Re: [dpdk-dev] [PATCH v3 6/9] eal: register non-EAL threads as lcores

diff --git a/lib/librte_eal/common/eal_common_lcore.c b/lib/librte_eal/common/eal_common_lcore.c
index 86d32a3dd7..7db05428e7 100644
--- a/lib/librte_eal/common/eal_common_lcore.c
+++ b/lib/librte_eal/common/eal_common_lcore.c

@@ -6,12 +6,13 @@
 #include <limits.h>
 #include <string.h>

-#include <rte_errno.h>
-#include <rte_log.h>
-#include <rte_eal.h>
-#include <rte_lcore.h>
 #include <rte_common.h>
 #include <rte_debug.h>
+#include <rte_eal.h>
+#include <rte_errno.h>
+#include <rte_lcore.h>
+#include <rte_log.h>
+#include <rte_spinlock.h>

 #include "eal_private.h"
 #include "eal_thread.h"

@@ -220,3 +221,38 @@ rte_socket_id_by_idx(unsigned int idx)
 	}
 	return config->numa_nodes[idx];
 }
+
+static rte_spinlock_t lcore_lock = RTE_SPINLOCK_INITIALIZER;
+
+unsigned int
+eal_lcore_non_eal_allocate(void)
+{
+	struct rte_config *cfg = rte_eal_get_configuration();
+	unsigned int lcore_id;
+
+	rte_spinlock_lock(&lcore_lock);

+	for (lcore_id = 0; lcore_id < RTE_MAX_LCORE; lcore_id++) {
+		if (cfg->lcore_role[lcore_id] != ROLE_OFF)
+			continue;
+		cfg->lcore_role[lcore_id] = ROLE_NON_EAL;
+		cfg->lcore_count++;
+		break;
+	}
+	if (lcore_id == RTE_MAX_LCORE)
+		RTE_LOG(DEBUG, EAL, "No lcore available.\n");
+	rte_spinlock_unlock(&lcore_lock);
+	return lcore_id;
+}
+
+void
+eal_lcore_non_eal_release(unsigned int lcore_id)
+{
+	struct rte_config *cfg = rte_eal_get_configuration();
+
+	rte_spinlock_lock(&lcore_lock);
+	if (cfg->lcore_role[lcore_id] == ROLE_NON_EAL) {
+		cfg->lcore_role[lcore_id] = ROLE_OFF;
+		cfg->lcore_count--;
+	}
+	rte_spinlock_unlock(&lcore_lock);
+}

diff --git a/lib/librte_eal/common/eal_common_thread.c b/lib/librte_eal/common/eal_common_thread.c
index a7ae0691bf..1cbddc4b5b 100644
--- a/lib/librte_eal/common/eal_common_thread.c
+++ b/lib/librte_eal/common/eal_common_thread.c

@@ -236,3 +236,36 @@ rte_ctrl_thread_create(pthread_t *thread, const char *name,
 	pthread_join(*thread, NULL);
 	return -ret;
 }
+
+void
+rte_thread_register(void)
+{
+	unsigned int lcore_id;
+	rte_cpuset_t cpuset;
+
+	/* EAL init flushes all lcores, we can't register before. */
+	assert(internal_config.init_complete == 1);
+	if (pthread_getaffinity_np(pthread_self(), sizeof(cpuset),
+			&cpuset) != 0)
+		CPU_ZERO(&cpuset);
+	lcore_id = eal_lcore_non_eal_allocate();
+	if (lcore_id >= RTE_MAX_LCORE)
+		lcore_id = LCORE_ID_ANY;
+	rte_thread_init(lcore_id, &cpuset);

+	if (lcore_id != LCORE_ID_ANY)
+		RTE_LOG(DEBUG, EAL, "Registered non-EAL thread as lcore %u.\n",
+			lcore_id);
+}
+
+void
+rte_thread_unregister(void)
+{
+	unsigned int lcore_id = rte_lcore_id();
+
+	if (lcore_id != LCORE_ID_ANY)
+		eal_lcore_non_eal_release(lcore_id);
+	rte_thread_uninit();
+	if (lcore_id != LCORE_ID_ANY)
+		RTE_LOG(DEBUG, EAL, "Unregistered non-EAL thread (was lcore %u).\n",
+			lcore_id);
+}

diff --git a/lib/librte_eal/common/eal_private.h b/lib/librte_eal/common/eal_private.h
index 0592fcd694..73238ff157 100644
--- a/lib/librte_eal/common/eal_private.h
+++ b/lib/librte_eal/common/eal_private.h

@@ -396,6 +396,24 @@ uint64_t get_tsc_freq(void);
  */
 uint64_t get_tsc_freq_arch(void);

