[ovs-dev] [PATCH v5] dpif-netdev: Add round-robin based rxq to pmd assignment.
Kevin Traynor
ktraynor at redhat.com
Fri Aug 31 09:08:35 UTC 2018
On 08/31/2018 09:56 AM, Eelco Chaudron wrote:
>
>
> On 31 Aug 2018, at 10:47, Kevin Traynor wrote:
>
>> Prior to OVS 2.9 automatic assignment of Rxqs to PMDs
>> (i.e. CPUs) was done by round-robin.
>>
>> That was changed in OVS 2.9 to ordering the Rxqs based on
>> their measured processing cycles. This was to assign the
>> busiest Rxqs to different PMDs, improving aggregate
>> throughput.
>>
>> For the most part the new scheme should be better, but
>> there could be situations where a user prefers a simple
>> round-robin scheme because Rxqs from a single port are
>> more likely to be spread across multiple PMDs, and/or
>> traffic is very bursty/unpredictable.
>>
>> Add 'pmd-rxq-assign' config to allow a user to select
>> round-robin based assignment.
>>
>> Signed-off-by: Kevin Traynor <ktraynor at redhat.com>
>> Acked-by: Eelco Chaudron <echaudro at redhat.com>
>
> You kept my ack, but anyway I looked at it again…
>
> Acked-by: Eelco Chaudron <echaudro at redhat.com>
>
thanks!
>> ---
>>
>> V5:
>> - Squashed NEWS into main patch (Ben)
>>
>> V4:
>> - Modified warning log (Ilya)
>>
>> V3:
>> - Rolled in some style and vswitch.xml changes (Ilya)
>> - Set cycles mode by default on wrong config (Ilya)
>>
>> V2:
>> - simplified nextpmd change (Eelco)
>> - removed confusing doc sentence (Eelco)
>> - fixed commit msg (Ilya)
>> - made change in pmd-rxq-assign value also perform re-assignment (Ilya)
>> - renamed to roundrobin mode (Ilya)
>> - moved vswitch.xml changes to right config section (Ilya)
>> - comment/log updates
>> - moved NEWS update to separate patch as it's been changing on master
>>
>> Documentation/topics/dpdk/pmd.rst | 33 +++++++++++++---
>> NEWS | 4 +-
>> lib/dpif-netdev.c | 83
>> +++++++++++++++++++++++++++++----------
>> tests/pmd.at | 12 +++++-
>> vswitchd/vswitch.xml | 24 +++++++++++
>> 5 files changed, 126 insertions(+), 30 deletions(-)
>>
>> diff --git a/Documentation/topics/dpdk/pmd.rst
>> b/Documentation/topics/dpdk/pmd.rst
>> index 5f0671e..dd9172d 100644
>> --- a/Documentation/topics/dpdk/pmd.rst
>> +++ b/Documentation/topics/dpdk/pmd.rst
>> @@ -113,10 +113,15 @@ means that this thread will only poll the
>> *pinned* Rx queues.
>>
>> If ``pmd-rxq-affinity`` is not set for Rx queues, they will be
>> assigned to PMDs
>> -(cores) automatically. Where known, the processing cycles that have
>> been stored
>> -for each Rx queue will be used to assign Rx queue to PMDs based on a
>> round
>> -robin of the sorted Rx queues. For example, take the following
>> example, where
>> -there are five Rx queues and three cores - 3, 7, and 8 - available
>> and the
>> -measured usage of core cycles per Rx queue over the last interval is
>> seen to
>> -be:
>> +(cores) automatically.
>> +
>> +The algorithm used to automatically assign Rxqs to PMDs can be set by::
>> +
>> + $ ovs-vsctl set Open_vSwitch .
>> other_config:pmd-rxq-assign=<assignment>
>> +
>> +By default, ``cycles`` assignment is used where the Rxqs will be
>> ordered by
>> +their measured processing cycles, and then be evenly assigned in
>> descending
>> +order to PMDs based on an up/down walk of the PMDs. For example,
>> where there
>> +are five Rx queues and three cores - 3, 7, and 8 - available and the
>> measured
>> +usage of core cycles per Rx queue over the last interval is seen to be:
>>
>> - Queue #0: 30%
>> @@ -132,4 +137,20 @@ The Rx queues will be assigned to the cores in
>> the following order::
>> Core 8: Q3 (60%) | Q0 (30%)
>>
>> +Alternatively, ``roundrobin`` assignment can be used, where the Rxqs are
>> +assigned to PMDs in a round-robined fashion. This algorithm was used by
>> +default prior to OVS 2.9. For example, given the following ports and
>> queues:
>> +
>> +- Port #0 Queue #0 (P0Q0)
>> +- Port #0 Queue #1 (P0Q1)
>> +- Port #1 Queue #0 (P1Q0)
>> +- Port #1 Queue #1 (P1Q1)
>> +- Port #1 Queue #2 (P1Q2)
>> +
>> +The Rx queues may be assigned to the cores in the following order::
>> +
>> + Core 3: P0Q0 | P1Q1
>> + Core 7: P0Q1 | P1Q2
>> + Core 8: P1Q0 |
>> +
>> To see the current measured usage history of PMD core cycles for each Rx
>> queue::
>> diff --git a/NEWS b/NEWS
>> index 33b4d8a..33b3638 100644
>> --- a/NEWS
>> +++ b/NEWS
>> @@ -9,5 +9,7 @@ Post-v2.10.0
>> - ovn:
>> * ovn-ctl: allow passing user:group ids to the OVN daemons.
