[ovs-dev] [OVN Patch v15 1/3] ovn-libs: Add support for parallel processing
Numan Siddique
numans at ovn.org
Fri Mar 26 03:25:09 UTC 2021
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.
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
>
More information about the dev
mailing list