CANN生态运行时核心:cann-runtime-core的任务调度策略
参考链接
cann组织链接:https://atomgit.com/cann
ops-nn仓库链接:https://atomgit.com/cann/ops-nn
引言
在AI应用的开发和部署过程中,任务调度是影响性能的关键因素。如何高效地调度计算任务、分配资源、优化执行顺序,直接影响AI应用的性能和资源利用率。CANN(Compute Architecture for Neural Networks)生态中的cann-runtime-core,作为运行时核心,提供了完善的任务调度策略。
本文将深入解析cann-runtime-core的任务调度策略,包括调度算法、资源分配和性能优化,旨在帮助开发者理解如何通过任务调度提高AI应用的性能。
一、任务调度概述
1.1 调度目标
任务调度的主要目标:
- 最大化吞吐量:最大化系统吞吐量
- 最小化延迟:最小化任务延迟
- 平衡负载:平衡不同设备的负载
- 提高资源利用率:提高资源利用率
1.2 调度类型
常见的任务调度类型:
- 先来先服务:先来先服务调度
- 最短作业优先:最短作业优先调度
- 优先级调度:优先级调度
- 公平调度:公平调度
二、调度算法
2.1 先来先服务
c
// 任务队列
typedef struct {
task_t* tasks;
int capacity;
int size;
int head;
int tail;
mutex_t mutex;
condition_t not_empty;
} task_queue_t;
// 创建任务队列
task_queue_t* create_task_queue(int capacity) {
task_queue_t* queue = (task_queue_t*)malloc(sizeof(task_queue_t));
if (queue == NULL) {
return NULL;
}
queue->tasks = (task_t*)malloc(capacity * sizeof(task_t));
if (queue->tasks == NULL) {
free(queue);
return NULL;
}
queue->capacity = capacity;
queue->size = 0;
queue->head = 0;
queue->tail = 0;
mutex_init(&queue->mutex);
condition_init(&queue->not_empty);
return queue;
}
// 提交任务
int submit_task(task_queue_t* queue, task_t* task) {
mutex_lock(&queue->mutex);
// 等待队列不满
while (queue->size >= queue->capacity) {
condition_wait(&queue->not_empty, &queue->mutex);
}
// 添加任务
queue->tasks[queue->tail] = *task;
queue->tail = (queue->tail + 1) % queue->capacity;
queue->size++;
// 通知有新任务
condition_signal(&queue->not_empty);
mutex_unlock(&queue->mutex);
return 0;
}
// 获取任务
int get_task(task_queue_t* queue, task_t* task) {
mutex_lock(&queue->mutex);
// 等待队列不空
while (queue->size <= 0) {
condition_wait(&queue->not_empty, &queue->mutex);
}
// 获取任务
*task = queue->tasks[queue->head];
queue->head = (queue->head + 1) % queue->capacity;
queue->size--;
// 通知队列不满
condition_signal(&queue->not_empty);
mutex_unlock(&queue->mutex);
return 0;
}
2.2 优先级调度
c
// 优先级任务队列
typedef struct {
task_t** tasks;
int capacity;
int size;
mutex_t mutex;
condition_t not_empty;
} priority_task_queue_t;
// 创建优先级任务队列
priority_task_queue_t* create_priority_task_queue(int capacity) {
priority_task_queue_t* queue = (priority_task_queue_t*)malloc(sizeof(priority_task_queue_t));
if (queue == NULL) {
return NULL;
}
queue->tasks = (task_t**)malloc(capacity * sizeof(task_t*));
if (queue->tasks == NULL) {
free(queue);
return NULL;
}
queue->capacity = capacity;
queue->size = 0;
mutex_init(&queue->mutex);
condition_init(&queue->not_empty);
return queue;
}
// 提交任务
int submit_priority_task(priority_task_queue_t* queue, task_t* task) {
mutex_lock(&queue->mutex);
// 等待队列不满
while (queue->size >= queue->capacity) {
condition_wait(&queue->not_empty, &queue->mutex);
}
// 添加任务(按优先级排序)
int i = queue->size;
while (i > 0 && queue->tasks[i - 1]->priority < task->priority) {
queue->tasks[i] = queue->tasks[i - 1];
i--;
}
queue->tasks[i] = task;
queue->size++;
// 通知有新任务
condition_signal(&queue->not_empty);
mutex_unlock(&queue->mutex);
return 0;
}
// 获取任务
int get_priority_task(priority_task_queue_t* queue, task_t* task) {
mutex_lock(&queue->mutex);
// 等待队列不空
while (queue->size <= 0) {
condition_wait(&queue->not_empty, &queue->mutex);
}
// 获取最高优先级任务
*task = *queue->tasks[queue->size - 1];
queue->size--;
// 通知队列不满
condition_signal(&queue->not_empty);
mutex_unlock(&queue->mutex);
return 0;
}
三、资源分配
3.1 动态资源分配
c
// 资源分配器
typedef struct {
int total_resources;
int allocated_resources;
int* resource_usage;
mutex_t mutex;
} resource_allocator_t;
// 创建资源分配器
resource_allocator_t* create_resource_allocator(int total_resources) {