>> -
>> + - DPDK:
>> + * Add option for simple round-robin based Rxq to PMD assignment.
>> + It can be set with pmd-rxq-assign.
>>
>> v2.10.0 - xx xxx xxxx
>> diff --git a/lib/dpif-netdev.c b/lib/dpif-netdev.c
>> index 807a462..ae24e6a 100644
>> --- a/lib/dpif-netdev.c
>> +++ b/lib/dpif-netdev.c
>> @@ -349,4 +349,6 @@ struct dp_netdev {
>> struct id_pool *tx_qid_pool;
>> struct ovs_mutex tx_qid_pool_mutex;
>> + /* Use measured cycles for rxq to pmd assignment. */
>> + bool pmd_rxq_assign_cyc;
>>
>> /* Protects the access of the 'struct dp_netdev_pmd_thread'
>> @@ -1500,4 +1502,5 @@ create_dp_netdev(const char *name, const struct
>> dpif_class *class,
>>
>> cmap_init(&dp->poll_threads);
>> + dp->pmd_rxq_assign_cyc = true;
>>
>> ovs_mutex_init(&dp->tx_qid_pool_mutex);
>> @@ -3724,4 +3727,6 @@ dpif_netdev_set_config(struct dpif *dpif, const
>> struct smap *other_config)
>> struct dp_netdev *dp = get_dp_netdev(dpif);
>> const char *cmask = smap_get(other_config, "pmd-cpu-mask");
>> + const char *pmd_rxq_assign = smap_get_def(other_config,
>> "pmd-rxq-assign",
>> + "cycles");
>> unsigned long long insert_prob =
>> smap_get_ullong(other_config, "emc-insert-inv-prob",
>> @@ -3786,4 +3791,18 @@ dpif_netdev_set_config(struct dpif *dpif, const
>> struct smap *other_config)
>> }
>> }
>> +
>> + bool pmd_rxq_assign_cyc = !strcmp(pmd_rxq_assign, "cycles");
>> + if (!pmd_rxq_assign_cyc && strcmp(pmd_rxq_assign, "roundrobin")) {
>> + VLOG_WARN("Unsupported Rxq to PMD assignment mode in
>> pmd-rxq-assign. "
>> + "Defaulting to 'cycles'.");
>> + pmd_rxq_assign_cyc = true;
>> + pmd_rxq_assign = "cycles";
>> + }
>> + if (dp->pmd_rxq_assign_cyc != pmd_rxq_assign_cyc) {
>> + dp->pmd_rxq_assign_cyc = pmd_rxq_assign_cyc;
>> + VLOG_INFO("Rxq to PMD assignment mode changed to: \'%s\'.",
>> + pmd_rxq_assign);
>> + dp_netdev_request_reconfigure(dp);
>> + }
>> return 0;
>> }
>> @@ -4256,8 +4275,16 @@ rr_numa_list_populate(struct dp_netdev *dp,
>> struct rr_numa_list *rr)
>> }
>>
>> -/* Returns the next pmd from the numa node in
>> - * incrementing or decrementing order. */
>> +/*
>> + * Returns the next pmd from the numa node.
>> + *
>> + * If 'updown' is 'true' it will alternate between selecting the next
>> pmd in
>> + * either an up or down walk, switching between up/down when the
>> first or last
>> + * core is reached. e.g. 1,2,3,3,2,1,1,2...
>> + *
>> + * If 'updown' is 'false' it will select the next pmd wrapping around
>> when last
>> + * core reached. e.g. 1,2,3,1,2,3,1,2...
>> + */
>> static struct dp_netdev_pmd_thread *
>> -rr_numa_get_pmd(struct rr_numa *numa)
>> +rr_numa_get_pmd(struct rr_numa *numa, bool updown)
>> {
>> int numa_idx = numa->cur_index;
>> @@ -4267,5 +4294,9 @@ rr_numa_get_pmd(struct rr_numa *numa)
>> if (numa->cur_index == numa->n_pmds-1) {
>> /* Reached the last pmd. */
>> - numa->idx_inc = false;
>> + if (updown) {
>> + numa->idx_inc = false;
>> + } else {
>> + numa->cur_index = 0;
>> + }
>> } else {
>> numa->cur_index++;
>> @@ -4330,7 +4361,4 @@ compare_rxq_cycles(const void *a, const void *b)
>> * pmds to unpinned queues.
