[ovs-dev] [OVN Patch v15 1/3] ovn-libs: Add support for parallel processing
Anton Ivanov
anton.ivanov at cambridgegreys.com
Mon Mar 29 15:48:06 UTC 2021
I have the it cleaned up and it is stable on the machine where I could reproduce your issue.
It was all in the exit sequence. That is why the testsuite was green - crashes were after all processing was complete.
I will clean it up, run it overnight for a final test and if it's all OK send a new version tomorrow.
A.
On 26/03/2021 08:07, Anton Ivanov wrote:
> On 26/03/2021 03:25, Numan Siddique wrote:
>> On Thu, Mar 25, 2021 at 3:01 PM Anton Ivanov
>> <anton.ivanov at cambridgegreys.com> wrote:
>>>
>>>
>>> On 24/03/2021 15:31, Numan Siddique wrote:
>>>> On Mon, Mar 1, 2021 at 6:35 PM <anton.ivanov at cambridgegreys.com> wrote:
>>>>> From: Anton Ivanov <anton.ivanov at cambridgegreys.com>
>>>>>
>>>>> This adds a set of functions and macros intended to process
>>>>> hashes in parallel.
>>>>>
>>>>> The principles of operation are documented in the ovn-parallel-hmap.h
>>>>>
>>>>> If these one day go into the OVS tree, the OVS tree versions
>>>>> would be used in preference.
>>>>>
>>>>> Signed-off-by: Anton Ivanov <anton.ivanov at cambridgegreys.com>
>>>> Hi Anton,
>>>>
>>>> I tested the first 2 patches of this series and it crashes again for me.
>>>>
>>>> This time I ran tests on a 4 core machine - Intel(R) Xeon(R) CPU
>>>> E3-1220 v5 @ 3.00GHz
>>>>
>>>> The below trace is seen for both gcc and clang.
>>>>
>>>> ----
>>>> [Thread debugging using libthread_db enabled]
>>>> Using host libthread_db library "/lib64/libthread_db.so.1".
>>>> Core was generated by `ovn-northd -vjsonrpc
>>>> --ovnnb-db=unix:/mnt/mydisk/myhome/numan_alt/work/ovs_ovn/'.
>>>> Program terminated with signal SIGSEGV, Segmentation fault.
>>>> #0 0x00007f27594ae212 in __new_sem_wait_slow.constprop.0 () from
>>>> /lib64/libpthread.so.0
>>>> [Current thread is 1 (Thread 0x7f2758c68640 (LWP 347378))]
>>>> Missing separate debuginfos, use: dnf debuginfo-install
>>>> glibc-2.32-3.fc33.x86_64 libcap-ng-0.8-1.fc33.x86_64
>>>> libevent-2.1.8-10.fc33.x86_64 openssl-libs-1.1.1i-1.fc33.x86_64
>>>> python3-libs-3.9.1-2.fc33.x86_64 unbound-libs-1.10.1-4.fc33.x86_64
>>>> zlib-1.2.11-23.fc33.x86_64
>>>> (gdb) bt
>>>> #0 0x00007f27594ae212 in __new_sem_wait_slow.constprop.0 () from
>>>> /lib64/libpthread.so.0
>>>> #1 0x0000000000422184 in wait_for_work (control=<optimized out>) at
>>>> ../lib/ovn-parallel-hmap.h:203
>>>> #2 build_lflows_thread (arg=0x2538420) at ../northd/ovn-northd.c:11855
>>>> #3 0x000000000049cd12 in ovsthread_wrapper (aux_=<optimized out>) at
>>>> ../lib/ovs-thread.c:383
>>>> #4 0x00007f27594a53f9 in start_thread () from /lib64/libpthread.so.0
>>>> #5 0x00007f2759142903 in clone () from /lib64/libc.so.6
>>>> -----
>>>>
>>>> I'm not sure why you're not able to reproduce this issue.
>>> I can't. I have run it for days in a loop.
>>>
>>> One possibility is that for whatever reason your machine has slower IPC speeds compared to linear execution speeds. Thread debugging? AMD vs Intel? No idea.
>>>
>>> There is a race on-exit in the current code which I have found by inspection and which I have never been able to trigger. On my machines the workers always exit in time before the main thread has finished, so I cannot trigger this.
>>>
>>> Can you try this incremental fix to see if it fixes the problem for you. If that works, I will incorporate it and reissue the patch. If not - I will continue digging.
>>>
>>> diff --git a/lib/ovn-parallel-hmap.c b/lib/ovn-parallel-hmap.c
>>> index e83ae23cb..3597f896f 100644
>>> --- a/lib/ovn-parallel-hmap.c
>>> +++ b/lib/ovn-parallel-hmap.c
>>> @@ -143,7 +143,8 @@ struct worker_pool *ovn_add_worker_pool(void *(*start)(void *)){
>>> }
>>>
>>> for (i = 0; i < pool_size; i++) {
>>> - ovs_thread_create("worker pool helper", start, &new_pool->controls[i]);
>>> + new_pool->controls[i].worker =
>>> + ovs_thread_create("worker pool helper", start, &new_pool->controls[i]);
>>> }
>>> ovs_list_push_back(&worker_pools, &new_pool->list_node);
>>> }
>>> @@ -386,6 +387,9 @@ static void worker_pool_hook(void *aux OVS_UNUSED) {
>>> for (i = 0; i < pool->size ; i++) {
>>> sem_post(pool->controls[i].fire);
>>> }
>>> + for (i = 0; i < pool->size ; i++) {
>>> + pthread_join(pool->controls[i].worker, NULL);
>>> + }
>>> for (i = 0; i < pool->size ; i++) {
>>> sem_close(pool->controls[i].fire);
>>> sprintf(sem_name, WORKER_SEM_NAME, sembase, pool, i);
>>> diff --git a/lib/ovn-parallel-hmap.h b/lib/ovn-parallel-hmap.h
>>> index 8db61eaba..d62ca3da5 100644
>>> --- a/lib/ovn-parallel-hmap.h
>>> +++ b/lib/ovn-parallel-hmap.h
>>> @@ -82,6 +82,7 @@ struct worker_control {
>>> struct ovs_mutex mutex; /* Guards the data. */
>>> void *data; /* Pointer to data to be processed. */
>>> void *workload; /* back-pointer to the worker pool structure. */
>>> + pthread_t worker;
>>> };
>>>
>>> struct worker_pool {
>>>
>> I applied the above diff on top of patch 2 and did some tests. I see
>> a big improvement
>> with this. On my "Intel(R) Xeon(R) CPU E3-1220 v5 @ 3.00GHz" server,
>> I saw just one
>> crash only once when I ran the test suite multiple times.