resource_allocator_t* allocator = (resource_allocator_t*)malloc(sizeof(resource_allocator_t));
if (allocator == NULL) {
return NULL;
}
allocator->total_resources = total_resources;
allocator->allocated_resources = 0;
allocator->resource_usage = (int*)malloc(total_resources * sizeof(int));
for (int i = 0; i < total_resources; i++) {
allocator->resource_usage[i] = 0;
}
mutex_init(&allocator->mutex);
return allocator;
}
// 分配资源
int* allocate_resources(resource_allocator_t* allocator, int num_resources) {
mutex_lock(&allocator->mutex);
// 检查是否有足够资源
if (allocator->allocated_resources + num_resources > allocator->total_resources) {
mutex_unlock(&allocator->mutex);
return NULL;
}
// 分配资源
int* resources = (int*)malloc(num_resources * sizeof(int));
int allocated = 0;
for (int i = 0; i < allocator->total_resources && allocated < num_resources; i++) {
if (allocator->resource_usage[i] == 0) {
resources[allocated] = i;
allocator->resource_usage[i] = 1;
allocated++;
}
}
allocator->allocated_resources += num_resources;
mutex_unlock(&allocator->mutex);
return resources;
}
// 释放资源
void free_resources(resource_allocator_t* allocator, int* resources, int num_resources) {
mutex_lock(&allocator->mutex);
// 释放资源
for (int i = 0; i < num_resources; i++) {
allocator->resource_usage[resources[i]] = 0;
}
allocator->allocated_resources -= num_resources;
mutex_unlock(&allocator->mutex);
free(resources);
}
3.2 自适应资源分配
c
// 自适应资源分配器
typedef struct {
int total_resources;
int allocated_resources;
int* resource_usage;
float* task_priorities;
mutex_t mutex;
} adaptive_resource_allocator_t;
// 创建自适应资源分配器
adaptive_resource_allocator_t* create_adaptive_resource_allocator(int total_resources, int num_tasks) {
adaptive_resource_allocator_t* allocator = (adaptive_resource_allocator_t*)malloc(sizeof(adaptive_resource_allocator_t));
if (allocator == NULL) {
return NULL;
}
allocator->total_resources = total_resources;
allocator->allocated_resources = 0;
allocator->resource_usage = (int*)malloc(total_resources * sizeof(int));
allocator->task_priorities = (float*)malloc(num_tasks * sizeof(float));
for (int i = 0; i < total_resources; i++) {
allocator->resource_usage[i] = 0;
}
for (int i = 0; i < num_tasks; i++) {
allocator->task_priorities[i] = 1.0f;
}
mutex_init(&allocator->mutex);
return allocator;
}
// 分配资源
int* allocate_adaptive_resources(adaptive_resource_allocator_t* allocator, int task_id, int num_resources) {
mutex_lock(&allocator->mutex);
// 计算任务优先级
float priority = allocator->task_priorities[task_id];
int allocated_resources = (int)(priority * num_resources);
// 检查是否有足够资源
if (allocator->allocated_resources + allocated_resources > allocator->total_resources) {
mutex_unlock(&allocator->mutex);
return NULL;
}
// 分配资源
int* resources = (int*)malloc(allocated_resources * sizeof(int));
int allocated = 0;
for (int i = 0; i < allocator->total_resources && allocated < allocated_resources; i++) {
if (allocator->resource_usage[i] == 0) {
resources[allocated] = i;
allocator->resource_usage[i] = 1;
allocated++;
}
}
allocator->allocated_resources += allocated_resources;
mutex_unlock(&allocator->mutex);
return resources;
}
// 更新任务优先级
void update_task_priority(adaptive_resource_allocator_t* allocator, int task_id, float priority) {
mutex_lock(&allocator->mutex);
allocator->task_priorities[task_id] = priority;
mutex_unlock(&allocator->mutex);
}
四、性能优化
4.1 负载均衡
c
// 负载均衡器
typedef struct {
int num_workers;
int* worker_loads;
mutex_t mutex;
} load_balancer_t;
// 创建负载均衡器