>> *
>> - * If 'pinned' is false queues will be sorted by processing cycles
>> they are
>> - * consuming and then assigned to pmds in round robin order.
>> - *
>> * The function doesn't touch the pmd threads, it just stores the
>> assignment
>> * in the 'pmd' member of each rxq. */
>> @@ -4345,4 +4373,5 @@ rxq_scheduling(struct dp_netdev *dp, bool
>> pinned) OVS_REQUIRES(dp->port_mutex)
>> struct rr_numa *numa = NULL;
>> int numa_id;
>> + bool assign_cyc = dp->pmd_rxq_assign_cyc;
>>
>> HMAP_FOR_EACH (port, node, &dp->ports) {
>> @@ -4375,10 +4404,13 @@ rxq_scheduling(struct dp_netdev *dp, bool
>> pinned) OVS_REQUIRES(dp->port_mutex)
>> rxqs = xrealloc(rxqs, sizeof *rxqs * (n_rxqs + 1));
>> }
>> - /* Sum the queue intervals and store the cycle
>> history. */
>> - for (unsigned i = 0; i < PMD_RXQ_INTERVAL_MAX; i++) {
>> - cycle_hist += dp_netdev_rxq_get_intrvl_cycles(q, i);
>> - }
>> - dp_netdev_rxq_set_cycles(q, RXQ_CYCLES_PROC_HIST,
>> cycle_hist);
>>
>> + if (assign_cyc) {
>> + /* Sum the queue intervals and store the cycle
>> history. */
>> + for (unsigned i = 0; i < PMD_RXQ_INTERVAL_MAX;
>> i++) {
>> + cycle_hist +=
>> dp_netdev_rxq_get_intrvl_cycles(q, i);
>> + }
>> + dp_netdev_rxq_set_cycles(q, RXQ_CYCLES_PROC_HIST,
>> + cycle_hist);
>> + }
>> /* Store the queue. */
>> rxqs[n_rxqs++] = q;
>> @@ -4387,5 +4419,5 @@ rxq_scheduling(struct dp_netdev *dp, bool
>> pinned) OVS_REQUIRES(dp->port_mutex)
>> }
>>
>> - if (n_rxqs > 1) {
>> + if (n_rxqs > 1 && assign_cyc) {
>> /* Sort the queues in order of the processing cycles
>> * they consumed during their last pmd interval. */
>> @@ -4411,5 +4443,5 @@ rxq_scheduling(struct dp_netdev *dp, bool
>> pinned) OVS_REQUIRES(dp->port_mutex)
>> continue;
>> }
>> - rxqs[i]->pmd = rr_numa_get_pmd(non_local_numa);
>> + rxqs[i]->pmd = rr_numa_get_pmd(non_local_numa, assign_cyc);
>> VLOG_WARN("There's no available (non-isolated) pmd thread "
>> "on numa node %d. Queue %d on port \'%s\' will "
>> @@ -4420,11 +4452,20 @@ rxq_scheduling(struct dp_netdev *dp, bool
>> pinned) OVS_REQUIRES(dp->port_mutex)
>> rxqs[i]->pmd->core_id, rxqs[i]->pmd->numa_id);
>> } else {
>> - rxqs[i]->pmd = rr_numa_get_pmd(numa);
>> - VLOG_INFO("Core %d on numa node %d assigned port \'%s\' "
>> - "rx queue %d (measured processing cycles %"PRIu64").",
>> - rxqs[i]->pmd->core_id, numa_id,
>> - netdev_rxq_get_name(rxqs[i]->rx),
>> - netdev_rxq_get_queue_id(rxqs[i]->rx),
>> - dp_netdev_rxq_get_cycles(rxqs[i],
>> RXQ_CYCLES_PROC_HIST));
>> + rxqs[i]->pmd = rr_numa_get_pmd(numa, assign_cyc);
>> + if (assign_cyc) {
>> + VLOG_INFO("Core %d on numa node %d assigned port
>> \'%s\' "
>> + "rx queue %d "
>> + "(measured processing cycles %"PRIu64").",
>> + rxqs[i]->pmd->core_id, numa_id,
>> + netdev_rxq_get_name(rxqs[i]->rx),
>> + netdev_rxq_get_queue_id(rxqs[i]->rx),
>> + dp_netdev_rxq_get_cycles(rxqs[i],
>> +
>> RXQ_CYCLES_PROC_HIST));
>> + } else {
>> + VLOG_INFO("Core %d on numa node %d assigned port
>> \'%s\' "
>> + "rx queue %d.", rxqs[i]->pmd->core_id,
