On Thu, Jan 14, 2021 at 10:12 PM <anton.iva...@cambridgegreys.com> wrote:
> From: Anton Ivanov <anton.iva...@cambridgegreys.com> > > This adds a set of functions and macros intended to process > hashes in parallel. > > The principles of operation are documented in the fasthmap.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.iva...@cambridgegreys.com> > --- > Hi Anton, I tested v10 of your series and I found some interesting results. --------- ------------------------------------------------------------------------------------------------ | DP groups | Parallel hmaps | ovn_db_run time in sec | No of lflows | ------------------------------------------------------------------------------------------------ | NO | NO | ~13.5 | 1499325 | ------------------------------------------------------------------------------------------------ | NO | YES | ~9.7 | 1499325 | ------------------------------------------------------------------------------------------------ | YES | NO | ~3.1 | 123360 | ------------------------------------------------------------------------------------------------ | YES | YES | ~1.1 | 123360 | ------------------------------------------------------------------------------------------------ I see huge improvement with dp groups enabled and parallel processing enabled. Did you see the same behavior ? I ran the test on Intel(R) Xeon(R) Gold 5218 CPU @ 2.30GHz with 64 cores with ~180GB RAM. Few small nit comments below Thanks Numan lib/automake.mk | 2 + > lib/fasthmap.c | 326 ++++++++++++++++++++++++++++++++++++++++++++++++ > lib/fasthmap.h | 206 ++++++++++++++++++++++++++++++ > 3 files changed, 534 insertions(+) > create mode 100644 lib/fasthmap.c > create mode 100644 lib/fasthmap.h > > diff --git a/lib/automake.mk b/lib/automake.mk > index 250c7aefa..d7e4b20cf 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/fasthmap.h \ > + lib/fasthmap.c \ > lib/ip-mcast-index.c \ > lib/ip-mcast-index.h \ > lib/mcast-group-index.c \ > diff --git a/lib/fasthmap.c b/lib/fasthmap.c > new file mode 100644 > index 000000000..2be93e6a8 > --- /dev/null > +++ b/lib/fasthmap.c > @@ -0,0 +1,326 @@ > +/* > + * 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 <unistd.h> > +#include <semaphore.h> > +#include "fatal-signal.h" > +#include "util.h" > +#include "openvswitch/vlog.h" > +#include "openvswitch/hmap.h" > +#include "openvswitch/thread.h" > +#include "fasthmap.h" > +#include "ovs-atomic.h" > +#include "ovs-thread.h" > +#include "ovs-numa.h" > + > +VLOG_DEFINE_THIS_MODULE(fasthmap); > + > + > +/* These are accessed under mutex inside ovn_add_worker_pool(). > + * They do not need to be atomic. > + */ > + > +static bool worker_pool_setup = 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 void worker_pool_hook(void *aux OVS_UNUSED) { > + int i; > + static struct worker_pool *pool; > + 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); > + } > + } > +} > + > +static void setup_worker_pools(void) { > + 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 > 16) { > + pool_size = 16; > + } > + can_parallelize = (pool_size >= 3); > + fatal_signal_add_hook(worker_pool_hook, NULL, NULL, true); > +} > + > +bool ovn_cease_fire(void) > This function name seems a bit odd to me ? Can it be renamed to a better name ? May be ovn_abort_pool() ? > +{ > + return workers_must_exit; > +} > + > +struct worker_pool *ovn_add_worker_pool(void *(*start)(void *)){ > + > + struct worker_pool *new_pool = NULL; > + struct worker_control *new_control; > + int i; > + > + ovs_mutex_lock(&init_mutex); > + > + if (!worker_pool_setup) { > + setup_worker_pools(); > + worker_pool_setup = true; > + } > + > + if (can_parallelize) { > + new_pool = xmalloc(sizeof(struct worker_pool)); > + new_pool->size = pool_size; > + sem_init(&new_pool->done, 0, 0); > + > + ovs_list_push_back(&worker_pools, &new_pool->list_node); > + > + 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]; > + sem_init(&new_control->fire, 0, 0); > + 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); > + } > + > + for (i = 0; i < pool_size; i++) { > + ovs_thread_create("worker pool helper", start, > &new_pool->controls[i]); > + } > + } > + ovs_mutex_unlock(&init_mutex); > + return new_pool; > +} > + > + > +/* 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)) > Indentation seems a bit odd to me in many places. Can the function parameters be aligned properly like the rest of the existing code ? > +{ > + 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. > + */ > + sem_wait(&pool->done); > + 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) > +{ > + ovn_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. > + */ > + > +static void merge_hash_results(struct worker_pool *pool OVS_UNUSED, > + void *fin_result, void *result_frags, int index) > Same here. Can you please move the fin_result param and align with the first param in the first line ? Like 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]); > +} > + > + > +void ovn_run_pool_hash( > + struct worker_pool *pool, > + struct hmap *result, > + struct hmap *result_frags) > +{ > + ovn_run_pool_callback(pool, result, result_frags, merge_hash_results); > +} > diff --git a/lib/fasthmap.h b/lib/fasthmap.h > new file mode 100644 > index 000000000..2a28553d5 > --- /dev/null > +++ b/lib/fasthmap.h > @@ -0,0 +1,206 @@ > +/* > + * 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 > + > +/* Process this include only if OVS does not supply parallel definitions > + */ > + > +#ifndef OVS_HAS_PARALLEL_HMAP > + > +/* 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 "openvswitch/util.h" > +#include "openvswitch/hmap.h" > +#include "openvswitch/thread.h" > +#include "ovs-atomic.h" > + > +/* 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_cease_fire(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, 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)); > +} > + > +/* 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 cease_fire() ovn_cease_fire() > + > +#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_callback(pool, fin_result, result_frags, helper_func) \ > + ovn_run_pool_callback(pool, fin_result, result_frags, helper_func) > + > +#ifdef __cplusplus > +} > +#endif > + > +#endif > + > +#endif /* lib/fasthmap.h */ > -- > 2.20.1 > > _______________________________________________ > dev mailing list > d...@openvswitch.org > https://mail.openvswitch.org/mailman/listinfo/ovs-dev > > _______________________________________________ dev mailing list d...@openvswitch.org https://mail.openvswitch.org/mailman/listinfo/ovs-dev