From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Philip Frey1 Sent: Wednesday, August 13, 2008 1:24 AM To: Steve Wise Cc: [email protected] Subject: Re: [ofa-general] cxgb3: MW Support > Philip Frey1 wrote: > > > > Are memory windows supported by the Chelsio T3 adapter? If so, what is > > the verb to bind/unbind them? > > > > MWs are supported in ofed-1.4, which is about the beta. The support in > linux/ofed is only for kernel-mode MWs. > > Are you doing user mode or kernel mode? User mode :) > For kernel mode, you allocate a mw with ib_alloc_mw(). And you bind it > with ib_bind_mw(). You can invalidate it by posting a IB_WR_LOCAL_INV > work request to the send queue. Then you can do a subsequent bind. > Deallocate with ib_dealloc_mw(). Ok, thanks. I will keep that in mind for later use (as soon as it is available). > For user mode, I have a patch series that adds support for MWs, but I > hasn't been submitted yet for group review. Its on my (very long) todo > list. :) No worries, it is not urgent. I was just wondering how expensive it is to allocate a memory window as opposed to allocating a memory region - way cheaper I guess. [felix] Yes. Note that QP operations are considered 'fast path' (and are fully pipelined in T3) with respect to memory/STag management they include - Fast Register Non Shared MR (priv QP only) - Bind MW - Local Invalidate STag You can issue e.g. a Bind MW and then immediately use the MW STag in e.g. a following RDMA Write. Ordering guarantees that MW is ready by the time the RDMA Write is executed. Thanks, Philip
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