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authorAndy Grover <andy.grover@oracle.com>2009-07-17 13:13:30 +0000
committerDavid S. Miller <davem@davemloft.net>2009-07-20 08:03:10 -0700
commit68cb01c1ba312add7c7cc7da1bbe98b3071904d1 (patch)
tree2630e1ed3d2101ae88b267888621c035ca901a99 /net/rds
parente11d912a7dd4dfe388f38ba3080a6d067a57b23d (diff)
RDS/IB: Disable flow control in sysctl and explain why
Backwards compatibility with rds 3.0 causes protocol- based flow control to be disabled as a side-effect. I don't want to pull out FC support from the IB transport but I do want to document and keep the sysctl consistent if possible. Signed-off-by: Andy Grover <andy.grover@oracle.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/rds')
-rw-r--r--net/rds/ib_sysctl.c12
1 files changed, 11 insertions, 1 deletions
diff --git a/net/rds/ib_sysctl.c b/net/rds/ib_sysctl.c
index d87830db93a0..84b5ffcb280f 100644
--- a/net/rds/ib_sysctl.c
+++ b/net/rds/ib_sysctl.c
@@ -53,7 +53,17 @@ unsigned long rds_ib_sysctl_max_unsig_bytes = (16 << 20);
static unsigned long rds_ib_sysctl_max_unsig_bytes_min = 1;
static unsigned long rds_ib_sysctl_max_unsig_bytes_max = ~0UL;
-unsigned int rds_ib_sysctl_flow_control = 1;
+/*
+ * This sysctl does nothing.
+ *
+ * Backwards compatibility with RDS 3.0 wire protocol
+ * disables initial FC credit exchange.
+ * If it's ever possible to drop 3.0 support,
+ * setting this to 1 and moving init/refill of send/recv
+ * rings from ib_cm_connect_complete() back into ib_setup_qp()
+ * will cause credits to be added before protocol negotiation.
+ */
+unsigned int rds_ib_sysctl_flow_control = 0;
ctl_table rds_ib_sysctl_table[] = {
{