
> Can you define "application" more clearly?
> Is this an in-kernel "application" or user space application?
> 

It's kernel module which uses IB verbs API as in gen2.

> Can you be more specific about the life cycles of the buffers?
> Which interfaces allocates them and which code "consumes" them?
> 

I'd say map it once, use (ib_post_recv) during entire application life,
and application allocates and consumes them internally.

> I suggest reading Documentation/DMA-API.txt in a 2.6.11 or 2.6.12
> source tree to get an idea of how DMA is managed by linux kernel.
> 

Yeah, I got my answer there, thanks. 

> grant

--Andrei