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authorChuck Lever <chuck.lever@oracle.com>2017-02-08 17:00:18 -0500
committerAnna Schumaker <Anna.Schumaker@Netapp.com>2017-02-10 14:02:36 -0500
commitc6f5b47f9fdeef12c0896e5af4bb3416c97d91c4 (patch)
treef280dc7d027d1bfecf54428c2b13528ffd5266c4 /net/sunrpc
parent16f906d66cd76fb9895cbc628f447532a7ac1faa (diff)
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xprtrdma: Shrink send SGEs array
We no longer need to accommodate an xdr_buf whose pages start at an offset and cross extra page boundaries. If there are more partial or whole pages to send than there are available SGEs, the marshaling logic is now smart enough to use a Read chunk instead of failing. Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Diffstat (limited to 'net/sunrpc')
-rw-r--r--net/sunrpc/xprtrdma/xprt_rdma.h11
1 files changed, 7 insertions, 4 deletions
diff --git a/net/sunrpc/xprtrdma/xprt_rdma.h b/net/sunrpc/xprtrdma/xprt_rdma.h
index 3d7e9c9bad1f..852dd0a750a5 100644
--- a/net/sunrpc/xprtrdma/xprt_rdma.h
+++ b/net/sunrpc/xprtrdma/xprt_rdma.h
@@ -305,16 +305,19 @@ struct rpcrdma_mr_seg { /* chunk descriptors */
char *mr_offset; /* kva if no page, else offset */
};
-/* Reserve enough Send SGEs to send a maximum size inline request:
+/* The Send SGE array is provisioned to send a maximum size
+ * inline request:
* - RPC-over-RDMA header
* - xdr_buf head iovec
- * - RPCRDMA_MAX_INLINE bytes, possibly unaligned, in pages
+ * - RPCRDMA_MAX_INLINE bytes, in pages
* - xdr_buf tail iovec
+ *
+ * The actual number of array elements consumed by each RPC
+ * depends on the device's max_sge limit.
*/
enum {
RPCRDMA_MIN_SEND_SGES = 3,
- RPCRDMA_MAX_SEND_PAGES = PAGE_SIZE + RPCRDMA_MAX_INLINE - 1,
- RPCRDMA_MAX_PAGE_SGES = (RPCRDMA_MAX_SEND_PAGES >> PAGE_SHIFT) + 1,
+ RPCRDMA_MAX_PAGE_SGES = RPCRDMA_MAX_INLINE >> PAGE_SHIFT,
RPCRDMA_MAX_SEND_SGES = 1 + 1 + RPCRDMA_MAX_PAGE_SGES + 1,
};