Re: [PATCH v1 09/12] xprtrdma: Prepare rpcrdma_ep_post() for RDMA_NOMSG calls

Jason Gunthorpe
2015-07-10T22:44:02Z

On Fri, Jul 10, 2015 at 10:53:40AM -0400, Chuck Lever wrote:

> It is certainly possible to examine the device’s max_sge field
> in rpcrdma_ep_create() and fail transport creation if the
> device’s max_sge is less than RPC_MAX_IOVS.

I just want to draw Sagi's attention to this problem, when considering
my thoughts on an alternate API for posting.

This thread is about NFS needing 4 sges for a (rare?) message type.

The API direction I suggested addresses this kind of issue as well,
because under the covers the driver/core can spin up a temporary MR
for this case and thus support an infinite s/g list for all posts.

Jason