At 12:40 PM 8/25/2006, Sean Hefty wrote: >> Thomas> How does an adapter guarantee that no bridges or other >> Thomas> intervening devices reorder their writes, or for that >> Thomas> matter flush them to memory at all!? >> >>That's a good point. The HCA would have to do a read to flush the >>posted writes, and I'm sure it's not doing that (since it would add >>horrible latency for no good reason). >> >>I guess it's not safe to rely on ordering of RDMA writes after all. > >Couldn't the same point then be made that a CQ entry may come before the data >has been posted?
When the CQ entry arrives, the context that polls it off the queue must use the dma_sync_*() api to finalize any associated data transactions (known by the uper layer). This is basic, and it's the reason that a completion is so important. The completion, in and of itself, isn't what drives the synchronization. It's the transfer of control to the processor. Tom. _______________________________________________ openib-general mailing list openib-general@openib.org http://openib.org/mailman/listinfo/openib-general To unsubscribe, please visit http://openib.org/mailman/listinfo/openib-general
