I have not tested yet
However, I would have expected something max latency config. to be specific to
netdev-dpdk port types
This type of code also seems to intersect with present and future QoS
considerations in netdev-dpdk
-----Original Message-----
From: Ilya Maximets <i.maxim...@samsung.com>
Date: Wednesday, July 26, 2017 at 8:21 AM
To: "ovs-dev@openvswitch.org" <ovs-dev@openvswitch.org>, Bhanuprakash Bodireddy
<bhanuprakash.bodire...@intel.com>
Cc: Heetae Ahn <heetae82....@samsung.com>, Ben Pfaff <b...@ovn.org>, Antonio
Fischetti <antonio.fische...@intel.com>, Eelco Chaudron <echau...@redhat.com>,
Ciara Loftus <ciara.lof...@intel.com>, Kevin Traynor <ktray...@redhat.com>,
Darrell Ball <db...@vmware.com>, Ilya Maximets <i.maxim...@samsung.com>
Subject: [PATCH RFC v2 4/4] dpif-netdev: Time based output batching.
This allows to collect packets from more than one RX burst
and send them together with a configurable maximum latency.
'other_config:output-max-latency' can be used to configure
time that a packet can wait in output batch for sending.
Signed-off-by: Ilya Maximets <i.maxim...@samsung.com>
---
millisecon granularity is used for now. Can be easily switched to use
microseconds instead.
lib/dpif-netdev.c | 97
+++++++++++++++++++++++++++++++++++++++++++---------
vswitchd/vswitch.xml | 15 ++++++++
2 files changed, 95 insertions(+), 17 deletions(-)
diff --git a/lib/dpif-netdev.c b/lib/dpif-netdev.c
index 07c7dad..e5f8a3d 100644
--- a/lib/dpif-netdev.c
+++ b/lib/dpif-netdev.c
@@ -84,6 +84,9 @@ VLOG_DEFINE_THIS_MODULE(dpif_netdev);
#define MAX_RECIRC_DEPTH 5
DEFINE_STATIC_PER_THREAD_DATA(uint32_t, recirc_depth, 0)
+/* Use instant packet send by default. */
+#define DEFAULT_OUTPUT_MAX_LATENCY 0
+
/* Configuration parameters. */
enum { MAX_FLOWS = 65536 }; /* Maximum number of flows in flow table.
*/
enum { MAX_METERS = 65536 }; /* Maximum number of meters. */
@@ -261,6 +264,9 @@ struct dp_netdev {
struct hmap ports;
struct seq *port_seq; /* Incremented whenever a port changes. */
+ /* The time that a packet can wait in output batch for sending. */
+ atomic_uint32_t output_max_latency;
+
/* Meters. */
struct ovs_mutex meter_locks[N_METER_LOCKS];
struct dp_meter *meters[MAX_METERS]; /* Meter bands. */
@@ -498,6 +504,7 @@ struct tx_port {
int qid;
long long last_used;
struct hmap_node node;
+ long long output_time;
struct dp_packet_batch output_pkts;
};
@@ -570,6 +577,9 @@ struct dp_netdev_pmd_thread {
* than 'cmap_count(dp->poll_threads)'. */
const int static_tx_qid;
+ /* Number of filled output batches. */
+ int n_output_batches;
+
struct ovs_mutex port_mutex; /* Mutex for 'poll_list' and
'tx_ports'. */
/* List of rx queues to poll. */
struct hmap poll_list OVS_GUARDED;
@@ -663,9 +673,9 @@ static void dp_netdev_add_rxq_to_pmd(struct
dp_netdev_pmd_thread *pmd,
static void dp_netdev_del_rxq_from_pmd(struct dp_netdev_pmd_thread *pmd,
struct rxq_poll *poll)
OVS_REQUIRES(pmd->port_mutex);
-static void
+static int
dp_netdev_pmd_flush_output_packets(struct dp_netdev_pmd_thread *pmd,
- long long now);
+ long long now, bool force);
static void reconfigure_datapath(struct dp_netdev *dp)
OVS_REQUIRES(dp->port_mutex);
static bool dp_netdev_pmd_try_ref(struct dp_netdev_pmd_thread *pmd);
@@ -1188,6 +1198,7 @@ create_dp_netdev(const char *name, const struct
dpif_class *class,
conntrack_init(&dp->conntrack);
atomic_init(&dp->emc_insert_min, DEFAULT_EM_FLOW_INSERT_MIN);
+ atomic_init(&dp->output_max_latency, DEFAULT_OUTPUT_MAX_LATENCY);
cmap_init(&dp->poll_threads);
ovs_mutex_init_recursive(&dp->non_pmd_mutex);
@@ -2843,7 +2854,7 @@ dpif_netdev_execute(struct dpif *dpif, struct
dpif_execute *execute)
dp_packet_batch_init_packet(&pp, execute->packet);
dp_netdev_execute_actions(pmd, &pp, false, execute->flow,
execute->actions, execute->actions_len, now);
- dp_netdev_pmd_flush_output_packets(pmd, now);
