power: use C11 atomics for power state

Since rte_atomicXX APIs are not allowed to be used, use C11 atomic
builtins for power in use state update.

Signed-off-by: Phil Yang <phil.yang@arm.com>
Reviewed-by: Ruifeng Wang <ruifeng.wang@arm.com>
Reviewed-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>
Acked-by: David Hunt <david.hunt@intel.com>

diff --git a/lib/librte_power/power_acpi_cpufreq.c b/lib/librte_power/power_acpi_cpufreq.c
index 583815a..84a9d75 100644 (file)
--- a/lib/librte_power/power_acpi_cpufreq.c
+++ b/lib/librte_power/power_acpi_cpufreq.c
@@ -12,7 +12,6 @@
 #include <signal.h>
 #include <limits.h>
 
-#include <rte_atomic.h>
 #include <rte_memcpy.h>
 #include <rte_memory.h>
 #include <rte_string_fns.h>
@@ -86,7 +85,7 @@ struct rte_power_info {
        FILE *f;                             /**< FD of scaling_setspeed */
        char governor_ori[32];               /**< Original governor name */
        uint32_t curr_idx;                   /**< Freq index in freqs array */
-       volatile uint32_t state;             /**< Power in use state */
+       uint32_t state;                      /**< Power in use state */
        uint16_t turbo_available;            /**< Turbo Boost available */
        uint16_t turbo_enable;               /**< Turbo Boost enable/disable */
 } __rte_cache_aligned;
@@ -300,6 +299,7 @@ int
 power_acpi_cpufreq_init(unsigned int lcore_id)
 {
        struct rte_power_info *pi;
+       uint32_t exp_state;
 
        if (lcore_id >= RTE_MAX_LCORE) {
                RTE_LOG(ERR, POWER, "Lcore id %u can not exceeds %u\n",
@@ -308,8 +308,16 @@ power_acpi_cpufreq_init(unsigned int lcore_id)
        }
 
        pi = &lcore_power_info[lcore_id];
-       if (rte_atomic32_cmpset(&(pi->state), POWER_IDLE, POWER_ONGOING)
-                       == 0) {
+       exp_state = POWER_IDLE;
+       /* The power in use state works as a guard variable between
+        * the CPU frequency control initialization and exit process.
+        * The ACQUIRE memory ordering here pairs with the RELEASE
+        * ordering below as lock to make sure the frequency operations
+        * in the critical section are done under the correct state.
+        */
+       if (!__atomic_compare_exchange_n(&(pi->state), &exp_state,
+                                       POWER_ONGOING, 0,
+                                       __ATOMIC_ACQUIRE, __ATOMIC_RELAXED)) {
                RTE_LOG(INFO, POWER, "Power management of lcore %u is "
                                "in use\n", lcore_id);
                return -1;
@@ -346,12 +354,16 @@ power_acpi_cpufreq_init(unsigned int lcore_id)
 
        RTE_LOG(INFO, POWER, "Initialized successfully for lcore %u "
                        "power management\n", lcore_id);
-       rte_atomic32_cmpset(&(pi->state), POWER_ONGOING, POWER_USED);
+       exp_state = POWER_ONGOING;
+       __atomic_compare_exchange_n(&(pi->state), &exp_state, POWER_USED,
+                                   0, __ATOMIC_RELEASE, __ATOMIC_RELAXED);
 
        return 0;
 
 fail:
-       rte_atomic32_cmpset(&(pi->state), POWER_ONGOING, POWER_UNKNOWN);
+       exp_state = POWER_ONGOING;
+       __atomic_compare_exchange_n(&(pi->state), &exp_state, POWER_UNKNOWN,
+                                   0, __ATOMIC_RELEASE, __ATOMIC_RELAXED);
 
        return -1;
 }
@@ -408,6 +420,7 @@ int
 power_acpi_cpufreq_exit(unsigned int lcore_id)
 {
        struct rte_power_info *pi;
+       uint32_t exp_state;
 