>>
>> On my work laptop (in which the tests used to hang earlier), all the
>> tests are passing now.
>> But I see a lot more consistent crashes here. For all single run of
>> whole testsuite (with make check -j5)
>> I observed around 7 crashes. Definitely an improvement when compared
>> to my previous runs with v14.
>>
>> Here are the back traces details of the core dumps I observed -
>> https://gist.github.com/numansiddique/5cab90ec4a1ee6e1adbfd3cd90eccf5a
>>
>> Crash 1 and Crash 2 are frequent. Let me know in case you want the core files.
>
> Not really. Traces are informative.
>
> I have no idea why I cannot reproduce these, but I can see where (roughly) is the problem.
>
> I can't see why (yet). The place where it crashes in 1 and 2 is the brute-force hash merge code which is trivial, runs on every iteration and has been tested quite thoroughly.
>
> I will look at it later today.
>
> Brgds,
>
>>
>> Thanks
>> Numan
>>
>>>> All the test cases passed for me. So maybe something's wrong when
>>>> ovn-northd exits.
>>>> IMHO, these crashes should be addressed before these patches can be considered.
>>>>
>>>> Thanks
>>>> Numan
>>>>
>>>>> ---
>>>>> lib/automake.mk | 2 +
>>>>> lib/ovn-parallel-hmap.c | 455 ++++++++++++++++++++++++++++++++++++++++
>>>>> lib/ovn-parallel-hmap.h | 301 ++++++++++++++++++++++++++
>>>>> 3 files changed, 758 insertions(+)
>>>>> create mode 100644 lib/ovn-parallel-hmap.c
>>>>> create mode 100644 lib/ovn-parallel-hmap.h
>>>>>
>>>>> diff --git a/lib/automake.mk b/lib/automake.mk
>>>>> index 250c7aefa..781be2109 100644
>>>>> --- a/lib/automake.mk
>>>>> +++ b/lib/automake.mk
>>>>> @@ -13,6 +13,8 @@ lib_libovn_la_SOURCES = \
>>>>> lib/expr.c \
>>>>> lib/extend-table.h \
>>>>> lib/extend-table.c \
>>>>> + lib/ovn-parallel-hmap.h \
>>>>> + lib/ovn-parallel-hmap.c \
>>>>> lib/ip-mcast-index.c \
>>>>> lib/ip-mcast-index.h \
>>>>> lib/mcast-group-index.c \
>>>>> diff --git a/lib/ovn-parallel-hmap.c b/lib/ovn-parallel-hmap.c
>>>>> new file mode 100644
>>>>> index 000000000..e83ae23cb
>>>>> --- /dev/null
>>>>> +++ b/lib/ovn-parallel-hmap.c
>>>>> @@ -0,0 +1,455 @@
>>>>> +/*
>>>>> + * Copyright (c) 2020 Red Hat, Inc.
>>>>> + * Copyright (c) 2008, 2009, 2010, 2012, 2013, 2015, 2019 Nicira, Inc.
>>>>> + *
>>>>> + * Licensed under the Apache License, Version 2.0 (the "License");
>>>>> + * you may not use this file except in compliance with the License.
>>>>> + * You may obtain a copy of the License at:
>>>>> + *
>>>>> + * http://www.apache.org/licenses/LICENSE-2.0
>>>>> + *
>>>>> + * Unless required by applicable law or agreed to in writing, software
>>>>> + * distributed under the License is distributed on an "AS IS" BASIS,
>>>>> + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
>>>>> + * See the License for the specific language governing permissions and
>>>>> + * limitations under the License.
>>>>> + */
>>>>> +
>>>>> +#include <config.h>
>>>>> +#include <stdint.h>
>>>>> +#include <string.h>
>>>>> +#include <stdlib.h>
>>>>> +#include <fcntl.h>
>>>>> +#include <unistd.h>
>>>>> +#include <errno.h>
>>>>> +#include <semaphore.h>
>>>>> +#include "fatal-signal.h"
>>>>> +#include "util.h"
>>>>> +#include "openvswitch/vlog.h"
>>>>> +#include "openvswitch/hmap.h"
>>>>> +#include "openvswitch/thread.h"
>>>>> +#include "ovn-parallel-hmap.h"
>>>>> +#include "ovs-atomic.h"
>>>>> +#include "ovs-thread.h"
>>>>> +#include "ovs-numa.h"
>>>>> +#include "random.h"
>>>>> +
>>>>> +VLOG_DEFINE_THIS_MODULE(ovn_parallel_hmap);
>>>>> +
>>>>> +#ifndef OVS_HAS_PARALLEL_HMAP
>>>>> +
>>>>> +#define WORKER_SEM_NAME "%x-%p-%x"
>>>>> +#define MAIN_SEM_NAME "%x-%p-main"
>>>>> +
>>>>> +/* These are accessed under mutex inside add_worker_pool().
