Neither 'enable_megaflows', 'udpif->flow_limit', 'udpif->n_flows', nor
'udpif->n_flows_timestamp' are used to synchronize the state of any
other variables, so we can use relaxed atomic operations to access
them.
Move the atomic read operation of 'enable_megaflows' outside the loop
in handle_upcalls().
Signed-off-by: Jarno Rajahalme <jrajaha...@nicira.com>
---
ofproto/ofproto-dpif-upcall.c | 42 ++++++++++++++++++++++-------------------
1 file changed, 23 insertions(+), 19 deletions(-)
diff --git a/ofproto/ofproto-dpif-upcall.c b/ofproto/ofproto-dpif-upcall.c
index 5f1d6d5..acf8b6c 100644
--- a/ofproto/ofproto-dpif-upcall.c
+++ b/ofproto/ofproto-dpif-upcall.c
@@ -126,7 +126,7 @@ struct udpif {
atomic_uint flow_limit; /* Datapath flow hard limit. */
/* n_flows_mutex prevents multiple threads updating these concurrently. */
- atomic_ulong n_flows; /* Number of flows in the datapath. */
+ atomic_uint n_flows; /* Number of flows in the datapath. */
atomic_llong n_flows_timestamp; /* Last time n_flows was updated. */
struct ovs_mutex n_flows_mutex;
@@ -533,17 +533,17 @@ udpif_get_n_flows(struct udpif *udpif)
unsigned long flow_count;
now = time_msec();
- atomic_read(&udpif->n_flows_timestamp, &time);
+ atomic_read_relaxed(&udpif->n_flows_timestamp, &time);
if (time < now - 100 && !ovs_mutex_trylock(&udpif->n_flows_mutex)) {
struct dpif_dp_stats stats;
- atomic_store(&udpif->n_flows_timestamp, now);
+ atomic_store_relaxed(&udpif->n_flows_timestamp, now);
dpif_get_dp_stats(udpif->dpif, &stats);
flow_count = stats.n_flows;
- atomic_store(&udpif->n_flows, flow_count);
+ atomic_store_relaxed(&udpif->n_flows, flow_count);
ovs_mutex_unlock(&udpif->n_flows_mutex);
} else {
- atomic_read(&udpif->n_flows, &flow_count);
+ atomic_read_relaxed(&udpif->n_flows, &flow_count);
}
return flow_count;
}
@@ -666,7 +666,6 @@ udpif_revalidator(void *arg)
/* Used only by the leader. */
long long int start_time = 0;
uint64_t last_reval_seq = 0;
- unsigned int flow_limit = 0;
size_t n_flows = 0;
revalidator->id = ovsthread_id_self();
@@ -708,13 +707,15 @@ udpif_revalidator(void *arg)
ovs_barrier_block(&udpif->reval_barrier);
if (leader) {
+ unsigned int flow_limit;
long long int duration;
+ atomic_read_relaxed(&udpif->flow_limit, &flow_limit);
+
dpif_flow_dump_destroy(udpif->dump);
seq_change(udpif->dump_seq);
duration = MAX(time_msec() - start_time, 1);
- atomic_read(&udpif->flow_limit, &flow_limit);
udpif->dump_duration = duration;
if (duration > 2000) {
flow_limit /= duration / 1000;
@@ -725,7 +726,7 @@ udpif_revalidator(void *arg)
flow_limit += 1000;
}
flow_limit = MIN(ofproto_flow_limit, MAX(flow_limit, 1000));
- atomic_store(&udpif->flow_limit, flow_limit);
+ atomic_store_relaxed(&udpif->flow_limit, flow_limit);
if (duration > 2000) {
VLOG_INFO("Spent an unreasonably long %lldms dumping flows",
@@ -939,6 +940,9 @@ upcall_cb(const struct ofpbuf *packet, const struct flow
*flow,
bool megaflow;
int error;
+ atomic_read_relaxed(&enable_megaflows, &megaflow);
+ atomic_read_relaxed(&udpif->flow_limit, &flow_limit);
+
