Now that we have everything in a C file, we can store the information
about our sleep, and have a native mechanism to wake up the sleeping
core. This mechanism would however only wake up a core that's sleeping
while monitoring - waking up from `rte_power_pause` won't work.
Signed-off-by: Anatoly Burakov <anatoly.bura...@intel.com>
---
Notes:
v13:
- Add comments around wakeup code to explain what it does
- Add lcore_id parameter checking to prevent buffer overrun
.../arm/include/rte_power_intrinsics.h | 9 ++
.../include/generic/rte_power_intrinsics.h | 16 ++++
.../ppc/include/rte_power_intrinsics.h | 9 ++
lib/librte_eal/version.map | 1 +
lib/librte_eal/x86/rte_power_intrinsics.c | 85 +++++++++++++++++++
5 files changed, 120 insertions(+)
diff --git a/lib/librte_eal/arm/include/rte_power_intrinsics.h
b/lib/librte_eal/arm/include/rte_power_intrinsics.h
index 27869251a8..39e49cc45b 100644
--- a/lib/librte_eal/arm/include/rte_power_intrinsics.h
+++ b/lib/librte_eal/arm/include/rte_power_intrinsics.h
@@ -33,6 +33,15 @@ rte_power_pause(const uint64_t tsc_timestamp)
RTE_SET_USED(tsc_timestamp);
}
+/**
+ * This function is not supported on ARM.
+ */
+void
+rte_power_monitor_wakeup(const unsigned int lcore_id)
+{
+RTE_SET_USED(lcore_id);
+}
+
#ifdef __cplusplus
}
#endif
diff --git a/lib/librte_eal/include/generic/rte_power_intrinsics.h
b/lib/librte_eal/include/generic/rte_power_intrinsics.h
index a6f1955996..e311d6f8ea 100644
--- a/lib/librte_eal/include/generic/rte_power_intrinsics.h
+++ b/lib/librte_eal/include/generic/rte_power_intrinsics.h
@@ -57,6 +57,22 @@ __rte_experimental
void rte_power_monitor(const struct rte_power_monitor_cond *pmc,
const uint64_t tsc_timestamp);
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change without prior notice
+ *
+ * Wake up a specific lcore that is in a power optimized state and
is monitoring
+ * an address.
+ *
+ * @note This function will *not* wake up a core that is in a power
optimized
+ * state due to calling `rte_power_pause`.
+ *
+ * @param lcore_id
+ * Lcore ID of a sleeping thread.
+ */
+__rte_experimental
+void rte_power_monitor_wakeup(const unsigned int lcore_id);
+
/**
* @warning
* @b EXPERIMENTAL: this API may change without prior notice
diff --git a/lib/librte_eal/ppc/include/rte_power_intrinsics.h
b/lib/librte_eal/ppc/include/rte_power_intrinsics.h
index 248d1f4a23..2e7db0e7eb 100644
--- a/lib/librte_eal/ppc/include/rte_power_intrinsics.h
+++ b/lib/librte_eal/ppc/include/rte_power_intrinsics.h
@@ -33,6 +33,15 @@ rte_power_pause(const uint64_t tsc_timestamp)
RTE_SET_USED(tsc_timestamp);
}
+/**
+ * This function is not supported on PPC64.
+ */
+void
+rte_power_monitor_wakeup(const unsigned int lcore_id)
+{
+RTE_SET_USED(lcore_id);
+}
+
#ifdef __cplusplus
}
#endif
diff --git a/lib/librte_eal/version.map b/lib/librte_eal/version.map
index 20945b1efa..ac026e289d 100644
--- a/lib/librte_eal/version.map
+++ b/lib/librte_eal/version.map
@@ -406,6 +406,7 @@ EXPERIMENTAL {
# added in 21.02
rte_power_monitor;
+rte_power_monitor_wakeup;
rte_power_pause;
};
diff --git a/lib/librte_eal/x86/rte_power_intrinsics.c
b/lib/librte_eal/x86/rte_power_intrinsics.c
index a9cd1afe9d..46a4fb6cd5 100644
--- a/lib/librte_eal/x86/rte_power_intrinsics.c
+++ b/lib/librte_eal/x86/rte_power_intrinsics.c
@@ -2,8 +2,31 @@
* Copyright(c) 2020 Intel Corporation
*/
+#include <rte_common.h>
+#include <rte_lcore.h>
+#include <rte_spinlock.h>
+
#include "rte_power_intrinsics.h"
+/*
+ * Per-lcore structure holding current status of C0.2 sleeps.
+ */
+static struct power_wait_status {
+rte_spinlock_t lock;
+volatile void *monitor_addr; /**< NULL if not currently sleeping */
+} __rte_cache_aligned wait_status[RTE_MAX_LCORE];
+
+static inline void
+__umwait_wakeup(volatile void *addr)
+{
+uint64_t val;
+
+/* trigger a write but don't change the value */
+val = __atomic_load_n((volatile uint64_t *)addr, __ATOMIC_RELAXED);
+__atomic_compare_exchange_n((volatile uint64_t *)addr, &val, val, 0,
+__ATOMIC_RELAXED, __ATOMIC_RELAXED);
+}
+
static uint8_t wait_supported;
static inline uint64_t
@@ -36,6 +59,12 @@ rte_power_monitor(const struct
rte_power_monitor_cond *pmc,
{
const uint32_t tsc_l = (uint32_t)tsc_timestamp;
const uint32_t tsc_h = (uint32_t)(tsc_timestamp >> 32);
+const unsigned int lcore_id = rte_lcore_id();
+struct power_wait_status *s;
+
+/* prevent non-EAL thread from using this API */
+if (lcore_id >= RTE_MAX_LCORE)
+return;
/* prevent user from running this instruction if it's not supported */
if (!wait_supported)
@@ -60,11 +89,24 @@ rte_power_monitor(const struct
rte_power_monitor_cond *pmc,
if (masked == pmc->val)
return;
}
+
+s = &wait_status[lcore_id];
+
+/* update sleep address */
+rte_spinlock_lock(&s->lock);
+s->monitor_addr = pmc->addr;
+rte_spinlock_unlock(&s->lock);