[dpdk-dev] [PATCH] event/dsw: use GCC built-ins for atomics

["Mattias Rönnblom" <mattias.ronnblom@ericsson.com>]

Use C11-style GCC built-in functions for atomic operations.

Signed-off-by: Mattias Rönnblom <mattias.ronnblom@ericsson.com>
---
 drivers/event/dsw/dsw_evdev.c  |  5 +----
 drivers/event/dsw/dsw_evdev.h  |  6 +++---
 drivers/event/dsw/dsw_event.c  | 37 ++++++++++++++++++++--------------
 drivers/event/dsw/dsw_xstats.c |  4 ++--
 4 files changed, 28 insertions(+), 24 deletions(-)

diff --git a/drivers/event/dsw/dsw_evdev.c b/drivers/event/dsw/dsw_evdev.c
index 933a5a559b..455e8b9027 100644
--- a/drivers/event/dsw/dsw_evdev.c
+++ b/drivers/event/dsw/dsw_evdev.c
@@ -61,9 +61,6 @@ dsw_port_setup(struct rte_eventdev *dev, uint8_t port_id,
 	port->in_ring = in_ring;
 	port->ctl_in_ring = ctl_in_ring;
 
-	rte_atomic16_init(&port->load);
-	rte_atomic32_init(&port->immigration_load);
-
 	port->load_update_interval =
 		(DSW_LOAD_UPDATE_INTERVAL * rte_get_timer_hz()) / US_PER_S;
 
@@ -275,7 +272,7 @@ dsw_start(struct rte_eventdev *dev)
 	uint16_t i;
 	uint64_t now;
 
-	rte_atomic32_init(&dsw->credits_on_loan);
+	dsw->credits_on_loan = 0;
 
 	initial_flow_to_port_assignment(dsw);
 
diff --git a/drivers/event/dsw/dsw_evdev.h b/drivers/event/dsw/dsw_evdev.h
index 6cb77cfc44..08889a0990 100644
--- a/drivers/event/dsw/dsw_evdev.h
+++ b/drivers/event/dsw/dsw_evdev.h
@@ -219,9 +219,9 @@ struct dsw_port {
 	struct rte_ring *ctl_in_ring __rte_cache_aligned;
 
 	/* Estimate of current port load. */
-	rte_atomic16_t load __rte_cache_aligned;
+	int16_t load __rte_cache_aligned;
 	/* Estimate of flows currently migrating to this port. */
-	rte_atomic32_t immigration_load __rte_cache_aligned;
+	int32_t immigration_load __rte_cache_aligned;
 } __rte_cache_aligned;
 
 struct dsw_queue {
@@ -241,7 +241,7 @@ struct dsw_evdev {
 	uint8_t num_queues;
 	int32_t max_inflight;
 
-	rte_atomic32_t credits_on_loan __rte_cache_aligned;
+	int32_t credits_on_loan __rte_cache_aligned;
 };
 
 #define DSW_CTL_PAUS_REQ (0)
diff --git a/drivers/event/dsw/dsw_event.c b/drivers/event/dsw/dsw_event.c
index 611b36781f..1f09816945 100644
--- a/drivers/event/dsw/dsw_event.c
+++ b/drivers/event/dsw/dsw_event.c
@@ -11,7 +11,6 @@
 #include <stdbool.h>
 #include <string.h>
 
-#include <rte_atomic.h>
 #include <rte_cycles.h>
 #include <rte_memcpy.h>
 #include <rte_random.h>
@@ -32,7 +31,8 @@ dsw_port_acquire_credits(struct dsw_evdev *dsw, struct dsw_port *port,
 		return true;
 	}
 
-	total_on_loan = rte_atomic32_read(&dsw->credits_on_loan);
+	total_on_loan =
+		__atomic_load_n(&dsw->credits_on_loan, __ATOMIC_RELAXED);
 	available = dsw->max_inflight - total_on_loan;
 	acquired_credits = RTE_MAX(missing_credits, DSW_PORT_MIN_CREDITS);
 
@@ -43,12 +43,14 @@ dsw_port_acquire_credits(struct dsw_evdev *dsw, struct dsw_port *port,
 	 * thread can allocate tokens in between the check and the
 	 * allocation.
 	 */
-	new_total_on_loan = rte_atomic32_add_return(&dsw->credits_on_loan,
-						    acquired_credits);
+	new_total_on_loan =
+	    __atomic_add_fetch(&dsw->credits_on_loan, acquired_credits,
+			       __ATOMIC_RELAXED);
 
 	if (unlikely(new_total_on_loan > dsw->max_inflight)) {
 		/* Some other port took the last credits */
-		rte_atomic32_sub(&dsw->credits_on_loan, acquired_credits);
+		__atomic_sub_fetch(&dsw->credits_on_loan, acquired_credits,
+				   __ATOMIC_RELAXED);
 		return false;
 	}
 
@@ -74,7 +76,8 @@ dsw_port_return_credits(struct dsw_evdev *dsw, struct dsw_port *port,
 
 		port->inflight_credits = leave_credits;
 