>>>>> + * They do not need to be atomic.
>>>>> + */
>>>>> +
>>>>> +static atomic_bool initial_pool_setup = ATOMIC_VAR_INIT(false);
>>>>> +static bool can_parallelize = false;
>>>>> +
>>>>> +/* This is set only in the process of exit and the set is
>>>>> + * accompanied by a fence. It does not need to be atomic or be
>>>>> + * accessed under a lock.
>>>>> + */
>>>>> +
>>>>> +static bool workers_must_exit = false;
>>>>> +
>>>>> +static struct ovs_list worker_pools = OVS_LIST_INITIALIZER(&worker_pools);
>>>>> +
>>>>> +static struct ovs_mutex init_mutex = OVS_MUTEX_INITIALIZER;
>>>>> +
>>>>> +static int pool_size;
>>>>> +
>>>>> +static int sembase;
>>>>> +
>>>>> +static void worker_pool_hook(void *aux OVS_UNUSED);
>>>>> +static void setup_worker_pools(bool force);
>>>>> +static void merge_list_results(struct worker_pool *pool OVS_UNUSED,
>>>>> + void *fin_result, void *result_frags,
>>>>> + int index);
>>>>> +static void merge_hash_results(struct worker_pool *pool OVS_UNUSED,
>>>>> + void *fin_result, void *result_frags,
>>>>> + int index);
>>>>> +
>>>>> +bool ovn_stop_parallel_processing(void)
>>>>> +{
>>>>> + return workers_must_exit;
>>>>> +}
>>>>> +
>>>>> +bool ovn_can_parallelize_hashes(bool force_parallel)
>>>>> +{
>>>>> + bool test = false;
>>>>> +
>>>>> + if (atomic_compare_exchange_strong(
>>>>> + &initial_pool_setup,
>>>>> + &test,
>>>>> + true)) {
>>>>> + ovs_mutex_lock(&init_mutex);
>>>>> + setup_worker_pools(force_parallel);
>>>>> + ovs_mutex_unlock(&init_mutex);
>>>>> + }
>>>>> + return can_parallelize;
>>>>> +}
>>>>> +
>>>>> +struct worker_pool *ovn_add_worker_pool(void *(*start)(void *)){
>>>>> +
>>>>> + struct worker_pool *new_pool = NULL;
>>>>> + struct worker_control *new_control;
>>>>> + bool test = false;
>>>>> + int i;
>>>>> + char sem_name[256];
>>>>> +
>>>>> +
>>>>> + /* Belt and braces - initialize the pool system just in case if
>>>>> + * if it is not yet initialized.
>>>>> + */
>>>>> +
>>>>> + if (atomic_compare_exchange_strong(
>>>>> + &initial_pool_setup,
>>>>> + &test,
>>>>> + true)) {
>>>>> + ovs_mutex_lock(&init_mutex);
>>>>> + setup_worker_pools(false);
>>>>> + ovs_mutex_unlock(&init_mutex);
>>>>> + }
>>>>> +
>>>>> + ovs_mutex_lock(&init_mutex);
>>>>> + if (can_parallelize) {
>>>>> + new_pool = xmalloc(sizeof(struct worker_pool));
>>>>> + new_pool->size = pool_size;
>>>>> + new_pool->controls = NULL;
>>>>> + sprintf(sem_name, MAIN_SEM_NAME, sembase, new_pool);
>>>>> + new_pool->done = sem_open(sem_name, O_CREAT, S_IRWXU, 0);
>>>>> + if (new_pool->done == SEM_FAILED) {
>>>>> + goto cleanup;
>>>>> + }
>>>>> +
>>>>> + new_pool->controls =
>>>>> + xmalloc(sizeof(struct worker_control) * new_pool->size);
>>>>> +
>>>>> + for (i = 0; i < new_pool->size; i++) {
>>>>> + new_control = &new_pool->controls[i];
>>>>> + new_control->id = i;
>>>>> + new_control->done = new_pool->done;
>>>>> + new_control->data = NULL;
>>>>> + ovs_mutex_init(&new_control->mutex);
>>>>> + new_control->finished = ATOMIC_VAR_INIT(false);
>>>>> + sprintf(sem_name, WORKER_SEM_NAME, sembase, new_pool, i);
>>>>> + new_control->fire = sem_open(sem_name, O_CREAT, S_IRWXU, 0);
>>>>> + if (new_control->fire == SEM_FAILED) {
>>>>> + goto cleanup;
>>>>> + }
>>>>> + }
>>>>> +
>>>>> + for (i = 0; i < pool_size; i++) {
>>>>> + ovs_thread_create("worker pool helper", start, &new_pool->controls[i]);
>>>>> + }
>>>>> + ovs_list_push_back(&worker_pools, &new_pool->list_node);
>>>>> + }
>>>>> + ovs_mutex_unlock(&init_mutex);
>>>>> + return new_pool;
>>>>> +cleanup:
>>>>> +
>>>>> + /* Something went wrong when opening semaphores. In this case
>>>>> + * it is better to shut off parallel procesing altogether
>>>>> + */
>>>>> +
>>>>> + VLOG_INFO("Failed to initialize parallel processing, error %d", errno);
>>>>> + can_parallelize = false;
>>>>> + if (new_pool->controls) {
>>>>> + for (i = 0; i < new_pool->size; i++) {
>>>>> + if (new_pool->controls[i].fire != SEM_FAILED) {
>>>>> + sem_close(new_pool->controls[i].fire);
>>>>> + sprintf(sem_name, WORKER_SEM_NAME, sembase, new_pool, i);
>>>>> + sem_unlink(sem_name);
>>>>> + break; /* semaphores past this one are uninitialized */
>>>>> + }
>>>>> + }
>>>>> + }
>>>>> + if (new_pool->done != SEM_FAILED) {
>>>>> + sem_close(new_pool->done);
>>>>> + sprintf(sem_name, MAIN_SEM_NAME, sembase, new_pool);
>>>>> + sem_unlink(sem_name);
>>>>> + }
>>>>> + ovs_mutex_unlock(&init_mutex);
>>>>> + return NULL;
>>>>> +}
>>>>> +
>>>>> +
>>>>> +/* Initializes 'hmap' as an empty hash table with mask N. */
>>>>> +void
>>>>> +ovn_fast_hmap_init(struct hmap *hmap, ssize_t mask)
>>>>> +{
>>>>> + size_t i;
>>>>> +
>>>>> + hmap->buckets = xmalloc(sizeof (struct hmap_node *) * (mask + 1));
>>>>> + hmap->one = NULL;
>>>>> + hmap->mask = mask;
>>>>> + hmap->n = 0;
>>>>> + for (i = 0; i <= hmap->mask; i++) {
>>>>> + hmap->buckets[i] = NULL;
>>>>> + }
>>>>> +}
>>>>> +
>>>>> +/* Initializes 'hmap' as an empty hash table of size X.
