[dpdk-dev] [RFC v2 02/23] eal: add function to report number of detected sockets

[Anatoly Burakov <anatoly.burakov@intel.com>]

At the moment, we always rely on scanning everything for every
socket up until RTE_MAX_NUMA_NODES and checking if there's a memseg
associated with each socket if we want to find out how many sockets
we actually have. This becomes a problem when we may have memory on
socket but it's not allocated yet, so we do the detection on lcore
scan instead, and store the value for later use.

Signed-off-by: Anatoly Burakov <anatoly.burakov@intel.com>
---
 lib/librte_eal/common/eal_common_lcore.c  | 11 +++++++++++
 lib/librte_eal/common/include/rte_eal.h   |  1 +
 lib/librte_eal/common/include/rte_lcore.h |  8 ++++++++
 3 files changed, 20 insertions(+)

diff --git a/lib/librte_eal/common/eal_common_lcore.c b/lib/librte_eal/common/eal_common_lcore.c
index 0db1555..7566a6b 100644
--- a/lib/librte_eal/common/eal_common_lcore.c
+++ b/lib/librte_eal/common/eal_common_lcore.c
@@ -57,6 +57,7 @@ rte_eal_cpu_init(void)
 	struct rte_config *config = rte_eal_get_configuration();
 	unsigned lcore_id;
 	unsigned count = 0;
+	unsigned max_socket_id = 0;
 
 	/*
 	 * Parse the maximum set of logical cores, detect the subset of running
@@ -100,6 +101,8 @@ rte_eal_cpu_init(void)
 				lcore_id, lcore_config[lcore_id].core_id,
 				lcore_config[lcore_id].socket_id);
 		count++;
+		max_socket_id = RTE_MAX(max_socket_id,
+					lcore_config[lcore_id].socket_id);
 	}
 	/* Set the count of enabled logical cores of the EAL configuration */
 	config->lcore_count = count;
@@ -108,5 +111,13 @@ rte_eal_cpu_init(void)
 		RTE_MAX_LCORE);
 	RTE_LOG(INFO, EAL, "Detected %u lcore(s)\n", config->lcore_count);
 
+	config->numa_node_count = max_socket_id + 1;
+	RTE_LOG(INFO, EAL, "Detected %u NUMA nodes\n", config->numa_node_count);
+
 	return 0;
 }
+
+unsigned rte_num_sockets(void) {
+	const struct rte_config *config = rte_eal_get_configuration();
+	return config->numa_node_count;
+}
diff --git a/lib/librte_eal/common/include/rte_eal.h b/lib/librte_eal/common/include/rte_eal.h
index 8e4e71c..5b12914 100644
--- a/lib/librte_eal/common/include/rte_eal.h
+++ b/lib/librte_eal/common/include/rte_eal.h
@@ -83,6 +83,7 @@ enum rte_proc_type_t {
 struct rte_config {
 	uint32_t master_lcore;       /**< Id of the master lcore */
 	uint32_t lcore_count;        /**< Number of available logical cores. */
+	uint32_t numa_node_count;    /**< Number of detected NUMA nodes. */
 	uint32_t service_lcore_count;/**< Number of available service cores. */
 	enum rte_lcore_role_t lcore_role[RTE_MAX_LCORE]; /**< State of cores. */
 
diff --git a/lib/librte_eal/common/include/rte_lcore.h b/lib/librte_eal/common/include/rte_lcore.h
index c89e6ba..6a75c9b 100644
--- a/lib/librte_eal/common/include/rte_lcore.h
+++ b/lib/librte_eal/common/include/rte_lcore.h
@@ -148,6 +148,14 @@ rte_lcore_index(int lcore_id)
 unsigned rte_socket_id(void);
 
 /**
+ * Return number of physical sockets on the system.
+ * @return
+ *   the number of physical sockets as recognized by EAL
+ *
+ */
+unsigned rte_num_sockets(void);
+
+/**
  * Get the ID of the physical socket of the specified lcore
  *
  * @param lcore_id
-- 
2.7.4