-		rte_atomic32_sub(&dsw->credits_on_loan, return_credits);
+		__atomic_sub_fetch(&dsw->credits_on_loan, return_credits,
+				   __ATOMIC_RELAXED);
 
 		DSW_LOG_DP_PORT(DEBUG, port->id,
 				"Returned %d tokens to pool.\n",
@@ -152,19 +155,19 @@ dsw_port_load_update(struct dsw_port *port, uint64_t now)
 	int16_t period_load;
 	int16_t new_load;
 
-	old_load = rte_atomic16_read(&port->load);
+	old_load = __atomic_load_n(&port->load, __ATOMIC_RELAXED);
 
 	period_load = dsw_port_load_close_period(port, now);
 
 	new_load = (period_load + old_load*DSW_OLD_LOAD_WEIGHT) /
 		(DSW_OLD_LOAD_WEIGHT+1);
 
-	rte_atomic16_set(&port->load, new_load);
+	__atomic_store_n(&port->load, new_load, __ATOMIC_RELAXED);
 
 	/* The load of the recently immigrated flows should hopefully
 	 * be reflected the load estimate by now.
 	 */
-	rte_atomic32_set(&port->immigration_load, 0);
+	__atomic_store_n(&port->immigration_load, 0, __ATOMIC_RELAXED);
 }
 
 static void
@@ -367,9 +370,11 @@ dsw_retrieve_port_loads(struct dsw_evdev *dsw, int16_t *port_loads,
 	uint16_t i;
 
 	for (i = 0; i < dsw->num_ports; i++) {
-		int16_t measured_load = rte_atomic16_read(&dsw->ports[i].load);
+		int16_t measured_load =
+			__atomic_load_n(&dsw->ports[i].load, __ATOMIC_RELAXED);
 		int32_t immigration_load =
-			rte_atomic32_read(&dsw->ports[i].immigration_load);
+			__atomic_load_n(&dsw->ports[i].immigration_load,
+					__ATOMIC_RELAXED);
 		int32_t load = measured_load + immigration_load;
 
 		load = RTE_MIN(load, DSW_MAX_LOAD);
@@ -502,8 +507,8 @@ dsw_select_emigration_target(struct dsw_evdev *dsw,
 	target_qfs[*targets_len] = *candidate_qf;
 	(*targets_len)++;
 
-	rte_atomic32_add(&dsw->ports[candidate_port_id].immigration_load,
-			 candidate_flow_load);
+	__atomic_add_fetch(&dsw->ports[candidate_port_id].immigration_load,
+			   candidate_flow_load, __ATOMIC_RELAXED);
 
 	return true;
 }
@@ -850,7 +855,8 @@ dsw_port_consider_emigration(struct dsw_evdev *dsw,
 		return;
 	}
 
-	source_port_load = rte_atomic16_read(&source_port->load);
+	source_port_load =
+		__atomic_load_n(&source_port->load, __ATOMIC_RELAXED);
 	if (source_port_load < DSW_MIN_SOURCE_LOAD_FOR_MIGRATION) {
 		DSW_LOG_DP_PORT(DEBUG, source_port->id,
 		      "Load %d is below threshold level %d.\n",
@@ -1205,7 +1211,8 @@ dsw_event_enqueue_burst_generic(struct dsw_port *source_port,
 	 * simplicity reasons, we deny the whole burst if the port is
 	 * above the water mark.
 	 */
-	if (unlikely(num_new > 0 && rte_atomic32_read(&dsw->credits_on_loan) >
+	if (unlikely(num_new > 0 &&
+		     __atomic_load_n(&dsw->credits_on_loan, __ATOMIC_RELAXED) >
 		     source_port->new_event_threshold))
 		return 0;
 
diff --git a/drivers/event/dsw/dsw_xstats.c b/drivers/event/dsw/dsw_xstats.c
index e8e92183e2..4f7d4e3ff9 100644
--- a/drivers/event/dsw/dsw_xstats.c
+++ b/drivers/event/dsw/dsw_xstats.c
@@ -48,7 +48,7 @@ struct dsw_xstats_port {
 static uint64_t
 dsw_xstats_dev_credits_on_loan(struct dsw_evdev *dsw)
 {
-	return rte_atomic32_read(&dsw->credits_on_loan);
+	return __atomic_load_n(&dsw->credits_on_loan, __ATOMIC_RELAXED);
 }
 
 static struct dsw_xstat_dev dsw_dev_xstats[] = {
@@ -126,7 +126,7 @@ dsw_xstats_port_get_load(struct dsw_evdev *dsw, uint8_t port_id,
 {
 	int16_t load;
 
-	load = rte_atomic16_read(&dsw->ports[port_id].load);
+	load = __atomic_load_n(&dsw->ports[port_id].load, __ATOMIC_RELAXED);
 
 	return DSW_LOAD_TO_PERCENT(load);
 }
-- 
2.25.1