>>>>> + * Intended for use in parallel processing so that all
>>>>> + * fragments used to store results in a parallel job
>>>>> + * are the same size.
>>>>> + */
>>>>> +void
>>>>> +ovn_fast_hmap_size_for(struct hmap *hmap, int size)
>>>>> +{
>>>>> + size_t mask;
>>>>> + mask = size / 2;
>>>>> + mask |= mask >> 1;
>>>>> + mask |= mask >> 2;
>>>>> + mask |= mask >> 4;
>>>>> + mask |= mask >> 8;
>>>>> + mask |= mask >> 16;
>>>>> +#if SIZE_MAX > UINT32_MAX
>>>>> + mask |= mask >> 32;
>>>>> +#endif
>>>>> +
>>>>> + /* If we need to dynamically allocate buckets we might as well allocate at
>>>>> + * least 4 of them. */
>>>>> + mask |= (mask & 1) << 1;
>>>>> +
>>>>> + fast_hmap_init(hmap, mask);
>>>>> +}
>>>>> +
>>>>> +/* Run a thread pool which uses a callback function to process results
>>>>> + */
>>>>> +
>>>>> +void ovn_run_pool_callback(struct worker_pool *pool,
>>>>> + void *fin_result, void *result_frags,
>>>>> + void (*helper_func)(struct worker_pool *pool,
>>>>> + void *fin_result,
>>>>> + void *result_frags, int index))
>>>>> +{
>>>>> + int index, completed;
>>>>> +
>>>>> + /* Ensure that all worker threads see the same data as the
>>>>> + * main thread.
>>>>> + */
>>>>> +
>>>>> + atomic_thread_fence(memory_order_acq_rel);
>>>>> +
>>>>> + /* Start workers */
>>>>> +
>>>>> + for (index = 0; index < pool->size; index++) {
>>>>> + sem_post(pool->controls[index].fire);
>>>>> + }
>>>>> +
>>>>> + completed = 0;
>>>>> +
>>>>> + do {
>>>>> + bool test;
>>>>> + /* Note - we do not loop on semaphore until it reaches
>>>>> + * zero, but on pool size/remaining workers.
>>>>> + * This is by design. If the inner loop can handle
>>>>> + * completion for more than one worker within an iteration
>>>>> + * it will do so to ensure no additional iterations and
>>>>> + * waits once all of them are done.
>>>>> + *
>>>>> + * This may result in us having an initial positive value
>>>>> + * of the semaphore when the pool is invoked the next time.
>>>>> + * This is harmless - the loop will spin up a couple of times
>>>>> + * doing nothing while the workers are processing their data
>>>>> + * slices.
>>>>> + */
>>>>> + wait_for_work_completion(pool);
>>>>> + for (index = 0; index < pool->size; index++) {
>>>>> + test = true;
>>>>> + /* If the worker has marked its data chunk as complete,
>>>>> + * invoke the helper function to combine the results of
>>>>> + * this worker into the main result.
>>>>> + *
>>>>> + * The worker must invoke an appropriate memory fence
>>>>> + * (most likely acq_rel) to ensure that the main thread
>>>>> + * sees all of the results produced by the worker.
>>>>> + */
>>>>> + if (atomic_compare_exchange_weak(
>>>>> + &pool->controls[index].finished,
>>>>> + &test,
>>>>> + false)) {
>>>>> + if (helper_func) {
>>>>> + (helper_func)(pool, fin_result, result_frags, index);
>>>>> + }
>>>>> + completed++;
>>>>> + pool->controls[index].data = NULL;
>>>>> + }
>>>>> + }
>>>>> + } while (completed < pool->size);
>>>>> +}
>>>>> +
>>>>> +/* Run a thread pool - basic, does not do results processing.
>>>>> + */
>>>>> +
>>>>> +void ovn_run_pool(struct worker_pool *pool)
>>>>> +{
>>>>> + run_pool_callback(pool, NULL, NULL, NULL);
>>>>> +}
>>>>> +
>>>>> +/* Brute force merge of a hashmap into another hashmap.
