UCP/API: add estimated bandwidth query to ucp_ep_query

Add UCP_EP_ATTR_FIELD_ESTIMATED_BW field to ucp_ep_attr_t that allows
querying the estimated aggregate bandwidth (bytes/sec) for a given
local/remote memory type pair on an endpoint. The caller sets
local_mem_type and remote_mem_type and the implementation returns the
sum of bandwidths across all data lanes whose memory domain supports
the requested memory type.

Closes #6254

Author: ndg8743

src/ucp/api/ucp.h

@@ -4214,7 +4214,8 @@ enum ucp_ep_attr_field {
     UCP_EP_ATTR_FIELD_LOCAL_SOCKADDR  = UCS_BIT(1), /**< Sockaddr used by the endpoint */
     UCP_EP_ATTR_FIELD_REMOTE_SOCKADDR = UCS_BIT(2), /**< Sockaddr the endpoint is connected to */
     UCP_EP_ATTR_FIELD_TRANSPORTS      = UCS_BIT(3), /**< Transport and device used by endpoint */
-    UCP_EP_ATTR_FIELD_USER_DATA       = UCS_BIT(4)  /**< User data associated with the endpoint */
+    UCP_EP_ATTR_FIELD_USER_DATA       = UCS_BIT(4), /**< User data associated with the endpoint */
+    UCP_EP_ATTR_FIELD_ESTIMATED_BW    = UCS_BIT(5)  /**< Estimated bandwidth for a memory type pair */
 };
 
 
@@ -4268,6 +4269,21 @@ typedef struct ucp_ep_attr {
      * @ref ucp_ep_params_t::user_data.
      */
     void                   *user_data;
+
+    /**
+     * Estimated bandwidth (in bytes/second) for a given pair of local and
+     * remote memory types. The caller sets @ref local_mem_type and
+     * @ref remote_mem_type before calling @ref ucp_ep_query, and the
+     * implementation fills in @ref bandwidth with the aggregate estimated
+     * bandwidth across the endpoint's data lanes that support the requested
+     * memory types.
+     */
+    struct {
+        ucs_memory_type_t  local_mem_type;  /**< [in] Local memory type */
+        ucs_memory_type_t  remote_mem_type; /**< [in] Remote memory type */
+        double             bandwidth;       /**< [out] Estimated bandwidth
+                                                 (bytes/second) */
+    } estimated_bw;
 } ucp_ep_attr_t;
 
 

src/ucp/core/ucp_ep.c

@@ -3976,6 +3976,47 @@ ucs_status_t ucp_ep_query_sockaddr(ucp_ep_h ep, ucp_ep_attr_t *attr)
     return UCS_OK;
 }
 
+static void ucp_ep_query_estimated_bw(ucp_ep_h ep, ucp_ep_attr_t *attr)
+{
+    ucp_worker_h worker        = ep->worker;
+    ucp_context_h context      = worker->context;
+    ucp_ep_config_t *config    = ucp_ep_config(ep);
+    ucs_memory_type_t local_mt = attr->estimated_bw.local_mem_type;
+    double total_bw            = 0.0;
+    ucp_lane_index_t lane;
+    ucp_rsc_index_t rsc_index;
+    ucp_md_index_t md_index;
+    const uct_md_attr_v2_t *md_attr;
+    ucp_worker_iface_t *wiface;
+
+    for (lane = 0; lane < config->key.num_lanes; ++lane) {
+        if (lane == config->key.cm_lane) {
+            continue;
+        }
+
+        rsc_index = config->key.lanes[lane].rsc_index;
+        if (rsc_index == UCP_NULL_RESOURCE) {
+            continue;
+        }
+
+        md_index = config->md_index[lane];
+        md_attr  = &context->tl_mds[md_index].attr;
+
+        /* Check if the lane's memory domain can register the requested local
+         * memory type. Host memory is always assumed to be supported. */
+        if ((local_mt != UCS_MEMORY_TYPE_HOST) &&
+            !(md_attr->reg_mem_types & UCS_BIT(local_mt)) &&
+            !(md_attr->access_mem_types & UCS_BIT(local_mt))) {
+            continue;
+        }
+
+        wiface    = ucp_worker_iface(worker, rsc_index);
+        total_bw += ucp_wireup_iface_bw_distance(wiface);
+    }
+
+    attr->estimated_bw.bandwidth = total_bw;
+}
+
 ucs_status_t ucp_ep_query(ucp_ep_h ep, ucp_ep_attr_t *attr)
 {
     ucs_status_t status;
@@ -4007,6 +4048,10 @@ ucs_status_t ucp_ep_query(ucp_ep_h ep, ucp_ep_attr_t *attr)
         attr->user_data = ep->flags & UCP_EP_FLAG_USER_DATA_PARAM ? ep->ext->user_data : NULL;
     }
 
+    if (attr->field_mask & UCP_EP_ATTR_FIELD_ESTIMATED_BW) {
+        ucp_ep_query_estimated_bw(ep, attr);
+    }
+
     return UCS_OK;
 }