        if (lcore_id >= RTE_MAX_LCORE) {
                RTE_LOG(ERR, POWER, "Lcore id %u can not exceeds %u\n",
@@ -415,8 +428,16 @@ power_acpi_cpufreq_exit(unsigned int lcore_id)
                return -1;
        }
        pi = &lcore_power_info[lcore_id];
-       if (rte_atomic32_cmpset(&(pi->state), POWER_USED, POWER_ONGOING)
-                       == 0) {
+       exp_state = POWER_USED;
+       /* The power in use state works as a guard variable between
+        * the CPU frequency control initialization and exit process.
+        * The ACQUIRE memory ordering here pairs with the RELEASE
+        * ordering below as lock to make sure the frequency operations
+        * in the critical section are done under the correct state.
+        */
+       if (!__atomic_compare_exchange_n(&(pi->state), &exp_state,
+                                       POWER_ONGOING, 0,
+                                       __ATOMIC_ACQUIRE, __ATOMIC_RELAXED)) {
                RTE_LOG(INFO, POWER, "Power management of lcore %u is "
                                "not used\n", lcore_id);
                return -1;
@@ -436,12 +457,16 @@ power_acpi_cpufreq_exit(unsigned int lcore_id)
        RTE_LOG(INFO, POWER, "Power management of lcore %u has exited from "
                        "'userspace' mode and been set back to the "
                        "original\n", lcore_id);
-       rte_atomic32_cmpset(&(pi->state), POWER_ONGOING, POWER_IDLE);
+       exp_state = POWER_ONGOING;
+       __atomic_compare_exchange_n(&(pi->state), &exp_state, POWER_IDLE,
+                                   0, __ATOMIC_RELEASE, __ATOMIC_RELAXED);
 
        return 0;
 
 fail:
-       rte_atomic32_cmpset(&(pi->state), POWER_ONGOING, POWER_UNKNOWN);
+       exp_state = POWER_ONGOING;
+       __atomic_compare_exchange_n(&(pi->state), &exp_state, POWER_UNKNOWN,
+                                   0, __ATOMIC_RELEASE, __ATOMIC_RELAXED);
 
        return -1;
 }

diff --git a/lib/librte_power/power_pstate_cpufreq.c b/lib/librte_power/power_pstate_cpufreq.c
index 2526441..e3126d3 100644 (file)
--- a/lib/librte_power/power_pstate_cpufreq.c
+++ b/lib/librte_power/power_pstate_cpufreq.c
@@ -14,7 +14,6 @@
 #include <errno.h>
 #include <inttypes.h>
 
-#include <rte_atomic.h>
 #include <rte_memcpy.h>
 #include <rte_memory.h>
 #include <rte_string_fns.h>
@@ -100,7 +99,7 @@ struct pstate_power_info {
        uint32_t non_turbo_max_ratio;        /**< Non Turbo Max ratio  */
        uint32_t sys_max_freq;               /**< system wide max freq  */
        uint32_t core_base_freq;             /**< core base freq  */
-       volatile uint32_t state;             /**< Power in use state */
+       uint32_t state;                      /**< Power in use state */
        uint16_t turbo_available;            /**< Turbo Boost available */
        uint16_t turbo_enable;               /**< Turbo Boost enable/disable */
        uint16_t priority_core;              /**< High Performance core */
@@ -542,6 +541,7 @@ int
 power_pstate_cpufreq_init(unsigned int lcore_id)
 {
        struct pstate_power_info *pi;
+       uint32_t exp_state;
 
        if (lcore_id >= RTE_MAX_LCORE) {
                RTE_LOG(ERR, POWER, "Lcore id %u can not exceed %u\n",
@@ -550,8 +550,16 @@ power_pstate_cpufreq_init(unsigned int lcore_id)
        }
 
