[dpdk-dev] [PATCH v7 1/7] power_intrinsics: use callbacks for comparison

[Anatoly Burakov <anatoly.burakov@intel.com>]

Previously, the semantics of power monitor were such that we were
checking current value against the expected value, and if they matched,
then the sleep was aborted. This is somewhat inflexible, because it only
allowed us to check for a specific value in a specific way.

This commit replaces the comparison with a user callback mechanism, so
that any PMD (or other code) using `rte_power_monitor()` can define
their own comparison semantics and decision making on how to detect the
need to abort the entering of power optimized state.

Existing implementations are adjusted to follow the new semantics.

Suggested-by: Konstantin Ananyev <konstantin.ananyev@intel.com>
Signed-off-by: Anatoly Burakov <anatoly.burakov@intel.com>
Acked-by: Konstantin Ananyev <konstantin.ananyev@intel.com>
---

Notes:
    v4:
    - Return error if callback is set to NULL
    - Replace raw number with a macro in monitor condition opaque data
    
    v2:
    - Use callback mechanism for more flexibility
    - Address feedback from Konstantin

 doc/guides/rel_notes/release_21_08.rst        |  2 ++
 drivers/event/dlb2/dlb2.c                     | 17 ++++++++--
 drivers/net/i40e/i40e_rxtx.c                  | 20 +++++++----
 drivers/net/iavf/iavf_rxtx.c                  | 20 +++++++----
 drivers/net/ice/ice_rxtx.c                    | 20 +++++++----
 drivers/net/ixgbe/ixgbe_rxtx.c                | 20 +++++++----
 drivers/net/mlx5/mlx5_rx.c                    | 17 ++++++++--
 .../include/generic/rte_power_intrinsics.h    | 33 +++++++++++++++----
 lib/eal/x86/rte_power_intrinsics.c            | 17 +++++-----
 9 files changed, 122 insertions(+), 44 deletions(-)

diff --git a/doc/guides/rel_notes/release_21_08.rst b/doc/guides/rel_notes/release_21_08.rst
index cd02820e68..c1d063bb11 100644
--- a/doc/guides/rel_notes/release_21_08.rst
+++ b/doc/guides/rel_notes/release_21_08.rst
@@ -117,6 +117,8 @@ API Changes
 * eal: ``rte_strscpy`` sets ``rte_errno`` to ``E2BIG`` in case of string
   truncation.
 
+* eal: the ``rte_power_intrinsics`` API changed to use a callback mechanism.
+
 
 ABI Changes
 -----------
diff --git a/drivers/event/dlb2/dlb2.c b/drivers/event/dlb2/dlb2.c
index eca183753f..252bbd8d5e 100644
--- a/drivers/event/dlb2/dlb2.c
+++ b/drivers/event/dlb2/dlb2.c
@@ -3154,6 +3154,16 @@ dlb2_port_credits_inc(struct dlb2_port *qm_port, int num)
 	}
 }
 
+#define CLB_MASK_IDX 0
+#define CLB_VAL_IDX 1
+static int
+dlb2_monitor_callback(const uint64_t val,
+		const uint64_t opaque[RTE_POWER_MONITOR_OPAQUE_SZ])
+{
+	/* abort if the value matches */
+	return (val & opaque[CLB_MASK_IDX]) == opaque[CLB_VAL_IDX] ? -1 : 0;
+}
+
 static inline int
 dlb2_dequeue_wait(struct dlb2_eventdev *dlb2,
 		  struct dlb2_eventdev_port *ev_port,
@@ -3194,8 +3204,11 @@ dlb2_dequeue_wait(struct dlb2_eventdev *dlb2,
 			expected_value = 0;
 
 		pmc.addr = monitor_addr;
-		pmc.val = expected_value;
-		pmc.mask = qe_mask.raw_qe[1];
+		/* store expected value and comparison mask in opaque data */
+		pmc.opaque[CLB_VAL_IDX] = expected_value;
+		pmc.opaque[CLB_MASK_IDX] = qe_mask.raw_qe[1];
+		/* set up callback */
+		pmc.fn = dlb2_monitor_callback;
 		pmc.size = sizeof(uint64_t);
 
 		rte_power_monitor(&pmc, timeout + start_ticks);
diff --git a/drivers/net/i40e/i40e_rxtx.c b/drivers/net/i40e/i40e_rxtx.c
index 8d65f287f4..65f325ede1 100644
--- a/drivers/net/i40e/i40e_rxtx.c
+++ b/drivers/net/i40e/i40e_rxtx.c
@@ -81,6 +81,18 @@
 #define I40E_TX_OFFLOAD_SIMPLE_NOTSUP_MASK \
 		(PKT_TX_OFFLOAD_MASK ^ I40E_TX_OFFLOAD_SIMPLE_SUP_MASK)
 