+ dp_netdev_pmd_flush_output_packets(pmd, now, true);
if (pmd->core_id == NON_PMD_CORE_ID) {
ovs_mutex_unlock(&dp->non_pmd_mutex);
@@ -2892,6 +2903,16 @@ dpif_netdev_set_config(struct dpif *dpif, const
struct smap *other_config)
smap_get_ullong(other_config, "emc-insert-inv-prob",
DEFAULT_EM_FLOW_INSERT_INV_PROB);
uint32_t insert_min, cur_min;
+ uint32_t output_max_latency, cur_max_latency;
+
+ output_max_latency = smap_get_int(other_config, "output-max-latency",
+ DEFAULT_OUTPUT_MAX_LATENCY);
+ atomic_read_relaxed(&dp->output_max_latency, &cur_max_latency);
+ if (output_max_latency != cur_max_latency) {
+ atomic_store_relaxed(&dp->output_max_latency, output_max_latency);
+ VLOG_INFO("Output maximum latency set to %"PRIu32" ms",
+ output_max_latency);
+ }
if (!nullable_string_is_equal(dp->pmd_cmask, cmask)) {
free(dp->pmd_cmask);
@@ -3092,11 +3113,12 @@ cycles_count_intermediate(struct
dp_netdev_pmd_thread *pmd,
non_atomic_ullong_add(&pmd->cycles.n[type], interval);
}
-static void
+static int
dp_netdev_pmd_flush_output_on_port(struct dp_netdev_pmd_thread *pmd,
struct tx_port *p, long long now)
{
int tx_qid;
+ int output_cnt;
bool dynamic_txqs;
dynamic_txqs = p->port->dynamic_txqs;
@@ -3106,21 +3128,39 @@ dp_netdev_pmd_flush_output_on_port(struct
dp_netdev_pmd_thread *pmd,
tx_qid = pmd->static_tx_qid;
}
+ output_cnt = dp_packet_batch_size(&p->output_pkts);
netdev_send(p->port->netdev, tx_qid, &p->output_pkts, dynamic_txqs);
dp_packet_batch_init(&p->output_pkts);
+
+ if (output_cnt) {
+ ovs_assert(pmd->n_output_batches > 0);
+ pmd->n_output_batches--;
+ }
+ return output_cnt;
}
-static void
+static int
dp_netdev_pmd_flush_output_packets(struct dp_netdev_pmd_thread *pmd,
- long long now)
+ long long now, bool force)
{
struct tx_port *p;
+ int output_cnt = 0;
+
+ if (!pmd->n_output_batches) {
+ return 0;
+ }
+
+ if (!now) {
+ now = time_msec();
+ }
HMAP_FOR_EACH (p, node, &pmd->send_port_cache) {
- if (!dp_packet_batch_is_empty(&p->output_pkts)) {
- dp_netdev_pmd_flush_output_on_port(pmd, p, now);
+ if (!dp_packet_batch_is_empty(&p->output_pkts)
+ && (force || p->output_time <= now)) {
+ output_cnt += dp_netdev_pmd_flush_output_on_port(pmd, p, now);
}
}
+ return output_cnt;
}
static int
@@ -3130,7 +3170,7 @@ dp_netdev_process_rxq_port(struct
dp_netdev_pmd_thread *pmd,
{
struct dp_packet_batch batch;
int error;
- int batch_cnt = 0;
+ int batch_cnt = 0, output_cnt = 0;
dp_packet_batch_init(&batch);
error = netdev_rxq_recv(rx, &batch);
@@ -3141,7 +3181,7 @@ dp_netdev_process_rxq_port(struct
dp_netdev_pmd_thread *pmd,
batch_cnt = batch.count;
dp_netdev_input(pmd, &batch, port_no, now);
- dp_netdev_pmd_flush_output_packets(pmd, now);
+ output_cnt = dp_netdev_pmd_flush_output_packets(pmd, now, false);
} else if (error != EAGAIN && error != EOPNOTSUPP) {
static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(1, 5);
@@ -3149,7 +3189,7 @@ dp_netdev_process_rxq_port(struct
dp_netdev_pmd_thread *pmd,
netdev_rxq_get_name(rx), ovs_strerror(error));
}
- return batch_cnt;
+ return batch_cnt + output_cnt;
}
static struct tx_port *
@@ -3685,6 +3725,8 @@ pmd_free_cached_ports(struct dp_netdev_pmd_thread
*pmd)
{
struct tx_port *tx_port_cached;
+ /* Flush all the queued packets. */
+ dp_netdev_pmd_flush_output_packets(pmd, 0, true);
/* Free all used tx queue ids. */
dpif_netdev_xps_revalidate_pmd(pmd, 0, true);
@@ -3759,7 +3801,6 @@ pmd_thread_main(void *f_)
bool exiting;
int poll_cnt;
int i;
- int process_packets = 0;
poll_list = NULL;
@@ -3788,8 +3829,10 @@ reload:
cycles_count_start(pmd);
for (;;) {
+ int process_packets = 0;
+
for (i = 0; i < poll_cnt; i++) {
- process_packets =
+ process_packets +=
dp_netdev_process_rxq_port(pmd, poll_list[i].rx,
poll_list[i].port_no);
cycles_count_intermediate(pmd,
@@ -3797,6 +3840,16 @@ reload:
: PMD_CYCLES_IDLE);
}
+ if (!process_packets) {
+ /* We didn't receive anything in the process loop.
