[dpdk-dev] [RFC 4/4] eal: set affinity for control threads

[Olivier Matz <olivier.matz@6wind.com>]

The management threads must not bother the dataplane or service cores.
Set the affinity of these threads accordingly.

Signed-off-by: Olivier Matz <olivier.matz@6wind.com>
---
 lib/librte_eal/common/eal_common_thread.c | 20 +++++++++++++++++++-
 lib/librte_eal/common/include/rte_lcore.h |  4 +++-
 2 files changed, 22 insertions(+), 2 deletions(-)

diff --git a/lib/librte_eal/common/eal_common_thread.c b/lib/librte_eal/common/eal_common_thread.c
index b4335e04e..f1798cebc 100644
--- a/lib/librte_eal/common/eal_common_thread.c
+++ b/lib/librte_eal/common/eal_common_thread.c
@@ -45,6 +45,7 @@
 #include <rte_memory.h>
 #include <rte_log.h>
 
+#include "eal_private.h"
 #include "eal_thread.h"
 
 RTE_DECLARE_PER_LCORE(unsigned , _socket_id);
@@ -199,7 +200,9 @@ int rte_ctrl_thread_create(pthread_t *thread, const char *name,
 		.start_routine = start_routine,
 		.arg = arg,
 	};
-	int ret;
+	unsigned int lcore_id;
+	rte_cpuset_t cpuset;
+	int set_affinity, ret;
 
 	pthread_barrier_init(&params.launched, NULL, 2);
 	pthread_barrier_init(&params.configured, NULL, 2);
@@ -216,6 +219,21 @@ int rte_ctrl_thread_create(pthread_t *thread, const char *name,
 			goto fail;
 	}
 
+	set_affinity = 0;
+	CPU_ZERO(&cpuset);
+	for (lcore_id = 0; lcore_id < RTE_MAX_LCORE; lcore_id++) {
+		if (eal_cpu_detected(lcore_id) &&
+				rte_lcore_has_role(lcore_id, ROLE_OFF)) {
+			CPU_SET(lcore_id, &cpuset);
+			set_affinity = 1;
+		}
+	}
+	if (set_affinity) {
+		ret = pthread_setaffinity_np(*thread, sizeof(cpuset), &cpuset);
+		if (ret < 0)
+			goto fail;
+	}
+
 	pthread_barrier_wait(&params.configured);
 
 	return 0;
diff --git a/lib/librte_eal/common/include/rte_lcore.h b/lib/librte_eal/common/include/rte_lcore.h
index f7f67868c..0d85a91a8 100644
--- a/lib/librte_eal/common/include/rte_lcore.h
+++ b/lib/librte_eal/common/include/rte_lcore.h
@@ -265,7 +265,9 @@ int rte_thread_setname(pthread_t id, const char *name);
 /**
  * Create a control thread.
  *
- * Wrapper to pthread_create() and pthread_setname_np().
+ * Wrapper to pthread_create(), pthread_setname_np() and
+ * pthread_setaffinity_np(). The dataplane and service lcores are
+ * excluded from the affinity of the new thread.
  *
  * @param thread
  *   Filled with the thread id of the new created thread.
-- 
2.11.0