+/**
+ * Allocate a free lcore to associate to a non-EAL thread.
+ *
+ * @return
+ *   - the id of a lcore with role ROLE_NON_EAL on success.
+ *   - RTE_MAX_LCORE if none was available.
+ */
+unsigned int eal_lcore_non_eal_allocate(void);
+
+/**
+ * Release the lcore used by a non-EAL thread.
+ * Counterpart of eal_lcore_non_eal_allocate().
+ *
+ * @param lcore_id
+ *   The lcore with role ROLE_NON_EAL to release.
+ */
+void eal_lcore_non_eal_release(unsigned int lcore_id);
+
 /**
  * Prepare physical memory mapping
  * i.e. hugepages on Linux and

diff --git a/lib/librte_eal/include/rte_lcore.h b/lib/librte_eal/include/rte_lcore.h
index 3968c40693..ea86220394 100644
--- a/lib/librte_eal/include/rte_lcore.h
+++ b/lib/librte_eal/include/rte_lcore.h

@@ -31,6 +31,7 @@ enum rte_lcore_role_t {
 	ROLE_RTE,
 	ROLE_OFF,
 	ROLE_SERVICE,
+	ROLE_NON_EAL,
 };

 /**

@@ -67,7 +68,8 @@ rte_lcore_has_role(unsigned int lcore_id, enum rte_lcore_role_t role);
  *   to run threads with lcore IDs 0, 1, 2 and 3 on physical core 10..
  *
  * @return
- *  Logical core ID (in EAL thread) or LCORE_ID_ANY (in non-EAL thread)
+ *  Logical core ID (in EAL thread or registered non-EAL thread) or
+ *  LCORE_ID_ANY (in unregistered non-EAL thread)
  */
 static inline unsigned
 rte_lcore_id(void)

@@ -279,6 +281,20 @@ int rte_thread_setname(pthread_t id, const char *name);
 __rte_experimental
 int rte_thread_getname(pthread_t id, char *name, size_t len);

+/**
+ * Register current non-EAL thread as a lcore.
+ */
+__rte_experimental
+void
+rte_thread_register(void);
+
+/**
+ * Unregister current thread and release lcore if one was associated.
+ */
+__rte_experimental
+void
+rte_thread_unregister(void);
+
 /**
  * Create a control thread.
  *

diff --git a/lib/librte_eal/rte_eal_version.map b/lib/librte_eal/rte_eal_version.map
index 5831eea4b0..39c41d445d 100644
--- a/lib/librte_eal/rte_eal_version.map
+++ b/lib/librte_eal/rte_eal_version.map

@@ -396,6 +396,8 @@ EXPERIMENTAL {

 	# added in 20.08
 	__rte_trace_mem_per_thread_free;
+	rte_thread_register;
+	rte_thread_unregister;
 };

 INTERNAL {

diff --git a/lib/librte_mempool/rte_mempool.h b/lib/librte_mempool/rte_mempool.h
index 652d19f9f1..9e0ee052b3 100644
--- a/lib/librte_mempool/rte_mempool.h
+++ b/lib/librte_mempool/rte_mempool.h

@@ -28,9 +28,9 @@
  * rte_mempool_get() or rte_mempool_put() are designed to be called from an EAL
  * thread due to the internal per-lcore cache. Due to the lack of caching,
  * rte_mempool_get() or rte_mempool_put() performance will suffer when called
- * by non-EAL threads. Instead, non-EAL threads should call
- * rte_mempool_generic_get() or rte_mempool_generic_put() with a user cache
- * created with rte_mempool_cache_create().
+ * by unregistered non-EAL threads. Instead, unregistered non-EAL threads
+ * should call rte_mempool_generic_get() or rte_mempool_generic_put() with a
+ * user cache created with rte_mempool_cache_create().
  */

 #include <stdio.h>

@@ -1233,7 +1233,7 @@ void rte_mempool_dump(FILE *f, struct rte_mempool *mp);
 /**
  * Create a user-owned mempool cache.
  *
- * This can be used by non-EAL threads to enable caching when they
+ * This can be used by unregistered non-EAL threads to enable caching when they
  * interact with a mempool.
  *
  * @param size

@@ -1264,7 +1264,8 @@ rte_mempool_cache_free(struct rte_mempool_cache *cache);
  * @param lcore_id
  *   The logical core id.
  * @return
- *   A pointer to the mempool cache or NULL if disabled or non-EAL thread.
+ *   A pointer to the mempool cache or NULL if disabled or unregistered non-EAL
+ *   thread.
  */
 static __rte_always_inline struct rte_mempool_cache *
 rte_mempool_default_cache(struct rte_mempool *mp, unsigned lcore_id)
--

2.23.0