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service: relax barriers with C11 atomics

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The runstate, comp_runstate and app_runstate are used as guard variables
in the service core lib. To guarantee the inter-threads visibility of
these guard variables, it uses rte_smp_r/wmb. This patch use c11 atomic
built-ins to relax these barriers.

Signed-off-by: Phil Yang <phil.yang@arm.com>
Reviewed-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>
Acked-by: Harry van Haaren <harry.van.haaren@intel.com>
This commit is contained in:
Phil Yang 2020-05-06 23:28:04 +08:00 committed by David Marchand
parent 41e8227e20
commit 205032bbfc
1 changed files with 85 additions and 32 deletions
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117
lib/librte_eal/common/rte_service.c
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@ -265,7 +265,6 @@ rte_service_component_register(const struct rte_service_spec *spec,
s->spec = *spec;
s->internal_flags |= SERVICE_F_REGISTERED | SERVICE_F_START_CHECK;
rte_smp_wmb();
rte_service_count++;
if (id_ptr)
@ -282,7 +281,6 @@ rte_service_component_unregister(uint32_t id)
SERVICE_VALID_GET_OR_ERR_RET(id, s, -EINVAL);
rte_service_count--;
rte_smp_wmb();
s->internal_flags &= ~(SERVICE_F_REGISTERED);
@ -301,12 +299,17 @@ rte_service_component_runstate_set(uint32_t id, uint32_t runstate)
struct rte_service_spec_impl *s;
SERVICE_VALID_GET_OR_ERR_RET(id, s, -EINVAL);
/* comp_runstate act as the guard variable. Use store-release
* memory order. This synchronizes with load-acquire in
* service_run and service_runstate_get function.
*/
if (runstate)
s->comp_runstate = RUNSTATE_RUNNING;
__atomic_store_n(&s->comp_runstate, RUNSTATE_RUNNING,
__ATOMIC_RELEASE);
else
s->comp_runstate = RUNSTATE_STOPPED;
__atomic_store_n(&s->comp_runstate, RUNSTATE_STOPPED,
__ATOMIC_RELEASE);
rte_smp_wmb();
return 0;
}
@ -316,12 +319,17 @@ rte_service_runstate_set(uint32_t id, uint32_t runstate)
struct rte_service_spec_impl *s;
SERVICE_VALID_GET_OR_ERR_RET(id, s, -EINVAL);
/* app_runstate act as the guard variable. Use store-release
* memory order. This synchronizes with load-acquire in
* service_run runstate_get function.
*/
if (runstate)
s->app_runstate = RUNSTATE_RUNNING;
__atomic_store_n(&s->app_runstate, RUNSTATE_RUNNING,
__ATOMIC_RELEASE);
else
s->app_runstate = RUNSTATE_STOPPED;
__atomic_store_n(&s->app_runstate, RUNSTATE_STOPPED,
__ATOMIC_RELEASE);
rte_smp_wmb();
return 0;
}
@ -330,15 +338,24 @@ rte_service_runstate_get(uint32_t id)
{
struct rte_service_spec_impl *s;
SERVICE_VALID_GET_OR_ERR_RET(id, s, -EINVAL);
rte_smp_rmb();
int check_disabled = !(s->internal_flags & SERVICE_F_START_CHECK);
int lcore_mapped = (__atomic_load_n(&s->num_mapped_cores,
__ATOMIC_RELAXED) > 0);
/* comp_runstate and app_runstate act as the guard variables.
* Use load-acquire memory order. This synchronizes with
* store-release in service state set functions.
*/
if (__atomic_load_n(&s->comp_runstate, __ATOMIC_ACQUIRE) ==
RUNSTATE_RUNNING &&
__atomic_load_n(&s->app_runstate, __ATOMIC_ACQUIRE) ==
RUNSTATE_RUNNING) {
int check_disabled = !(s->internal_flags &
SERVICE_F_START_CHECK);
int lcore_mapped = (__atomic_load_n(&s->num_mapped_cores,
__ATOMIC_RELAXED) > 0);
return (check_disabled | lcore_mapped);
} else
return 0;
return (s->app_runstate == RUNSTATE_RUNNING) &&
(s->comp_runstate == RUNSTATE_RUNNING) &&
(check_disabled | lcore_mapped);
}
static inline void
@ -367,9 +384,15 @@ service_run(uint32_t i, struct core_state *cs, uint64_t service_mask,
if (!s)
return -EINVAL;
if (s->comp_runstate != RUNSTATE_RUNNING ||
s->app_runstate != RUNSTATE_RUNNING ||
!(service_mask & (UINT64_C(1) << i))) {
/* comp_runstate and app_runstate act as the guard variables.
* Use load-acquire memory order. This synchronizes with
* store-release in service state set functions.