+static int
+i40e_monitor_callback(const uint64_t value,
+		const uint64_t arg[RTE_POWER_MONITOR_OPAQUE_SZ] __rte_unused)
+{
+	const uint64_t m = rte_cpu_to_le_64(1 << I40E_RX_DESC_STATUS_DD_SHIFT);
+	/*
+	 * we expect the DD bit to be set to 1 if this descriptor was already
+	 * written to.
+	 */
+	return (value & m) == m ? -1 : 0;
+}
+
 int
 i40e_get_monitor_addr(void *rx_queue, struct rte_power_monitor_cond *pmc)
 {
@@ -93,12 +105,8 @@ i40e_get_monitor_addr(void *rx_queue, struct rte_power_monitor_cond *pmc)
 	/* watch for changes in status bit */
 	pmc->addr = &rxdp->wb.qword1.status_error_len;
 
-	/*
-	 * we expect the DD bit to be set to 1 if this descriptor was already
-	 * written to.
-	 */
-	pmc->val = rte_cpu_to_le_64(1 << I40E_RX_DESC_STATUS_DD_SHIFT);
-	pmc->mask = rte_cpu_to_le_64(1 << I40E_RX_DESC_STATUS_DD_SHIFT);
+	/* comparison callback */
+	pmc->fn = i40e_monitor_callback;
 
 	/* registers are 64-bit */
 	pmc->size = sizeof(uint64_t);
diff --git a/drivers/net/iavf/iavf_rxtx.c b/drivers/net/iavf/iavf_rxtx.c
index f817fbc49b..d61b32fcee 100644
--- a/drivers/net/iavf/iavf_rxtx.c
+++ b/drivers/net/iavf/iavf_rxtx.c
@@ -57,6 +57,18 @@ iavf_proto_xtr_type_to_rxdid(uint8_t flex_type)
 				rxdid_map[flex_type] : IAVF_RXDID_COMMS_OVS_1;
 }
 
+static int
+iavf_monitor_callback(const uint64_t value,
+		const uint64_t arg[RTE_POWER_MONITOR_OPAQUE_SZ] __rte_unused)
+{
+	const uint64_t m = rte_cpu_to_le_64(1 << IAVF_RX_DESC_STATUS_DD_SHIFT);
+	/*
+	 * we expect the DD bit to be set to 1 if this descriptor was already
+	 * written to.
+	 */
+	return (value & m) == m ? -1 : 0;
+}
+
 int
 iavf_get_monitor_addr(void *rx_queue, struct rte_power_monitor_cond *pmc)
 {
@@ -69,12 +81,8 @@ iavf_get_monitor_addr(void *rx_queue, struct rte_power_monitor_cond *pmc)
 	/* watch for changes in status bit */
 	pmc->addr = &rxdp->wb.qword1.status_error_len;
 
-	/*
-	 * we expect the DD bit to be set to 1 if this descriptor was already
-	 * written to.
-	 */
-	pmc->val = rte_cpu_to_le_64(1 << IAVF_RX_DESC_STATUS_DD_SHIFT);
-	pmc->mask = rte_cpu_to_le_64(1 << IAVF_RX_DESC_STATUS_DD_SHIFT);
+	/* comparison callback */
+	pmc->fn = iavf_monitor_callback;
 
 	/* registers are 64-bit */
 	pmc->size = sizeof(uint64_t);
diff --git a/drivers/net/ice/ice_rxtx.c b/drivers/net/ice/ice_rxtx.c
index 3f6e735984..5d7ab4f047 100644
--- a/drivers/net/ice/ice_rxtx.c
+++ b/drivers/net/ice/ice_rxtx.c
@@ -27,6 +27,18 @@ uint64_t rte_net_ice_dynflag_proto_xtr_ipv6_flow_mask;
 uint64_t rte_net_ice_dynflag_proto_xtr_tcp_mask;
 uint64_t rte_net_ice_dynflag_proto_xtr_ip_offset_mask;
 
