[PATCH v3 06/12] xprtrdma: Avoid calls to ro_unmap_safe()

Chuck Lever
2016-11-29T15:52:48Z

Micro-optimization: Most of the time, calls to ro_unmap_safe are
expensive no-ops. Call only when there is work to do.

Signed-off-by: Chuck Lever <chuck.lever-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>
---
net/sunrpc/xprtrdma/transport.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/net/sunrpc/xprtrdma/transport.c b/net/sunrpc/xprtrdma/transport.c
index ed5e285..545d3fc 100644
--- a/net/sunrpc/xprtrdma/transport.c
+++ b/net/sunrpc/xprtrdma/transport.c
@@ -621,7 +621,8 @@

dprintk("RPC: %s: called on 0x%p\n", __func__, req->rl_reply);

- ia->ri_ops->ro_unmap_safe(r_xprt, req, !RPC_IS_ASYNC(task));
+ if (unlikely(!list_empty(&req->rl_registered)))
+ ia->ri_ops->ro_unmap_safe(r_xprt, req, !RPC_IS_ASYNC(task));
rpcrdma_unmap_sges(ia, req);
rpcrdma_buffer_put(req);
}
@@ -657,7 +658,8 @@
int rc = 0;

/* On retransmit, remove any previously registered chunks */
- r_xprt->rx_ia.ri_ops->ro_unmap_safe(r_xprt, req, false);
+ if (unlikely(!list_empty(&req->rl_registered)))
+ r_xprt->rx_ia.ri_ops->ro_unmap_safe(r_xprt, req, false);

rc = rpcrdma_marshal_req(rqst);
if (rc < 0)

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