>> numa_id,
>> + netdev_rxq_get_name(rxqs[i]->rx),
>> + netdev_rxq_get_queue_id(rxqs[i]->rx));
>> + }
>> }
>> }
>> diff --git a/tests/pmd.at b/tests/pmd.at
>> index 4cae6c8..1f952f3 100644
>> --- a/tests/pmd.at
>> +++ b/tests/pmd.at
>> @@ -62,5 +62,6 @@ m4_define([CHECK_PMD_THREADS_CREATED], [
>>
>> m4_define([SED_NUMA_CORE_PATTERN], ["s/\(numa_id \)[[0-9]]*\( core_id
>> \)[[0-9]]*:/\1<cleared>\2<cleared>:/"])
>> -m4_define([SED_NUMA_CORE_QUEUE_PATTERN], ["s/1 2 5 6/<group>/;s/0 3 4
>> 7/<group>/"])
>> +m4_define([SED_NUMA_CORE_QUEUE_CYC_PATTERN], ["s/1 2 5 6/<group>/;s/0
>> 3 4 7/<group>/"])
>> +m4_define([SED_NUMA_CORE_QUEUE_PQ_PATTERN], ["s/1 3 5 7/<group>/;s/0
>> 2 4 6/<group>/"])
>> m4_define([DUMMY_NUMA], [--dummy-numa="0,0,0,0"])
>>
>> @@ -146,9 +147,16 @@ pmd thread numa_id <cleared> core_id <cleared>:
>> ])
>>
>> +AT_CHECK([ovs-vsctl set Open_vSwitch .
>> other_config:pmd-rxq-assign=cycles])
>> TMP=$(cat ovs-vswitchd.log | wc -l | tr -d [[:blank:]])
>> AT_CHECK([ovs-vsctl set Open_vSwitch . other_config:pmd-cpu-mask=0x3])
>> CHECK_PMD_THREADS_CREATED([2], [], [+$TMP])
>>
>> -AT_CHECK([ovs-appctl dpif-netdev/pmd-rxq-show | sed
>> ':a;/AVAIL$/{N;s/\n//;ba;}' | parse_pmd_rxq_show_group | sed
>> SED_NUMA_CORE_QUEUE_PATTERN], [0], [dnl
>> +AT_CHECK([ovs-appctl dpif-netdev/pmd-rxq-show | sed
>> ':a;/AVAIL$/{N;s/\n//;ba;}' | parse_pmd_rxq_show_group | sed
>> SED_NUMA_CORE_QUEUE_CYC_PATTERN], [0], [dnl
>> +port: p0 queue-id: <group>
>> +port: p0 queue-id: <group>
>> +])
>> +
>> +AT_CHECK([ovs-vsctl set Open_vSwitch .
>> other_config:pmd-rxq-assign=roundrobin])
>> +AT_CHECK([ovs-appctl dpif-netdev/pmd-rxq-show | sed
>> ':a;/AVAIL$/{N;s/\n//;ba;}' | parse_pmd_rxq_show_group | sed
>> SED_NUMA_CORE_QUEUE_PQ_PATTERN], [0], [dnl
>> port: p0 queue-id: <group>
>> port: p0 queue-id: <group>
>> diff --git a/vswitchd/vswitch.xml b/vswitchd/vswitch.xml
>> index e318151..91d132d 100644
>> --- a/vswitchd/vswitch.xml
>> +++ b/vswitchd/vswitch.xml
>> @@ -433,4 +433,28 @@
>> </column>
>>
>> + <column name="other_config" key="pmd-rxq-assign"
>> + type='{"type": "string",
>> + "enum": ["set", ["cycles", "roundrobin"]]}'>
>> + <p>
>> + Specifies how RX queues will be automatically assigned to
>> CPU cores.
>> + Options:
>> + <dl>
>> + <dt><code>cycles</code></dt>
>> + <dd>Rxqs will be sorted by order of measured processing
>> cycles
>> + before being assigned to CPU cores.</dd>
>> + <dt><code>roundrobin</code></dt>
>> + <dd>Rxqs will be round-robined across CPU cores.</dd>
>> + </dl>
>> + </p>
>> + <p>
>> + The default value is <code>cycles</code>.
>> + </p>
>> + <p>
>> + Changing this value will affect an automatic re-assignment
>> of Rxqs to
>> + CPUs. Note: Rxqs mapped to CPU cores with
>> + <code>pmd-rxq-affinity</code> are unaffected.
>> + </p>
>> + </column>
>> +
>> <column name="other_config" key="n-handler-threads"
>> type='{"type": "integer", "minInteger": 1}'>
>> --
>> 1.8.3.1
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