+static int
+ice_monitor_callback(const uint64_t value,
+		const uint64_t arg[RTE_POWER_MONITOR_OPAQUE_SZ] __rte_unused)
+{
+	const uint64_t m = rte_cpu_to_le_16(1 << ICE_RX_FLEX_DESC_STATUS0_DD_S);
+	/*
+	 * we expect the DD bit to be set to 1 if this descriptor was already
+	 * written to.
+	 */
+	return (value & m) == m ? -1 : 0;
+}
+
 int
 ice_get_monitor_addr(void *rx_queue, struct rte_power_monitor_cond *pmc)
 {
@@ -39,12 +51,8 @@ ice_get_monitor_addr(void *rx_queue, struct rte_power_monitor_cond *pmc)
 	/* watch for changes in status bit */
 	pmc->addr = &rxdp->wb.status_error0;
 
-	/*
-	 * we expect the DD bit to be set to 1 if this descriptor was already
-	 * written to.
-	 */
-	pmc->val = rte_cpu_to_le_16(1 << ICE_RX_FLEX_DESC_STATUS0_DD_S);
-	pmc->mask = rte_cpu_to_le_16(1 << ICE_RX_FLEX_DESC_STATUS0_DD_S);
+	/* comparison callback */
+	pmc->fn = ice_monitor_callback;
 
 	/* register is 16-bit */
 	pmc->size = sizeof(uint16_t);
diff --git a/drivers/net/ixgbe/ixgbe_rxtx.c b/drivers/net/ixgbe/ixgbe_rxtx.c
index d69f36e977..c814a28cb4 100644
--- a/drivers/net/ixgbe/ixgbe_rxtx.c
+++ b/drivers/net/ixgbe/ixgbe_rxtx.c
@@ -1369,6 +1369,18 @@ const uint32_t
 		RTE_PTYPE_INNER_L3_IPV4_EXT | RTE_PTYPE_INNER_L4_UDP,
 };
 
+static int
+ixgbe_monitor_callback(const uint64_t value,
+		const uint64_t arg[RTE_POWER_MONITOR_OPAQUE_SZ] __rte_unused)
+{
+	const uint64_t m = rte_cpu_to_le_32(IXGBE_RXDADV_STAT_DD);
+	/*
+	 * we expect the DD bit to be set to 1 if this descriptor was already
+	 * written to.
+	 */
+	return (value & m) == m ? -1 : 0;
+}
+
 int
 ixgbe_get_monitor_addr(void *rx_queue, struct rte_power_monitor_cond *pmc)
 {
@@ -1381,12 +1393,8 @@ ixgbe_get_monitor_addr(void *rx_queue, struct rte_power_monitor_cond *pmc)
 	/* watch for changes in status bit */
 	pmc->addr = &rxdp->wb.upper.status_error;
 
-	/*
-	 * we expect the DD bit to be set to 1 if this descriptor was already
-	 * written to.
-	 */
-	pmc->val = rte_cpu_to_le_32(IXGBE_RXDADV_STAT_DD);
-	pmc->mask = rte_cpu_to_le_32(IXGBE_RXDADV_STAT_DD);
+	/* comparison callback */
+	pmc->fn = ixgbe_monitor_callback;
 
 	/* the registers are 32-bit */
 	pmc->size = sizeof(uint32_t);
diff --git a/drivers/net/mlx5/mlx5_rx.c b/drivers/net/mlx5/mlx5_rx.c
index 777a1d6e45..17370b77dc 100644
--- a/drivers/net/mlx5/mlx5_rx.c
+++ b/drivers/net/mlx5/mlx5_rx.c
@@ -269,6 +269,18 @@ mlx5_rx_queue_count(struct rte_eth_dev *dev, uint16_t rx_queue_id)
 	return rx_queue_count(rxq);
 }
 
+#define CLB_VAL_IDX 0
+#define CLB_MSK_IDX 1
+static int
+mlx_monitor_callback(const uint64_t value,
+		const uint64_t opaque[RTE_POWER_MONITOR_OPAQUE_SZ])
+{
+	const uint64_t m = opaque[CLB_MSK_IDX];
+	const uint64_t v = opaque[CLB_VAL_IDX];
+
+	return (value & m) == v ? -1 : 0;
+}
+
 int mlx5_get_monitor_addr(void *rx_queue, struct rte_power_monitor_cond *pmc)
 {
 	struct mlx5_rxq_data *rxq = rx_queue;
@@ -282,8 +294,9 @@ int mlx5_get_monitor_addr(void *rx_queue, struct rte_power_monitor_cond *pmc)
 		return -rte_errno;
 	}
 	pmc->addr = &cqe->op_own;
-	pmc->val =  !!idx;
-	pmc->mask = MLX5_CQE_OWNER_MASK;
+	pmc->opaque[CLB_VAL_IDX] = !!idx;
+	pmc->opaque[CLB_MSK_IDX] = MLX5_CQE_OWNER_MASK;
+	pmc->fn = mlx_monitor_callback;
 	pmc->size = sizeof(uint8_t);
 	return 0;
 }
diff --git a/lib/eal/include/generic/rte_power_intrinsics.h b/lib/eal/include/generic/rte_power_intrinsics.h
index dddca3d41c..c9aa52a86d 100644
--- a/lib/eal/include/generic/rte_power_intrinsics.h
+++ b/lib/eal/include/generic/rte_power_intrinsics.h
@@ -18,19 +18,38 @@
  * which are architecture-dependent.
  */
 
