[ofa-general] [PATCH 3/5] [uDAPL v2] dapl scm: add mtu adjustments via environment, default = 1024

[Arlin Davis]

DAPL_IB_MTU adjusts path mtu setting for RC qp's. Default setting
is min of 1024 and active mtu on IB device.

Signed-off by: Arlin Davis ardavis at ichips.intel.com
---
 dapl/openib_scm/dapl_ib_util.c |   27 +++++++++++++++++++++++----
 dapl/openib_scm/dapl_ib_util.h |    1 +
 2 files changed, 24 insertions(+), 4 deletions(-)

diff --git a/dapl/openib_scm/dapl_ib_util.c b/dapl/openib_scm/dapl_ib_util.c
index 0f24737..f7ee58b 100644
--- a/dapl/openib_scm/dapl_ib_util.c
+++ b/dapl/openib_scm/dapl_ib_util.c
@@ -64,6 +64,18 @@ static const char rcsid[] = "$Id:  $";
 int g_dapl_loopback_connection = 0;
 int g_scm_pipe[2];
 
+enum ibv_mtu dapl_ib_mtu(int mtu)
+{
+	switch (mtu) {
+	case 256:  return IBV_MTU_256;
+	case 512:  return IBV_MTU_512;
+	case 1024: return IBV_MTU_1024;
+	case 2048: return IBV_MTU_2048;
+	case 4096: return IBV_MTU_4096;
+	default:   return IBV_MTU_1024;
+	}
+}
+
 /* just get IP address for hostname */
 DAT_RETURN getipaddr( char *addr, int addr_len)
 {
@@ -223,6 +235,8 @@ found:
 		dapl_os_get_env_val("DAPL_HOP_LIMIT", SCM_HOP_LIMIT);
 	hca_ptr->ib_trans.tclass =
 		dapl_os_get_env_val("DAPL_TCLASS", SCM_TCLASS);
+	hca_ptr->ib_trans.mtu =
+		dapl_ib_mtu(dapl_os_get_env_val("DAPL_IB_MTU", SCM_IB_MTU));
 
 	/* initialize cq_lock */
 	dat_status = dapl_os_lock_init(&hca_ptr->ib_trans.cq_lock);
@@ -448,19 +462,24 @@ DAT_RETURN dapls_ib_query_hca (
                 ia_attr->extension_supported = DAT_EXTENSION_IB;
                 ia_attr->extension_version = DAT_IB_EXTENSION_VERSION;
 #endif
-		hca_ptr->ib_trans.mtu = port_attr.active_mtu;
+		hca_ptr->ib_trans.mtu = DAPL_MIN(port_attr.active_mtu,
+						 hca_ptr->ib_trans.mtu);
 		hca_ptr->ib_trans.ack_timer = 
 			DAPL_MAX(dev_attr.local_ca_ack_delay,
 				 hca_ptr->ib_trans.ack_timer);
 
 		dapl_dbg_log (DAPL_DBG_TYPE_UTIL, 
-			" query_hca: (%x.%x) ep %d ep_q %d evd %d evd_q %d\n", 
+			" query_hca: (%x.%x) ep %d ep_q %d evd %d"
+			" evd_q %d mtu %d\n", 
 			ia_attr->hardware_version_major,
 			ia_attr->hardware_version_minor,
 			ia_attr->max_eps, ia_attr->max_dto_per_ep,
-			ia_attr->max_evds, ia_attr->max_evd_qlen );
+			ia_attr->max_evds, ia_attr->max_evd_qlen,
+			128 << hca_ptr->ib_trans.mtu);
+
 		dapl_dbg_log (DAPL_DBG_TYPE_UTIL, 
-			" query_hca: msg %llu rdma %llu iov %d lmr %d rmr %d ack_time %d\n", 
+			" query_hca: msg %llu rdma %llu iov %d lmr %d rmr %d"
+			" ack_time %d\n", 
 			ia_attr->max_message_size, ia_attr->max_rdma_size,
 			ia_attr->max_iov_segments_per_dto, ia_attr->max_lmrs, 
 			ia_attr->max_rmrs,hca_ptr->ib_trans.ack_timer );
diff --git a/dapl/openib_scm/dapl_ib_util.h b/dapl/openib_scm/dapl_ib_util.h
index deb6be3..bd702a9 100644
--- a/dapl/openib_scm/dapl_ib_util.h
+++ b/dapl/openib_scm/dapl_ib_util.h
@@ -196,6 +196,7 @@ typedef struct ibv_comp_channel *ib_wait_obj_handle_t;
 #define SCM_ACK_RETRY 7		/* 3 bits, 7 * 134ms = 940ms */
 #define SCM_RNR_TIMER 28	/* 5 bits, 28 == 163ms, 31 == 491ms */
 #define SCM_RNR_RETRY 7		/* 3 bits, 7 == infinite */
+#define SCM_IB_MTU    1024
 
 /* Global routing defaults */
 #define SCM_GLOBAL	0	/* global routing is disabled */
-- 
1.5.2.5