        pi = &lcore_power_info[lcore_id];
-       if (rte_atomic32_cmpset(&(pi->state), POWER_IDLE, POWER_ONGOING)
-                       == 0) {
+       exp_state = POWER_IDLE;
+       /* The power in use state works as a guard variable between
+        * the CPU frequency control initialization and exit process.
+        * The ACQUIRE memory ordering here pairs with the RELEASE
+        * ordering below as lock to make sure the frequency operations
+        * in the critical section are done under the correct state.
+        */
+       if (!__atomic_compare_exchange_n(&(pi->state), &exp_state,
+                                       POWER_ONGOING, 0,
+                                       __ATOMIC_ACQUIRE, __ATOMIC_RELAXED)) {
                RTE_LOG(INFO, POWER, "Power management of lcore %u is "
                                "in use\n", lcore_id);
                return -1;
@@ -588,12 +596,16 @@ power_pstate_cpufreq_init(unsigned int lcore_id)
 
        RTE_LOG(INFO, POWER, "Initialized successfully for lcore %u "
                        "power management\n", lcore_id);
-       rte_atomic32_cmpset(&(pi->state), POWER_ONGOING, POWER_USED);
+       exp_state = POWER_ONGOING;
+       __atomic_compare_exchange_n(&(pi->state), &exp_state, POWER_USED,
+                                   0, __ATOMIC_RELEASE, __ATOMIC_RELAXED);
 
        return 0;
 
 fail:
-       rte_atomic32_cmpset(&(pi->state), POWER_ONGOING, POWER_UNKNOWN);
+       exp_state = POWER_ONGOING;
+       __atomic_compare_exchange_n(&(pi->state), &exp_state, POWER_UNKNOWN,
+                                   0, __ATOMIC_RELEASE, __ATOMIC_RELAXED);
 
        return -1;
 }
@@ -602,6 +614,7 @@ int
 power_pstate_cpufreq_exit(unsigned int lcore_id)
 {
        struct pstate_power_info *pi;
+       uint32_t exp_state;
 
        if (lcore_id >= RTE_MAX_LCORE) {
                RTE_LOG(ERR, POWER, "Lcore id %u can not exceeds %u\n",
@@ -610,8 +623,16 @@ power_pstate_cpufreq_exit(unsigned int lcore_id)
        }
        pi = &lcore_power_info[lcore_id];
 
-       if (rte_atomic32_cmpset(&(pi->state), POWER_USED, POWER_ONGOING)
-                       == 0) {
+       exp_state = POWER_USED;
+       /* The power in use state works as a guard variable between
+        * the CPU frequency control initialization and exit process.
+        * The ACQUIRE memory ordering here pairs with the RELEASE
+        * ordering below as lock to make sure the frequency operations
+        * in the critical section are under done the correct state.
+        */
+       if (!__atomic_compare_exchange_n(&(pi->state), &exp_state,
+                                       POWER_ONGOING, 0,
+                                       __ATOMIC_ACQUIRE, __ATOMIC_RELAXED)) {
                RTE_LOG(INFO, POWER, "Power management of lcore %u is "
                                "not used\n", lcore_id);
                return -1;
@@ -633,12 +654,16 @@ power_pstate_cpufreq_exit(unsigned int lcore_id)
        RTE_LOG(INFO, POWER, "Power management of lcore %u has exited from "
                        "'performance' mode and been set back to the "
                        "original\n", lcore_id);
-       rte_atomic32_cmpset(&(pi->state), POWER_ONGOING, POWER_IDLE);
+       exp_state = POWER_ONGOING;
+       __atomic_compare_exchange_n(&(pi->state), &exp_state, POWER_IDLE,
+                                   0, __ATOMIC_RELEASE, __ATOMIC_RELAXED);
 
        return 0;
 
 fail:
-       rte_atomic32_cmpset(&(pi->state), POWER_ONGOING, POWER_UNKNOWN);
+       exp_state = POWER_ONGOING;
+       __atomic_compare_exchange_n(&(pi->state), &exp_state, POWER_UNKNOWN,
+                                   0, __ATOMIC_RELEASE, __ATOMIC_RELAXED);
 
        return -1;
 }