error = upcall_receive(&upcall, udpif->backer, packet, type, userdata,
flow);
if (error) {
@@ -955,8 +959,7 @@ upcall_cb(const struct ofpbuf *packet, const struct flow
*flow,
ofpbuf_size(&upcall.put_actions));
}
- if (wc) {
- atomic_read(&enable_megaflows, &megaflow);
+ if (OVS_LIKELY(wc)) {
if (megaflow) {
/* XXX: This could be avoided with sufficient API changes. */
*wc = upcall.xout.wc;
@@ -966,7 +969,6 @@ upcall_cb(const struct ofpbuf *packet, const struct flow
*flow,
}
}
- atomic_read(&udpif->flow_limit, &flow_limit);
if (udpif_get_n_flows(udpif) >= flow_limit) {
error = ENOSPC;
}
@@ -1055,8 +1057,11 @@ handle_upcalls(struct udpif *udpif, struct upcall
*upcalls,
unsigned int flow_limit;
size_t n_ops, i;
bool may_put;
+ bool megaflow;
+
+ atomic_read_relaxed(&udpif->flow_limit, &flow_limit);
+ atomic_read_relaxed(&enable_megaflows, &megaflow);
- atomic_read(&udpif->flow_limit, &flow_limit);
may_put = udpif_get_n_flows(udpif) < flow_limit;
/* Handle the packets individually in order of arrival.
@@ -1098,10 +1103,9 @@ handle_upcalls(struct udpif *udpif, struct upcall
*upcalls,
* already. */
if (may_put && upcall->type == DPIF_UC_MISS) {
struct ofpbuf mask;
- bool megaflow;
- atomic_read(&enable_megaflows, &megaflow);
ofpbuf_use_stack(&mask, &mask_bufs[i], sizeof mask_bufs[i]);
+
if (megaflow) {
size_t max_mpls;
bool recirc;
@@ -1503,7 +1507,7 @@ revalidate(struct revalidator *revalidator)
unsigned int flow_limit;
dump_seq = seq_read(udpif->dump_seq);
- atomic_read(&udpif->flow_limit, &flow_limit);
+ atomic_read_relaxed(&udpif->flow_limit, &flow_limit);
dump_thread = dpif_flow_dump_thread_create(udpif->dump);
for (;;) {
struct dump_op ops[REVALIDATE_MAX_BATCH];
@@ -1670,7 +1674,7 @@ upcall_unixctl_show(struct unixctl_conn *conn, int argc
OVS_UNUSED,
unsigned int flow_limit;
size_t i;
- atomic_read(&udpif->flow_limit, &flow_limit);
+ atomic_read_relaxed(&udpif->flow_limit, &flow_limit);
ds_put_format(&ds, "%s:\n", dpif_name(udpif->dpif));
ds_put_format(&ds, "\tflows : (current %lu)"
@@ -1703,7 +1707,7 @@ upcall_unixctl_disable_megaflows(struct unixctl_conn
*conn,
const char *argv[] OVS_UNUSED,
void *aux OVS_UNUSED)
{
- atomic_store(&enable_megaflows, false);
+ atomic_store_relaxed(&enable_megaflows, false);
udpif_flush_all_datapaths();
unixctl_command_reply(conn, "megaflows disabled");
}
@@ -1718,7 +1722,7 @@ upcall_unixctl_enable_megaflows(struct unixctl_conn *conn,
const char *argv[] OVS_UNUSED,
void *aux OVS_UNUSED)
{
- atomic_store(&enable_megaflows, true);
+ atomic_store_relaxed(&enable_megaflows, true);
udpif_flush_all_datapaths();
unixctl_command_reply(conn, "megaflows enabled");
}
@@ -1738,7 +1742,7 @@ upcall_unixctl_set_flow_limit(struct unixctl_conn *conn,
unsigned int flow_limit = atoi(argv[1]);
LIST_FOR_EACH (udpif, list_node, &all_udpifs) {
- atomic_store(&udpif->flow_limit, flow_limit);
+ atomic_store_relaxed(&udpif->flow_limit, flow_limit);
}
ds_put_format(&ds, "set flow_limit to %u\n", flow_limit);
unixctl_command_reply(conn, ds_cstr(&ds));
--
1.7.10.4
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