service: add function to run on app lcore

This commit adds a new function which allows an application lcore
(aka; *not* a dedicated service-lcore) to run a service. This
function is required to allow applications to gradually port
functionality to using services, while still being able to run
ordinary application functions.

This requirement became clear when a patch to the existing
eventdev/pipeline sample app was modified to use a service-core
for scheduling - and that same core should be capable of running
the "worker()" function from the application too.

This patch refactors the existing running code into a smaller
"service_run" function, which can be called by the dedicated
service-core loop, and the newly added function.

[1] http://dpdk.org/ml/archives/dev/2017-October/079876.html

Signed-off-by: Harry van Haaren <harry.van.haaren@intel.com>
Acked-by: Pavan Nikhilesh <pbhagavatula@caviumnetworks.com>

diff --git a/lib/librte_eal/common/include/rte_service.h b/lib/librte_eal/common/include/rte_service.h
index 21da739..63d3170 100644 (file)
--- a/lib/librte_eal/common/include/rte_service.h
+++ b/lib/librte_eal/common/include/rte_service.h
@@ -207,6 +207,27 @@ int32_t rte_service_runstate_set(uint32_t id, uint32_t runstate);
  */
 int32_t rte_service_runstate_get(uint32_t id);
 
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change without prior notice
+ *
+ * This function runs a service callback from a non-service lcore context.
+ * The *id* of the service to be run is passed in, and the service-callback
+ * is executed on the calling lcore immediately if possible. If the service is
+ * not multi-thread capable and another thread is currently executing it, this
+ * function returns without running the callback.
+ *
+ * Note that any thread calling this function MUST be a DPDK EAL thread, as
+ * the *rte_lcore_id* function is used to access internal data structures.
+ *
+ * @retval 0 Service was run on the calling thread successfully
+ * @retval -EBUSY Another lcore is executing the service, and it is not a
+ *         multi-thread safe service, so the service was not run on this lcore
+ * @retval -ENOEXEC Service is not in a runnable state
+ * @retval -EINVAL Invalid service id
+ */
+int32_t rte_service_run_iter_on_app_lcore(uint32_t id);
+
 /**
  * @warning
  * @b EXPERIMENTAL: this API may change without prior notice

diff --git a/lib/librte_eal/common/rte_service.c b/lib/librte_eal/common/rte_service.c
index e598e16..4e27f75 100644 (file)
--- a/lib/librte_eal/common/rte_service.c
+++ b/lib/librte_eal/common/rte_service.c
@@ -331,6 +331,42 @@ rte_service_runner_do_callback(struct rte_service_spec_impl *s,
                s->spec.callback(userdata);
 }
 
+
+static inline int32_t
+service_run(uint32_t i, struct core_state *cs, uint64_t service_mask)
+{
+       if (!service_valid(i))
+               return -EINVAL;
+       struct rte_service_spec_impl *s = &rte_services[i];
+       if (s->comp_runstate != RUNSTATE_RUNNING ||
+                       s->app_runstate != RUNSTATE_RUNNING ||
+                       !(service_mask & (UINT64_C(1) << i)))
+               return -ENOEXEC;
+
+       /* check do we need cmpset, if MT safe or <= 1 core
+        * mapped, atomic ops are not required.
+        */
+       const int use_atomics = (service_mt_safe(s) == 0) &&
+                               (s->num_mapped_cores > 1);
+       if (use_atomics) {
+               if (!rte_atomic32_cmpset((uint32_t *)&s->execute_lock, 0, 1))
+                       return -EBUSY;
+
+               rte_service_runner_do_callback(s, cs, i);
+               rte_atomic32_clear(&s->execute_lock);
+       } else
+               rte_service_runner_do_callback(s, cs, i);
+
+       return 0;
+}
+
+int32_t rte_service_run_iter_on_app_lcore(uint32_t id)
+{
+       /* run service on calling core, using all-ones as the service mask */
+       struct core_state *cs = &lcore_states[rte_lcore_id()];
+       return service_run(id, cs, UINT64_MAX);
+}
+
 static int32_t
 rte_service_runner_func(void *arg)
 {
@@ -343,27 +379,8 @@ rte_service_runner_func(void *arg)
                const uint64_t service_mask = cs->service_mask;
 
                for (i = 0; i < RTE_SERVICE_NUM_MAX; i++) {
-                       if (!service_valid(i))
-                               continue;
-                       struct rte_service_spec_impl *s = &rte_services[i];
-                       if (s->comp_runstate != RUNSTATE_RUNNING ||
-                                       s->app_runstate != RUNSTATE_RUNNING ||
-                                       !(service_mask & (UINT64_C(1) << i)))
-                               continue;
-
-                       /* check do we need cmpset, if MT safe or <= 1 core
-                        * mapped, atomic ops are not required.
-                        */
-                       const int use_atomics = (service_mt_safe(s) == 0) &&
-                                               (s->num_mapped_cores > 1);
-                       if (use_atomics) {
-                               uint32_t *lock = (uint32_t *)&s->execute_lock;
-                               if (rte_atomic32_cmpset(lock, 0, 1)) {
-                                       rte_service_runner_do_callback(s, cs, i);
-                                       rte_atomic32_clear(&s->execute_lock);
-                               }
-                       } else
-                               rte_service_runner_do_callback(s, cs, i);
+                       /* return value ignored as no change to code flow */
+                       service_run(i, cs, service_mask);
                }
 
                rte_smp_rmb();

diff --git a/lib/librte_eal/rte_eal_version.map b/lib/librte_eal/rte_eal_version.map
index 8802b28..4be9008 100644 (file)
--- a/lib/librte_eal/rte_eal_version.map
+++ b/lib/librte_eal/rte_eal_version.map
@@ -229,6 +229,7 @@ EXPERIMENTAL {
        rte_service_map_lcore_set;
        rte_service_probe_capability;
        rte_service_reset;
+       rte_service_run_iter_on_app_lcore;
        rte_service_runstate_get;
        rte_service_runstate_set;
        rte_service_set_stats_enable;