>>>>> + * Intended for use in parallel processing. The destination
>>>>> + * hashmap MUST be the same size as the one being merged.
>>>>> + *
>>>>> + * This can be achieved by pre-allocating them to correct size
>>>>> + * and using hmap_insert_fast() instead of hmap_insert()
>>>>> + */
>>>>> +
>>>>> +void ovn_fast_hmap_merge(struct hmap *dest, struct hmap *inc)
>>>>> +{
>>>>> + size_t i;
>>>>> +
>>>>> + ovs_assert(inc->mask == dest->mask);
>>>>> +
>>>>> + if (!inc->n) {
>>>>> + /* Request to merge an empty frag, nothing to do */
>>>>> + return;
>>>>> + }
>>>>> +
>>>>> + for (i = 0; i <= dest->mask; i++) {
>>>>> + struct hmap_node **dest_bucket = &dest->buckets[i];
>>>>> + struct hmap_node **inc_bucket = &inc->buckets[i];
>>>>> + if (*inc_bucket != NULL) {
>>>>> + struct hmap_node *last_node = *inc_bucket;
>>>>> + while (last_node->next != NULL) {
>>>>> + last_node = last_node->next;
>>>>> + }
>>>>> + last_node->next = *dest_bucket;
>>>>> + *dest_bucket = *inc_bucket;
>>>>> + *inc_bucket = NULL;
>>>>> + }
>>>>> + }
>>>>> + dest->n += inc->n;
>>>>> + inc->n = 0;
>>>>> +}
>>>>> +
>>>>> +/* Run a thread pool which gathers results in an array
>>>>> + * of hashes. Merge results.
>>>>> + */
>>>>> +
>>>>> +
>>>>> +void ovn_run_pool_hash(
>>>>> + struct worker_pool *pool,
>>>>> + struct hmap *result,
>>>>> + struct hmap *result_frags)
>>>>> +{
>>>>> + run_pool_callback(pool, result, result_frags, merge_hash_results);
>>>>> +}
>>>>> +
>>>>> +/* Run a thread pool which gathers results in an array of lists.
>>>>> + * Merge results.
>>>>> + */
>>>>> +void ovn_run_pool_list(
>>>>> + struct worker_pool *pool,
>>>>> + struct ovs_list *result,
>>>>> + struct ovs_list *result_frags)
>>>>> +{
>>>>> + run_pool_callback(pool, result, result_frags, merge_list_results);
>>>>> +}
>>>>> +
>>>>> +void ovn_update_hashrow_locks(struct hmap *lflows, struct hashrow_locks *hrl)
>>>>> +{
>>>>> + int i;
>>>>> + if (hrl->mask != lflows->mask) {
>>>>> + if (hrl->row_locks) {
>>>>> + free(hrl->row_locks);
>>>>> + }
>>>>> + hrl->row_locks = xcalloc(sizeof(struct ovs_mutex), lflows->mask + 1);
>>>>> + hrl->mask = lflows->mask;
>>>>> + for (i = 0; i <= lflows->mask; i++) {
>>>>> + ovs_mutex_init(&hrl->row_locks[i]);
>>>>> + }
>>>>> + }
>>>>> +}
>>>>> +
>>>>> +static void worker_pool_hook(void *aux OVS_UNUSED) {
>>>>> + int i;
>>>>> + static struct worker_pool *pool;
>>>>> + char sem_name[256];
>>>>> +
>>>>> + workers_must_exit = true;
>>>>> +
>>>>> + /* All workers must honour the must_exit flag and check for it regularly.
>>>>> + * We can make it atomic and check it via atomics in workers, but that
>>>>> + * is not really necessary as it is set just once - when the program
>>>>> + * terminates. So we use a fence which is invoked before exiting instead.
>>>>> + */
>>>>> + atomic_thread_fence(memory_order_acq_rel);
>>>>> +
>>>>> + /* Wake up the workers after the must_exit flag has been set */
>>>>> +
>>>>> + LIST_FOR_EACH (pool, list_node, &worker_pools) {
>>>>> + for (i = 0; i < pool->size ; i++) {
>>>>> + sem_post(pool->controls[i].fire);
>>>>> + }
>>>>> + for (i = 0; i < pool->size ; i++) {
>>>>> + sem_close(pool->controls[i].fire);
>>>>> + sprintf(sem_name, WORKER_SEM_NAME, sembase, pool, i);
>>>>> + sem_unlink(sem_name);
>>>>> + }
>>>>> + sem_close(pool->done);
>>>>> + sprintf(sem_name, MAIN_SEM_NAME, sembase, pool);
>>>>> + sem_unlink(sem_name);
>>>>> + }
>>>>> +}
>>>>> +
>>>>> +static void setup_worker_pools(bool force) {
>>>>> + int cores, nodes;
>>>>> +
>>>>> + nodes = ovs_numa_get_n_numas();
>>>>> + if (nodes == OVS_NUMA_UNSPEC || nodes <= 0) {
>>>>> + nodes = 1;
>>>>> + }
>>>>> + cores = ovs_numa_get_n_cores();
>>>>> +
>>>>> + /* If there is no NUMA config, use 4 cores.
>>>>> + * If there is NUMA config use half the cores on
>>>>> + * one node so that the OS does not start pushing
>>>>> + * threads to other nodes.
>>>>> + */
>>>>> + if (cores == OVS_CORE_UNSPEC || cores <= 0) {
>>>>> + /* If there is no NUMA we can try the ovs-threads routine.
>>>>> + * It falls back to sysconf and/or affinity mask.
