[PATCH v1 02/12] xprtrdma: Raise maximum payload size to one megabyte

Chuck Lever
2015-07-09T20:41:59Z

The point of larger rsize and wsize is to reduce the per-byte cost
of memory registration and deregistration. Modern HCAs can typically
handle a megabyte or more with a single registration operation.

Signed-off-by: Chuck Lever <chuck.lever-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>
---
net/sunrpc/xprtrdma/xprt_rdma.h | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/net/sunrpc/xprtrdma/xprt_rdma.h b/net/sunrpc/xprtrdma/xprt_rdma.h
index f49dd8b..abee472 100644
--- a/net/sunrpc/xprtrdma/xprt_rdma.h
+++ b/net/sunrpc/xprtrdma/xprt_rdma.h
@@ -165,8 +165,7 @@ rdmab_to_msg(struct rpcrdma_regbuf *rb)
* struct rpcrdma_buffer. N is the max number of outstanding requests.
*/

-/* temporary static scatter/gather max */
-#define RPCRDMA_MAX_DATA_SEGS (64) /* max scatter/gather */
+#define RPCRDMA_MAX_DATA_SEGS ((1 * 1024 * 1024) / PAGE_SIZE)
#define RPCRDMA_MAX_SEGS (RPCRDMA_MAX_DATA_SEGS + 2) /* head+tail = 2 */

struct rpcrdma_buffer;