Currently Linux always offers a reply chunk, even when the reply can be sent inline (ie. is smaller than 1KB).
On the client, registering a memory region can be expensive. A server may choose not to use the reply chunk, wasting the cost of the registration. This is a change only for RPC replies smaller than 1KB which the server constructs in the RPC reply send buffer. Because the elements of the reply must be XDR encoded, a copy-free data transfer has no benefit in this case. Signed-off-by: Chuck Lever <[email protected]> Reviewed-by: Sagi Grimberg <[email protected]> Tested-by: Devesh Sharma <[email protected]> --- net/sunrpc/xprtrdma/rpc_rdma.c | 13 +------------ 1 file changed, 1 insertion(+), 12 deletions(-) diff --git a/net/sunrpc/xprtrdma/rpc_rdma.c b/net/sunrpc/xprtrdma/rpc_rdma.c index e7cf976..62150ae 100644 --- a/net/sunrpc/xprtrdma/rpc_rdma.c +++ b/net/sunrpc/xprtrdma/rpc_rdma.c @@ -420,7 +420,7 @@ rpcrdma_marshal_req(struct rpc_rqst *rqst) * * o Read ops return data as write chunk(s), header as inline. * o If the expected result is under the inline threshold, all ops - * return as inline (but see later). + * return as inline. * o Large non-read ops return as a single reply chunk. */ if (rqst->rq_rcv_buf.flags & XDRBUF_READ) @@ -476,17 +476,6 @@ rpcrdma_marshal_req(struct rpc_rqst *rqst) headerp->rm_body.rm_nochunks.rm_empty[2] = xdr_zero; /* new length after pullup */ rpclen = rqst->rq_svec[0].iov_len; - /* Currently we try to not actually use read inline. - * Reply chunks have the desirable property that - * they land, packed, directly in the target buffers - * without headers, so they require no fixup. The - * additional RDMA Write op sends the same amount - * of data, streams on-the-wire and adds no overhead - * on receive. Therefore, we request a reply chunk - * for non-writes wherever feasible and efficient. - */ - if (wtype == rpcrdma_noch) - wtype = rpcrdma_replych; } if (rtype != rpcrdma_noch) { -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