>>>>> + */
>>>>> + cores = count_cpu_cores();
>>>>> + pool_size = cores;
>>>>> + } else {
>>>>> + pool_size = cores / nodes;
>>>>> + }
>>>>> + if ((pool_size < 4) && force) {
>>>>> + pool_size = 4;
>>>>> + }
>>>>> + can_parallelize = (pool_size >= 3);
>>>>> + fatal_signal_add_hook(worker_pool_hook, NULL, NULL, true);
>>>>> + sembase = random_uint32();
>>>>> +}
>>>>> +
>>>>> +static void merge_list_results(struct worker_pool *pool OVS_UNUSED,
>>>>> + void *fin_result, void *result_frags,
>>>>> + int index)
>>>>> +{
>>>>> + struct ovs_list *result = (struct ovs_list *)fin_result;
>>>>> + struct ovs_list *res_frags = (struct ovs_list *)result_frags;
>>>>> +
>>>>> + if (!ovs_list_is_empty(&res_frags[index])) {
>>>>> + ovs_list_splice(result->next,
>>>>> + ovs_list_front(&res_frags[index]), &res_frags[index]);
>>>>> + }
>>>>> +}
>>>>> +
>>>>> +static void merge_hash_results(struct worker_pool *pool OVS_UNUSED,
>>>>> + void *fin_result, void *result_frags,
>>>>> + int index)
>>>>> +{
>>>>> + struct hmap *result = (struct hmap *)fin_result;
>>>>> + struct hmap *res_frags = (struct hmap *)result_frags;
>>>>> +
>>>>> + fast_hmap_merge(result, &res_frags[index]);
>>>>> + hmap_destroy(&res_frags[index]);
>>>>> +}
>>>>> +
>>>>> +#endif
>>>>> diff --git a/lib/ovn-parallel-hmap.h b/lib/ovn-parallel-hmap.h
>>>>> new file mode 100644
>>>>> index 000000000..8db61eaba
>>>>> --- /dev/null
>>>>> +++ b/lib/ovn-parallel-hmap.h
>>>>> @@ -0,0 +1,301 @@
>>>>> +/*
>>>>> + * Copyright (c) 2020 Red Hat, Inc.
>>>>> + *
>>>>> + * Licensed under the Apache License, Version 2.0 (the "License");
>>>>> + * you may not use this file except in compliance with the License.
>>>>> + * You may obtain a copy of the License at:
>>>>> + *
>>>>> + * http://www.apache.org/licenses/LICENSE-2.0
>>>>> + *
>>>>> + * Unless required by applicable law or agreed to in writing, software
>>>>> + * distributed under the License is distributed on an "AS IS" BASIS,
>>>>> + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
>>>>> + * See the License for the specific language governing permissions and
>>>>> + * limitations under the License.
>>>>> + */
>>>>> +
>>>>> +#ifndef OVN_PARALLEL_HMAP
>>>>> +#define OVN_PARALLEL_HMAP 1
>>>>> +
>>>>> +/* if the parallel macros are defined by hmap.h or any other ovs define
>>>>> + * we skip over the ovn specific definitions.
>>>>> + */
>>>>> +
>>>>> +#ifdef __cplusplus
>>>>> +extern "C" {
>>>>> +#endif
>>>>> +
>>>>> +#include <stdbool.h>
>>>>> +#include <stdlib.h>
>>>>> +#include <semaphore.h>
>>>>> +#include <errno.h>
>>>>> +#include "openvswitch/util.h"
>>>>> +#include "openvswitch/hmap.h"
>>>>> +#include "openvswitch/thread.h"
>>>>> +#include "ovs-atomic.h"
>>>>> +
>>>>> +/* Process this include only if OVS does not supply parallel definitions
>>>>> + */
>>>>> +
>>>>> +#ifdef OVS_HAS_PARALLEL_HMAP
>>>>> +
>>>>> +#include "parallel-hmap.h"
>>>>> +
>>>>> +#else
>>>>> +
>>>>> +
>>>>> +#ifdef __clang__
>>>>> +#pragma clang diagnostic push
>>>>> +#pragma clang diagnostic ignored "-Wthread-safety"
>>>>> +#endif
>>>>> +
>>>>> +
>>>>> +/* A version of the HMAP_FOR_EACH macro intended for iterating as part
>>>>> + * of parallel processing.
>>>>> + * Each worker thread has a different ThreadID in the range of 0..POOL_SIZE
>>>>> + * and will iterate hash buckets ThreadID, ThreadID + step,
>>>>> + * ThreadID + step * 2, etc. The actual macro accepts
>>>>> + * ThreadID + step * i as the JOBID parameter.
>>>>> + */
>>>>> +
>>>>> +#define HMAP_FOR_EACH_IN_PARALLEL(NODE, MEMBER, JOBID, HMAP) \
>>>>> + for (INIT_CONTAINER(NODE, hmap_first_in_bucket_num(HMAP, JOBID), MEMBER); \
>>>>> + (NODE != OBJECT_CONTAINING(NULL, NODE, MEMBER)) \
>>>>> + || ((NODE = NULL), false); \
>>>>> + ASSIGN_CONTAINER(NODE, hmap_next_in_bucket(&(NODE)->MEMBER), MEMBER))
>>>>> +
>>>>> +/* We do not have a SAFE version of the macro, because the hash size is not
>>>>> + * atomic and hash removal operations would need to be wrapped with
>>>>> + * locks. This will defeat most of the benefits from doing anything in
>>>>> + * parallel.
