[ovs-dev] [PATCH v3 1/2] dpif-netdev: Add round-robin based rxq to pmd assignment.
Ilya Maximets
i.maximets at samsung.com
Mon Aug 27 15:04:24 UTC 2018
On 27.08.2018 17:19, Kevin Traynor wrote:
> On 08/27/2018 02:30 PM, Ilya Maximets wrote:
>> On 25.08.2018 13:00, 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>
>>> ---
>>>
>>> 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 +++++++++++++---
>>> lib/dpif-netdev.c | 83 +++++++++++++++++++++++++++++----------
>>> tests/pmd.at | 12 +++++-
>>> vswitchd/vswitch.xml | 24 +++++++++++
>>> 4 files changed, 123 insertions(+), 29 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/lib/dpif-netdev.c b/lib/dpif-netdev.c
>>> index 7f836bb..8f004c5 100644
>>> --- a/lib/dpif-netdev.c
>>> +++ b/lib/dpif-netdev.c
>>> @@ -342,4 +342,6 @@ 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'
>>> @@ -1493,4 +1495,5 @@ 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);
>>> @@ -3717,4 +3720,6 @@ 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",
>>> @@ -3779,4 +3784,18 @@ 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: "
>>> + "defaulting to 'cycles'.");
>>
>> Have you missed the actual printing of the wrong value?
>> Or that is what you wanted?
>>
>
> It was what I intended. If someone puts in junk, I didn't want to be
> adding it to the log.
>
Many functions in ovs prints wrong arguments. For example, LACP mode,
bond_mode, port type, getopt, VLAN mode, tc_set_policy and others.
IMHO, it's not bad to print what exactly the issue is, but I will
not insist.
One thing is that the colon makes me feel like you wanted to print
the exact string, but missed it. I think you should either replace
the colon with a period, or add a real value.
>>> + 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;
>>> }
>>> @@ -4249,8 +4268,16 @@ 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;
>>> @@ -4260,5 +4287,9 @@ 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++;
>>> @@ -4323,7 +4354,4 @@ 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. */
>>> @@ -4338,4 +4366,5 @@ 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) {
>>> @@ -4368,10 +4397,13 @@ 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;
>>> @@ -4380,5 +4412,5 @@ 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. */
>>> @@ -4404,5 +4436,5 @@ 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 "
>>> @@ -4413,11 +4445,20 @@ 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 0cd8520..2439b24 100644
>>> --- a/vswitchd/vswitch.xml
>>> +++ b/vswitchd/vswitch.xml
>>> @@ -425,4 +425,28 @@
>>> </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}'>
>>>
>
>
>
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