From: Steve Wise <swise@opengridcomputing.com>
Date: Thu, 9 Apr 2009 14:09:36 +0000 (+0000)
Subject: RDS/IW+IB: Set recv ring low water mark to 1/2 full.
X-Git-Tag: firefly_0821_release~13604^2~760
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=5cd2fe6d54c91aa76893b3034f5f3473063c0202;p=firefly-linux-kernel-4.4.55.git

RDS/IW+IB: Set recv ring low water mark to 1/2 full.

Currently the recv ring low water mark is 1/4 the depth.  Performance
measurements show that this limits iWARP throughput by flow controlling
the rds-stress senders.  Setting it to 1/2 seems to max the T3
performance.  I tried even higher levels but that didn't help and it
started to increase the rds thread cpu utilization.

Signed-off-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Andy Grover <andy.grover@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---

diff --git a/net/rds/ib_ring.c b/net/rds/ib_ring.c
index 99a6ccae964c..ff97e8eda858 100644
--- a/net/rds/ib_ring.c
+++ b/net/rds/ib_ring.c
@@ -137,7 +137,7 @@ int rds_ib_ring_empty(struct rds_ib_work_ring *ring)
 
 int rds_ib_ring_low(struct rds_ib_work_ring *ring)
 {
-	return __rds_ib_ring_used(ring) <= (ring->w_nr >> 2);
+	return __rds_ib_ring_used(ring) <= (ring->w_nr >> 1);
 }
 
 /*
diff --git a/net/rds/iw_ring.c b/net/rds/iw_ring.c
index d422d4b5deef..da8e3b63f663 100644
--- a/net/rds/iw_ring.c
+++ b/net/rds/iw_ring.c
@@ -137,7 +137,7 @@ int rds_iw_ring_empty(struct rds_iw_work_ring *ring)
 
 int rds_iw_ring_low(struct rds_iw_work_ring *ring)
 {
-	return __rds_iw_ring_used(ring) <= (ring->w_nr >> 2);
+	return __rds_iw_ring_used(ring) <= (ring->w_nr >> 1);
 }