>>>>> + * If the code block inside FOR_EACH_IN_PARALLEL needs to remove elements,
>>>>> + * each thread should store them in a temporary list result instead, merging
>>>>> + * the lists into a combined result at the end */
>>>>> +
>>>>> +/* Work "Handle" */
>>>>> +
>>>>> +struct worker_control {
>>>>> + int id; /* Used as a modulo when iterating over a hash. */
>>>>> + atomic_bool finished; /* Set to true after achunk of work is complete. */
>>>>> + sem_t *fire; /* Work start semaphore - sem_post starts the worker. */
>>>>> + sem_t *done; /* Work completion semaphore - sem_post on completion. */
>>>>> + struct ovs_mutex mutex; /* Guards the data. */
>>>>> + void *data; /* Pointer to data to be processed. */
>>>>> + void *workload; /* back-pointer to the worker pool structure. */
>>>>> +};
>>>>> +
>>>>> +struct worker_pool {
>>>>> + int size; /* Number of threads in the pool. */
>>>>> + struct ovs_list list_node; /* List of pools - used in cleanup/exit. */
>>>>> + struct worker_control *controls; /* "Handles" in this pool. */
>>>>> + sem_t *done; /* Work completion semaphorew. */
>>>>> +};
>>>>> +
>>>>> +/* Add a worker pool for thread function start() which expects a pointer to
>>>>> + * a worker_control structure as an argument. */
>>>>> +
>>>>> +struct worker_pool *ovn_add_worker_pool(void *(*start)(void *));
>>>>> +
>>>>> +/* Setting this to true will make all processing threads exit */
>>>>> +
>>>>> +bool ovn_stop_parallel_processing(void);
>>>>> +
>>>>> +/* Build a hmap pre-sized for size elements */
>>>>> +
>>>>> +void ovn_fast_hmap_size_for(struct hmap *hmap, int size);
>>>>> +
>>>>> +/* Build a hmap with a mask equals to size */
>>>>> +
>>>>> +void ovn_fast_hmap_init(struct hmap *hmap, ssize_t size);
>>>>> +
>>>>> +/* Brute-force merge a hmap into hmap.
>>>>> + * Dest and inc have to have the same mask. The merge is performed
>>>>> + * by extending the element list for bucket N in the dest hmap with the list
>>>>> + * from bucket N in inc.
>>>>> + */
>>>>> +
>>>>> +void ovn_fast_hmap_merge(struct hmap *dest, struct hmap *inc);
>>>>> +
>>>>> +/* Run a pool, without any default processing of results.
>>>>> + */
>>>>> +
>>>>> +void ovn_run_pool(struct worker_pool *pool);
>>>>> +
>>>>> +/* Run a pool, merge results from hash frags into a final hash result.
>>>>> + * The hash frags must be pre-sized to the same size.
>>>>> + */
>>>>> +
>>>>> +void ovn_run_pool_hash(struct worker_pool *pool,
>>>>> + struct hmap *result, struct hmap *result_frags);
>>>>> +/* Run a pool, merge results from list frags into a final list result.
>>>>> + */
>>>>> +
>>>>> +void ovn_run_pool_list(struct worker_pool *pool,
>>>>> + struct ovs_list *result, struct ovs_list *result_frags);
>>>>> +
>>>>> +/* Run a pool, call a callback function to perform processing of results.
>>>>> + */
>>>>> +
>>>>> +void ovn_run_pool_callback(struct worker_pool *pool, void *fin_result,
>>>>> + void *result_frags,
>>>>> + void (*helper_func)(struct worker_pool *pool,
>>>>> + void *fin_result, void *result_frags, int index));
>>>>> +
>>>>> +
>>>>> +/* Returns the first node in 'hmap' in the bucket in which the given 'hash'
>>>>> + * would land, or a null pointer if that bucket is empty. */
>>>>> +
>>>>> +static inline struct hmap_node *
>>>>> +hmap_first_in_bucket_num(const struct hmap *hmap, size_t num)
>>>>> +{
>>>>> + return hmap->buckets[num];
>>>>> +}
>>>>> +
>>>>> +static inline struct hmap_node *
>>>>> +parallel_hmap_next__(const struct hmap *hmap, size_t start, size_t pool_size)
>>>>> +{
>>>>> + size_t i;
>>>>> + for (i = start; i <= hmap->mask; i+= pool_size) {
>>>>> + struct hmap_node *node = hmap->buckets[i];
>>>>> + if (node) {
>>>>> + return node;
>>>>> + }
>>>>> + }
>>>>> + return NULL;
>>>>> +}
>>>>> +
>>>>> +/* Returns the first node in 'hmap', as expected by thread with job_id
>>>>> + * for parallel processing in arbitrary order, or a null pointer if
>>>>> + * the slice of 'hmap' for that job_id is empty. */
>>>>> +static inline struct hmap_node *
>>>>> +parallel_hmap_first(const struct hmap *hmap, size_t job_id, size_t pool_size)
>>>>> +{
>>>>> + return parallel_hmap_next__(hmap, job_id, pool_size);
>>>>> +}
>>>>> +
>>>>> +/* Returns the next node in the slice of 'hmap' following 'node',
>>>>> + * in arbitrary order, or a * null pointer if 'node' is the last node in
>>>>> + * the 'hmap' slice.
