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event/dsw: avoid migration waves in large systems

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DSW limits the rate of migrations on a per-port basis. Hence, as the
number of cores grows, so does the total migration capacity.

In high core-count systems, this allows for a situation where flows
are migrated to a lightly loaded port which recently already received
a number of new flows (from other ports). The processing load
generated by these new flows may not yet be reflected in the lightly
loaded port's load estimate. The result is that the previously lightly
loaded port is now overloaded.

This patch adds a rough estimate of the size of the inbound migrations
to a particular port, which can be factored into the migration logic,
avoiding the above problem.

Signed-off-by: Mattias Rönnblom <mattias.ronnblom@ericsson.com>
This commit is contained in:
Mattias Rönnblom 2020-03-09 07:51:03 +01:00 committed by Jerin Jacob
parent 1f2b99e8d9
commit 570ac17b8c
3 changed files with 19 additions and 2 deletions
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1
drivers/event/dsw/dsw_evdev.c
View File

@ -62,6 +62,7 @@ dsw_port_setup(struct rte_eventdev *dev, uint8_t port_id,
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;

2
drivers/event/dsw/dsw_evdev.h
View File

@ -220,6 +220,8 @@ struct dsw_port {
/* Estimate of current port load. */
rte_atomic16_t load __rte_cache_aligned;
/* Estimate of flows currently migrating to this port. */
rte_atomic32_t immigration_load __rte_cache_aligned;
} __rte_cache_aligned;
struct dsw_queue {

18
drivers/event/dsw/dsw_event.c
View File

@ -160,6 +160,11 @@ dsw_port_load_update(struct dsw_port *port, uint64_t now)
(DSW_OLD_LOAD_WEIGHT+1);
rte_atomic16_set(&port->load, new_load);
/* The load of the recently immigrated flows should hopefully
* be reflected the load estimate by now.
*/
rte_atomic32_set(&port->immigration_load, 0);
}
static void
@ -362,7 +367,13 @@ 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 load = rte_atomic16_read(&dsw->ports[i].load);
int16_t measured_load = rte_atomic16_read(&dsw->ports[i].load);
int32_t immigration_load =
rte_atomic32_read(&dsw->ports[i].immigration_load);
int32_t load = measured_load + immigration_load;
load = RTE_MIN(load, DSW_MAX_LOAD);
if (load < load_limit)
below_limit = true;
port_loads[i] = load;
@ -491,6 +502,9 @@ 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);
return true;
}
@ -503,7 +517,7 @@ dsw_select_emigration_targets(struct dsw_evdev *dsw,
struct dsw_queue_flow *target_qfs = source_port->emigration_target_qfs;
uint8_t *target_port_ids = source_port->emigration_target_port_ids;
uint8_t *targets_len = &source_port->emigration_targets_len;
uint8_t i;
uint16_t i;
for (i = 0; i < DSW_MAX_FLOWS_PER_MIGRATION; i++) {
bool found;