diff mbox series

[v2,08/10] service: identify service running on another core correctly

Message ID 1583999071-22872-9-git-send-email-phil.yang@arm.com
State Superseded
Headers show
Series None | expand

Commit Message

Phil Yang March 12, 2020, 7:44 a.m. UTC 
From: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>


The logic to identify if the MT unsafe service is running on another
core can return -EBUSY spuriously. In such cases, running the service
becomes costlier than using atomic operations. Assume that the
application passes the right parameters and reduces the number of
instructions for all cases.

Cc: stable@dpdk.org

Signed-off-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>

Reviewed-by: Phil Yang <phil.yang@arm.com>

Reviewed-by: Gavin Hu <gavin.hu@arm.com>

---
 lib/librte_eal/common/rte_service.c | 26 ++++++++------------------
 1 file changed, 8 insertions(+), 18 deletions(-)

-- 
2.7.4
diff mbox series

Patch

diff --git a/lib/librte_eal/common/rte_service.c b/lib/librte_eal/common/rte_service.c
index b37fc56..670f5a9 100644
--- a/lib/librte_eal/common/rte_service.c
+++ b/lib/librte_eal/common/rte_service.c
@@ -357,7 +357,7 @@  service_runner_do_callback(struct rte_service_spec_impl *s,
 /* Expects the service 's' is valid. */
 static int32_t
 service_run(uint32_t i, struct core_state *cs, uint64_t service_mask,
-	    struct rte_service_spec_impl *s)
+	    struct rte_service_spec_impl *s, uint32_t serialize_mt_unsafe)
 {
 	if (!s)
 		return -EINVAL;
@@ -371,7 +371,7 @@  service_run(uint32_t i, struct core_state *cs, uint64_t service_mask,
 
 	cs->service_active_on_lcore[i] = 1;
 
-	if (service_mt_safe(s) == 0) {
+	if ((service_mt_safe(s) == 0) && (serialize_mt_unsafe == 1)) {
 		if (!rte_atomic32_cmpset((uint32_t *)&s->execute_lock, 0, 1))
 			return -EBUSY;
 
@@ -409,24 +409,14 @@  rte_service_run_iter_on_app_lcore(uint32_t id, uint32_t serialize_mt_unsafe)
 
 	SERVICE_VALID_GET_OR_ERR_RET(id, s, -EINVAL);
 
-	/* Atomically add this core to the mapped cores first, then examine if
-	 * we can run the service. This avoids a race condition between
-	 * checking the value, and atomically adding to the mapped count.
+	/* Increment num_mapped_cores to indicate that the service
+	 * is running on a core.
 	 */
-	if (serialize_mt_unsafe)
-		rte_atomic32_inc(&s->num_mapped_cores);
+	rte_atomic32_inc(&s->num_mapped_cores);
 
-	if (service_mt_safe(s) == 0 &&
-			rte_atomic32_read(&s->num_mapped_cores) > 1) {
-		if (serialize_mt_unsafe)
-			rte_atomic32_dec(&s->num_mapped_cores);
-		return -EBUSY;
-	}
-
-	int ret = service_run(id, cs, UINT64_MAX, s);
+	int ret = service_run(id, cs, UINT64_MAX, s, serialize_mt_unsafe);
 
-	if (serialize_mt_unsafe)
-		rte_atomic32_dec(&s->num_mapped_cores);
+	rte_atomic32_dec(&s->num_mapped_cores);
 
 	return ret;
 }
@@ -446,7 +436,7 @@  service_runner_func(void *arg)
 			if (!service_valid(i))
 				continue;
 			/* return value ignored as no change to code flow */
-			service_run(i, cs, service_mask, service_get(i));
+			service_run(i, cs, service_mask, service_get(i), 1);
 		}
 
 		cs->loops++;