+ * Check if we need to send something. */
+ process_packets = dp_netdev_pmd_flush_output_packets(pmd,
+ 0, false);
+ cycles_count_intermediate(pmd,
+ process_packets ?
PMD_CYCLES_PROCESSING
+ : PMD_CYCLES_IDLE);
+ }
+
if (lc++ > 1024) {
bool reload;
@@ -4234,6 +4287,8 @@ dp_netdev_configure_pmd(struct dp_netdev_pmd_thread
*pmd, struct dp_netdev *dp,
pmd->numa_id = numa_id;
pmd->need_reload = false;
+ pmd->n_output_batches = 0;
+
*CONST_CAST(int *, &pmd->static_tx_qid) =
cmap_count(&dp->poll_threads);
ovs_refcount_init(&pmd->ref_cnt);
@@ -4418,6 +4473,7 @@ dp_netdev_add_port_tx_to_pmd(struct
dp_netdev_pmd_thread *pmd,
tx->port = port;
tx->qid = -1;
+ tx->output_time = 0LL;
dp_packet_batch_init(&tx->output_pkts);
hmap_insert(&pmd->tx_ports, &tx->node,
hash_port_no(tx->port->port_no));
@@ -5094,11 +5150,18 @@ dp_execute_cb(void *aux_, struct dp_packet_batch
*packets_,
dp_netdev_pmd_flush_output_on_port(pmd, p, now);
}
#endif
+ if (dp_packet_batch_is_empty(&p->output_pkts)) {
+ uint32_t cur_max_latency;
+
+ atomic_read_relaxed(&dp->output_max_latency,
&cur_max_latency);
+ p->output_time = now + cur_max_latency;
- if (OVS_UNLIKELY(dp_packet_batch_size(&p->output_pkts)
- + dp_packet_batch_size(packets_) >
NETDEV_MAX_BURST)) {
- /* Some packets was generated while input batch processing.
- * Flush here to avoid overflow. */
+ if (dp_packet_batch_size(packets_)) {
+ pmd->n_output_batches++;
+ }
+ } else if (dp_packet_batch_size(&p->output_pkts)
+ + dp_packet_batch_size(packets_) >
NETDEV_MAX_BURST) {
+ /* Flush here to avoid overflow. */
dp_netdev_pmd_flush_output_on_port(pmd, p, now);
}
diff --git a/vswitchd/vswitch.xml b/vswitchd/vswitch.xml
index 074535b..23930f0 100644
--- a/vswitchd/vswitch.xml
+++ b/vswitchd/vswitch.xml
@@ -344,6 +344,21 @@
</p>
</column>
+ <column name="other_config" key="output-max-latency"
+ type='{"type": "integer", "minInteger": 0, "maxInteger":
1000}'>
+ <p>
+ Specifies the time in milliseconds that a packet can wait in
output
+ batch for sending i.e. amount of time that packet can spend in an
+ intermediate output queue before sending to netdev.
+ This option can be used to configure balance between throughput
+ and latency. Lower values decreases latency while higher values
+ may be useful to achieve higher performance.
+ </p>
+ <p>
+ Defaults to 0 i.e. instant packet sending (latency optimized).
+ </p>
+ </column>
+
<column name="other_config" key="n-handler-threads"
type='{"type": "integer", "minInteger": 1}'>
<p>
--
2.7.4
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