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From: Phil Yang <phil.yang@arm.com>
To: phil.yang@arm.com
Cc: nd@arm.com, Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>,
	stable@dpdk.org
Subject: [dpdk-stable] [PATCH v2 08/10] service: identify service running on another core correctly
Date: Thu, 12 Mar 2020 14:13:42 +0800	[thread overview]
Message-ID: <1583993624-20446-9-git-send-email-phil.yang@arm.com> (raw)
In-Reply-To: <1583993624-20446-1-git-send-email-phil.yang@arm.com>

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 more costlier than using atomic operations. Assume that the
application passes the right parameters and reduce 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>
---
 lib/librte_eal/common/rte_service.c | 26 ++++++++------------------
 1 file changed, 8 insertions(+), 18 deletions(-)

diff --git a/lib/librte_eal/common/rte_service.c b/lib/librte_eal/common/rte_service.c
index b37fc56..0186024 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
+	 * 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++;
-- 
2.7.4


  parent reply	other threads:[~2020-03-12  6:14 UTC|newest]

Thread overview: 51+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <1583862551-2049-1-git-send-email-phil.yang@arm.com>
2020-03-10 17:49 ` [dpdk-stable] [PATCH 05/10] service: remove rte prefix from static functions Phil Yang
2020-03-10 17:49 ` [dpdk-stable] [PATCH 06/10] service: remove redundant code Phil Yang
2020-03-10 17:49 ` [dpdk-stable] [PATCH 07/10] service: avoid race condition for MT unsafe service Phil Yang
2020-03-10 17:49 ` [dpdk-stable] [PATCH 08/10] service: identify service running on another core correctly Phil Yang
     [not found] ` <1583993624-20446-1-git-send-email-phil.yang@arm.com>
2020-03-12  6:13   ` [dpdk-stable] [PATCH v2 05/10] service: remove rte prefix from static functions Phil Yang
2020-03-12  6:13   ` [dpdk-stable] [PATCH v2 06/10] service: remove redundant code Phil Yang
2020-03-12  6:13   ` [dpdk-stable] [PATCH v2 07/10] service: avoid race condition for MT unsafe service Phil Yang
2020-03-12  6:13   ` Phil Yang [this message]
     [not found] ` <1583999071-22872-1-git-send-email-phil.yang@arm.com>
2020-03-12  7:44   ` [dpdk-stable] [PATCH v2 05/10] service: remove rte prefix from static functions Phil Yang
2020-03-12  7:44   ` [dpdk-stable] [PATCH v2 06/10] service: remove redundant code Phil Yang
2020-03-12  7:44   ` [dpdk-stable] [PATCH v2 07/10] service: avoid race condition for MT unsafe service Phil Yang
2020-03-12  7:44   ` [dpdk-stable] [PATCH v2 08/10] service: identify service running on another core correctly Phil Yang
     [not found]   ` <1584407863-774-1-git-send-email-phil.yang@arm.com>
2020-03-17  1:17     ` [dpdk-stable] [PATCH v3 07/12] service: remove rte prefix from static functions Phil Yang
2020-04-03 11:57       ` Van Haaren, Harry
2020-04-08 10:14         ` Phil Yang
2020-04-08 10:36           ` Van Haaren, Harry
2020-04-08 10:49             ` Phil Yang
2020-04-05 21:35       ` Honnappa Nagarahalli
2020-04-08 10:14         ` Phil Yang
     [not found]       ` <1587659482-27133-1-git-send-email-phil.yang@arm.com>
2020-04-23 16:31         ` [dpdk-stable] [PATCH v2 1/6] service: fix race condition for MT unsafe service Phil Yang
2020-04-29 16:51           ` Van Haaren, Harry
2020-04-29 22:48             ` Honnappa Nagarahalli
2020-05-01 14:21               ` Van Haaren, Harry
2020-05-01 14:56                 ` Honnappa Nagarahalli
2020-05-01 17:51                   ` Van Haaren, Harry
2020-04-23 16:31         ` [dpdk-stable] [PATCH v2 2/6] service: identify service running on another core correctly Phil Yang
     [not found]         ` <20200502000245.11071-1-honnappa.nagarahalli@arm.com>
2020-05-02  0:02           ` [dpdk-stable] [PATCH v3 1/6] service: fix race condition for MT unsafe service Honnappa Nagarahalli
2020-05-05 14:48             ` Van Haaren, Harry
2020-05-02  0:02           ` [dpdk-stable] [PATCH v3 2/6] service: identify service running on another core correctly Honnappa Nagarahalli
2020-05-05 14:48             ` Van Haaren, Harry
     [not found]         ` <20200505211732.25291-1-honnappa.nagarahalli@arm.com>
2020-05-05 21:17           ` [dpdk-stable] [PATCH v4 1/6] service: fix race condition for MT unsafe service Honnappa Nagarahalli
2020-05-05 21:17           ` [dpdk-stable] [PATCH v4 2/6] service: fix identification of service running on other lcore Honnappa Nagarahalli
     [not found]           ` <1588760683-11027-1-git-send-email-phil.yang@arm.com>
2020-05-06 10:24             ` [dpdk-stable] [PATCH v5 1/6] service: fix race condition for MT unsafe service Phil Yang
2020-05-06 10:24             ` [dpdk-stable] [PATCH v5 2/6] service: fix identification of service running on other lcore Phil Yang
     [not found]             ` <1588778884-13047-1-git-send-email-phil.yang@arm.com>
2020-05-06 15:27               ` [dpdk-stable] [PATCH v6 1/6] service: fix race condition for MT unsafe service Phil Yang
2020-05-06 15:28               ` [dpdk-stable] [PATCH v6 2/6] service: fix identification of service running on other lcore Phil Yang
2020-03-17  1:17     ` [dpdk-stable] [PATCH v3 08/12] service: remove redundant code Phil Yang
2020-04-03 11:58       ` Van Haaren, Harry
2020-04-05 18:35         ` Honnappa Nagarahalli
2020-04-08 10:15           ` Phil Yang
2020-03-17  1:17     ` [dpdk-stable] [PATCH v3 09/12] service: avoid race condition for MT unsafe service Phil Yang
2020-04-03 11:58       ` Van Haaren, Harry
2020-04-04 18:03         ` Honnappa Nagarahalli
2020-04-08 18:05           ` Van Haaren, Harry
2020-04-09  1:31             ` Honnappa Nagarahalli
2020-04-09 16:46               ` Van Haaren, Harry
2020-04-18  6:21                 ` Honnappa Nagarahalli
2020-04-21 17:43                   ` Van Haaren, Harry
2020-03-17  1:17     ` [dpdk-stable] [PATCH v3 10/12] service: identify service running on another core correctly Phil Yang
2020-04-03 11:58       ` Van Haaren, Harry
2020-04-05  2:43         ` Honnappa Nagarahalli

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