>>>>> + *
>>>>> + */
>>>>> +static inline struct hmap_node *
>>>>> +parallel_hmap_next(const struct hmap *hmap,
>>>>> + const struct hmap_node *node, ssize_t pool_size)
>>>>> +{
>>>>> + return (node->next
>>>>> + ? node->next
>>>>> + : parallel_hmap_next__(hmap,
>>>>> + (node->hash & hmap->mask) + pool_size, pool_size));
>>>>> +}
>>>>> +
>>>>> +static inline void post_completed_work(struct worker_control *control)
>>>>> +{
>>>>> + atomic_thread_fence(memory_order_acq_rel);
>>>>> + atomic_store_relaxed(&control->finished, true);
>>>>> + sem_post(control->done);
>>>>> +}
>>>>> +
>>>>> +static inline void wait_for_work(struct worker_control *control)
>>>>> +{
>>>>> + int ret;
>>>>> +
>>>>> + do {
>>>>> + ret = sem_wait(control->fire);
>>>>> + } while ((ret == -1) && (errno == EINTR));
>>>>> + ovs_assert(ret == 0);
>>>>> +}
>>>>> +static inline void wait_for_work_completion(struct worker_pool *pool)
>>>>> +{
>>>>> + int ret;
>>>>> +
>>>>> + do {
>>>>> + ret = sem_wait(pool->done);
>>>>> + } while ((ret == -1) && (errno == EINTR));
>>>>> + ovs_assert(ret == 0);
>>>>> +}
>>>>> +
>>>>> +
>>>>> +/* Hash per-row locking support - to be used only in conjunction
>>>>> + * with fast hash inserts. Normal hash inserts may resize the hash
>>>>> + * rendering the locking invalid.
>>>>> + */
>>>>> +
>>>>> +struct hashrow_locks {
>>>>> + ssize_t mask;
>>>>> + struct ovs_mutex *row_locks;
>>>>> +};
>>>>> +
>>>>> +/* Update an hash row locks structure to match the current hash size */
>>>>> +
>>>>> +void ovn_update_hashrow_locks(struct hmap *lflows, struct hashrow_locks *hrl);
>>>>> +
>>>>> +/* Lock a hash row */
>>>>> +
>>>>> +static inline void lock_hash_row(struct hashrow_locks *hrl, uint32_t hash)
>>>>> +{
>>>>> + ovs_mutex_lock(&hrl->row_locks[hash % hrl->mask]);
>>>>> +}
>>>>> +
>>>>> +/* Unlock a hash row */
>>>>> +
>>>>> +static inline void unlock_hash_row(struct hashrow_locks *hrl, uint32_t hash)
>>>>> +{
>>>>> + ovs_mutex_unlock(&hrl->row_locks[hash % hrl->mask]);
>>>>> +}
>>>>> +/* Init the row locks structure */
>>>>> +
>>>>> +static inline void init_hash_row_locks(struct hashrow_locks *hrl)
>>>>> +{
>>>>> + hrl->mask = 0;
>>>>> + hrl->row_locks = NULL;
>>>>> +}
>>>>> +
>>>>> +bool ovn_can_parallelize_hashes(bool force_parallel);
>>>>> +
>>>>> +/* Use the OVN library functions for stuff which OVS has not defined
>>>>> + * If OVS has defined these, they will still compile using the OVN
>>>>> + * local names, but will be dropped by the linker in favour of the OVS
>>>>> + * supplied functions.
>>>>> + */
>>>>> +
>>>>> +#define update_hashrow_locks(lflows, hrl) ovn_update_hashrow_locks(lflows, hrl)
>>>>> +
>>>>> +#define can_parallelize_hashes(force) ovn_can_parallelize_hashes(force)
>>>>> +
>>>>> +#define stop_parallel_processing() ovn_stop_parallel_processing()
>>>>> +
>>>>> +#define add_worker_pool(start) ovn_add_worker_pool(start)
>>>>> +
>>>>> +#define fast_hmap_size_for(hmap, size) ovn_fast_hmap_size_for(hmap, size)
>>>>> +
>>>>> +#define fast_hmap_init(hmap, size) ovn_fast_hmap_init(hmap, size)
>>>>> +
>>>>> +#define fast_hmap_merge(dest, inc) ovn_fast_hmap_merge(dest, inc)
>>>>> +
>>>>> +#define hmap_merge(dest, inc) ovn_hmap_merge(dest, inc)
>>>>> +
>>>>> +#define ovn_run_pool(pool) ovn_run_pool(pool)
>>>>> +
>>>>> +#define run_pool_hash(pool, result, result_frags) \
>>>>> + ovn_run_pool_hash(pool, result, result_frags)
>>>>> +
>>>>> +#define run_pool_list(pool, result, result_frags) \
>>>>> + ovn_run_pool_list(pool, result, result_frags)
>>>>> +
>>>>> +#define run_pool_callback(pool, fin_result, result_frags, helper_func) \
>>>>> + ovn_run_pool_callback(pool, fin_result, result_frags, helper_func)
>>>>> +
>>>>> +
>>>>> +
>>>>> +#ifdef __clang__
>>>>> +#pragma clang diagnostic pop
>>>>> +#endif
>>>>> +
>>>>> +#endif
>>>>> +
>>>>> +#ifdef __cplusplus
>>>>> +}
>>>>> +#endif
>>>>> +
>>>>> +
>>>>> +#endif /* lib/fasthmap.h */
>>>>> --
>>>>> 2.20.1
>>>>>
>>>>> _______________________________________________
>>>>> dev mailing list
>>>>> dev at openvswitch.org
>>>>> https://mail.openvswitch.org/mailman/listinfo/ovs-dev
>>>>>
>>> --
>>> Anton R. Ivanov
>>> Cambridgegreys Limited. Registered in England. Company Number 10273661
>>> https://www.cambridgegreys.com/
>>> _______________________________________________
>>> dev mailing list
>>> dev at openvswitch.org
>>> https://mail.openvswitch.org/mailman/listinfo/ovs-dev
>>>
>
--
Anton R. Ivanov
Cambridgegreys Limited. Registered in England. Company Number 10273661
https://www.cambridgegreys.com/
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