+/** Size of the opaque data in monitor condition */
+#define RTE_POWER_MONITOR_OPAQUE_SZ 4
+
+/**
+ * Callback definition for monitoring conditions. Callbacks with this signature
+ * will be used by `rte_power_monitor()` to check if the entering of power
+ * optimized state should be aborted.
+ *
+ * @param val
+ *   The value read from memory.
+ * @param opaque
+ *   Callback-specific data.
+ *
+ * @return
+ *   0 if entering of power optimized state should proceed
+ *   -1 if entering of power optimized state should be aborted
+ */
+typedef int (*rte_power_monitor_clb_t)(const uint64_t val,
+		const uint64_t opaque[RTE_POWER_MONITOR_OPAQUE_SZ]);
 struct rte_power_monitor_cond {
 	volatile void *addr;  /**< Address to monitor for changes */
-	uint64_t val;         /**< If the `mask` is non-zero, location pointed
-	                       *   to by `addr` will be read and compared
-	                       *   against this value.
-	                       */
-	uint64_t mask;   /**< 64-bit mask to extract value read from `addr` */
-	uint8_t size;    /**< Data size (in bytes) that will be used to compare
-	                  *   expected value (`val`) with data read from the
+	uint8_t size;    /**< Data size (in bytes) that will be read from the
 	                  *   monitored memory location (`addr`). Can be 1, 2,
 	                  *   4, or 8. Supplying any other value will result in
 	                  *   an error.
 	                  */
+	rte_power_monitor_clb_t fn; /**< Callback to be used to check if
+	                             *   entering power optimized state should
+	                             *   be aborted.
+	                             */
+	uint64_t opaque[RTE_POWER_MONITOR_OPAQUE_SZ];
+	/**< Callback-specific data */
 };
 
 /**
diff --git a/lib/eal/x86/rte_power_intrinsics.c b/lib/eal/x86/rte_power_intrinsics.c
index 39ea9fdecd..66fea28897 100644
--- a/lib/eal/x86/rte_power_intrinsics.c
+++ b/lib/eal/x86/rte_power_intrinsics.c
@@ -76,6 +76,7 @@ rte_power_monitor(const struct rte_power_monitor_cond *pmc,
 	const uint32_t tsc_h = (uint32_t)(tsc_timestamp >> 32);
 	const unsigned int lcore_id = rte_lcore_id();
 	struct power_wait_status *s;
+	uint64_t cur_value;
 
 	/* prevent user from running this instruction if it's not supported */
 	if (!wait_supported)
@@ -91,6 +92,9 @@ rte_power_monitor(const struct rte_power_monitor_cond *pmc,
 	if (__check_val_size(pmc->size) < 0)
 		return -EINVAL;
 
+	if (pmc->fn == NULL)
+		return -EINVAL;
+
 	s = &wait_status[lcore_id];
 
 	/* update sleep address */
@@ -110,16 +114,11 @@ rte_power_monitor(const struct rte_power_monitor_cond *pmc,
 	/* now that we've put this address into monitor, we can unlock */
 	rte_spinlock_unlock(&s->lock);
 
-	/* if we have a comparison mask, we might not need to sleep at all */
-	if (pmc->mask) {
-		const uint64_t cur_value = __get_umwait_val(
-				pmc->addr, pmc->size);
-		const uint64_t masked = cur_value & pmc->mask;
+	cur_value = __get_umwait_val(pmc->addr, pmc->size);
 
-		/* if the masked value is already matching, abort */
-		if (masked == pmc->val)
-			goto end;
-	}
+	/* check if callback indicates we should abort */
+	if (pmc->fn(cur_value, pmc->opaque) != 0)
+		goto end;
 
 	/* execute UMWAIT */
 	asm volatile(".byte 0xf2, 0x0f, 0xae, 0xf7;"
-- 
2.25.1