*/
if (__atomic_load_n(&s->comp_runstate, __ATOMIC_ACQUIRE) !=
RUNSTATE_RUNNING ||
__atomic_load_n(&s->app_runstate, __ATOMIC_ACQUIRE) !=
RUNSTATE_RUNNING ||
!(service_mask & (UINT64_C(1) << i))) {
cs->service_active_on_lcore[i] = 0;
return -ENOEXEC;
}
@ -434,7 +457,12 @@ service_runner_func(void *arg)
const int lcore = rte_lcore_id();
struct core_state *cs = &lcore_states[lcore];
while (cs->runstate == RUNSTATE_RUNNING) {
/* runstate act as the guard variable. Use load-acquire
* memory order here to synchronize with store-release
* in runstate update functions.
*/
while (__atomic_load_n(&cs->runstate, __ATOMIC_ACQUIRE) ==
RUNSTATE_RUNNING) {
const uint64_t service_mask = cs->service_mask;
for (i = 0; i < RTE_SERVICE_NUM_MAX; i++) {
@ -445,8 +473,6 @@ service_runner_func(void *arg)
}
cs->loops++;
rte_smp_rmb();
}
lcore_config[lcore].state = WAIT;
@ -613,15 +639,18 @@ rte_service_lcore_reset_all(void)
if (lcore_states[i].is_service_core) {
lcore_states[i].service_mask = 0;
set_lcore_state(i, ROLE_RTE);
lcore_states[i].runstate = RUNSTATE_STOPPED;
/* runstate act as guard variable Use
* store-release memory order here to synchronize
* with load-acquire in runstate read functions.
*/
__atomic_store_n(&lcore_states[i].runstate,
RUNSTATE_STOPPED, __ATOMIC_RELEASE);
}
}
for (i = 0; i < RTE_SERVICE_NUM_MAX; i++)
__atomic_store_n(&rte_services[i].num_mapped_cores, 0,
__ATOMIC_RELAXED);
rte_smp_wmb();
return 0;
}
@ -637,9 +666,11 @@ rte_service_lcore_add(uint32_t lcore)
/* ensure that after adding a core the mask and state are defaults */
lcore_states[lcore].service_mask = 0;
lcore_states[lcore].runstate = RUNSTATE_STOPPED;
rte_smp_wmb();
/* Use store-release memory order here to synchronize with
* load-acquire in runstate read functions.
*/
__atomic_store_n(&lcore_states[lcore].runstate, RUNSTATE_STOPPED,
__ATOMIC_RELEASE);
return rte_eal_wait_lcore(lcore);
}
@ -654,7 +685,12 @@ rte_service_lcore_del(uint32_t lcore)
if (!cs->is_service_core)
return -EINVAL;
if (cs->runstate != RUNSTATE_STOPPED)
/* runstate act as the guard variable. Use load-acquire
* memory order here to synchronize with store-release
* in runstate update functions.
*/
if (__atomic_load_n(&cs->runstate, __ATOMIC_ACQUIRE) !=
RUNSTATE_STOPPED)
return -EBUSY;
set_lcore_state(lcore, ROLE_RTE);
@ -673,13 +709,21 @@ rte_service_lcore_start(uint32_t lcore)
if (!cs->is_service_core)
return -EINVAL;
if (cs->runstate == RUNSTATE_RUNNING)
/* runstate act as the guard variable. Use load-acquire
* memory order here to synchronize with store-release
* in runstate update functions.
*/
if (__atomic_load_n(&cs->runstate, __ATOMIC_ACQUIRE) ==
RUNSTATE_RUNNING)
return -EALREADY;
/* set core to run state first, and then launch otherwise it will
* return immediately as runstate keeps it in the service poll loop
*/
cs->runstate = RUNSTATE_RUNNING;
/* Use load-acquire memory order here to synchronize with
* store-release in runstate update functions.
*/
__atomic_store_n(&cs->runstate, RUNSTATE_RUNNING, __ATOMIC_RELEASE);
int ret = rte_eal_remote_launch(service_runner_func, 0, lcore);
/* returns -EBUSY if the core is already launched, 0 on success */
@ -692,7 +736,12 @@ rte_service_lcore_stop(uint32_t lcore)
if (lcore >= RTE_MAX_LCORE)
return -EINVAL;
if (lcore_states[lcore].runstate == RUNSTATE_STOPPED)
/* runstate act as the guard variable. Use load-acquire
* memory order here to synchronize with store-release
* in runstate update functions.
*/
if (__atomic_load_n(&lcore_states[lcore].runstate, __ATOMIC_ACQUIRE) ==
RUNSTATE_STOPPED)
return -EALREADY;
uint32_t i;
@ -712,7 +761,11 @@ rte_service_lcore_stop(uint32_t lcore)
return -EBUSY;
}
lcore_states[lcore].runstate = RUNSTATE_STOPPED;
/* Use store-release memory order here to synchronize with
* load-acquire in runstate read functions.
*/
__atomic_store_n(&lcore_states[lcore].runstate, RUNSTATE_STOPPED,
__ATOMIC_RELEASE);
return 0;
}