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| author | Chuck Lever | 2015-08-03 19:04:08 +0200 |
|---|---|---|
| committer | Anna Schumaker | 2015-08-05 22:21:27 +0200 |
| commit | 33943b2974734ca5e5bef583d09ddd1eded6a77b (patch) | |
| tree | 4804d4d7db18d2e746bde066691c47981ecd1d0a /net/sunrpc/xprtrdma/rpc_rdma.c | |
| parent | xprtrdma: Always provide a write list when sending NFS READ (diff) | |
| download | kernel-qcow2-linux-33943b2974734ca5e5bef583d09ddd1eded6a77b.tar.gz kernel-qcow2-linux-33943b2974734ca5e5bef583d09ddd1eded6a77b.tar.xz kernel-qcow2-linux-33943b2974734ca5e5bef583d09ddd1eded6a77b.zip | |
xprtrdma: Don't provide a reply chunk when expecting a short reply
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 <chuck.lever@oracle.com>
Reviewed-by: Sagi Grimberg <sagig@mellanox.com>
Tested-by: Devesh Sharma <devesh.sharma@avagotech.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Diffstat (limited to 'net/sunrpc/xprtrdma/rpc_rdma.c')
| -rw-r--r-- | net/sunrpc/xprtrdma/rpc_rdma.c | 13 |
1 files changed, 1 insertions, 12 deletions
diff --git a/net/sunrpc/xprtrdma/rpc_rdma.c b/net/sunrpc/xprtrdma/rpc_rdma.c index e7cf976aff47..62150ae2dc09 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) { |