load_balancer_t* create_load_balancer(int num_workers) {
load_balancer_t* balancer = (load_balancer_t*)malloc(sizeof(load_balancer_t));
if (balancer == NULL) {
return NULL;
}
balancer->num_workers = num_workers;
balancer->worker_loads = (int*)malloc(num_workers * sizeof(int));
for (int i = 0; i < num_workers; i++) {
balancer->worker_loads[i] = 0;
}
mutex_init(&balancer->mutex);
return balancer;
}
// 选择工作节点
int select_worker(load_balancer_t* balancer) {
mutex_lock(&balancer->mutex);
// 选择负载最低的工作节点
int selected_worker = 0;
int min_load = balancer->worker_loads[0];
for (int i = 1; i < balancer->num_workers; i++) {
if (balancer->worker_loads[i] < min_load) {
min_load = balancer->worker_loads[i];
selected_worker = i;
}
}
// 增加负载
balancer->worker_loads[selected_worker]++;
mutex_unlock(&balancer->mutex);
return selected_worker;
}
// 释放工作节点
void release_worker(load_balancer_t* balancer, int worker_id) {
mutex_lock(&balancer->mutex);
// 减少负载
balancer->worker_loads[worker_id]--;
mutex_unlock(&balancer->mutex);
}
4.2 任务窃取
c
// 任务窃取调度器
typedef struct {
task_queue_t** worker_queues;
int num_workers;
mutex_t mutex;
} work_stealing_scheduler_t;
// 创建任务窃取调度器
work_stealing_scheduler_t* create_work_stealing_scheduler(int num_workers, int queue_capacity) {
work_stealing_scheduler_t* scheduler = (work_stealing_scheduler_t*)malloc(sizeof(work_stealing_scheduler_t));
if (scheduler == NULL) {
return NULL;
}
scheduler->worker_queues = (task_queue_t**)malloc(num_workers * sizeof(task_queue_t*));
if (scheduler->worker_queues == NULL) {
free(scheduler);
return NULL;
}
// 创建工作队列
for (int i = 0; i < num_workers; i++) {
scheduler->worker_queues[i] = create_task_queue(queue_capacity);
}
scheduler->num_workers = num_workers;
mutex_init(&scheduler->mutex);
return scheduler;
}
// 获取任务(支持任务窃取)
int get_task_with_stealing(work_stealing_scheduler_t* scheduler, int worker_id, task_t* task) {
// 尝试从自己的队列获取任务
if (get_task(scheduler->worker_queues[worker_id], task) == 0) {
return 0;
}
// 尝试从其他工作节点窃取任务
for (int i = 0; i < scheduler->num_workers; i++) {
if (i != worker_id) {
if (get_task(scheduler->worker_queues[i], task) == 0) {
return 0;
}
}
}
return -1;
}
五、应用示例
5.1 任务调度
以下是一个使用cann-runtime-core进行任务调度的示例:
python
import cann_runtime_core as core
# 创建任务调度器
scheduler = core.TaskScheduler(
scheduling_policy='priority',
num_workers=4
)
# 提交任务
task = core.Task(
func=inference,
args=(model, input_data),
priority=1
)
scheduler.submit_task(task)
# 获取任务
task = scheduler.get_task()
# 执行任务
result = task.func(*task.args)
5.2 负载均衡
以下是一个使用cann-runtime-core进行负载均衡的示例:
python
import cann_runtime_core as core
# 创建负载均衡器
balancer = core.LoadBalancer(num_workers=4)
# 选择工作节点
worker_id = balancer.select_worker()
# 执行任务
result = execute_task_on_worker(worker_id, task)
# 释放工作节点
balancer.release_worker(worker_id)
六、最佳实践
6.1 调度策略选择
- 根据任务特点选择:根据任务特点选择合适的调度策略
- 根据资源限制选择:根据资源限制选择合适的调度策略
- 根据性能需求选择:根据性能需求选择合适的调度策略
- 根据公平性要求选择:根据公平性要求选择合适的调度策略
6.2 性能优化建议
- 使用负载均衡:使用负载均衡提高资源利用率
- 使用任务窃取:使用任务窃取提高并行度
- 优化任务粒度:优化任务粒度提高调度效率
- 使用自适应调度:使用自适应调度适应运行时状态
七、未来发展趋势
7.1 技术演进
- AI驱动的调度:利用AI技术优化任务调度
- 自适应调度:根据运行时状态自适应调整调度策略
- 预测性调度:基于历史数据预测任务执行时间
- 分布式调度:支持分布式任务调度
7.2 功能扩展
- 更多调度策略:支持更多调度策略
- 更灵活的配置:支持更灵活的调度配置
- 更完善的监控:提供更完善的任务调度监控
- 更智能的优化:提供更智能的调度优化建议
八、总结与建议
任务调度策略作为cann-runtime-core的核心功能,通过其完善的调度算法和资源分配能力,为AI应用提供了强大的任务调度支持。它不仅提高了资源利用率,还通过灵活的调度策略适应了不同的应用场景。
对于AI开发者来说,掌握任务调度的使用方法和最佳实践,可以显著提高AI应用的性能。在使用任务调度时,建议开发者:
- 根据任务特点选择:根据任务特点选择合适的调度策略
- 使用负载均衡:使用负载均衡提高资源利用率
- 使用任务窃取:使用任务窃取提高并行度
- 优化任务粒度:优化任务粒度提高调度效率
通过cann-runtime-core的任务调度策略,我们可以更加高效地调度计算任务,充分发挥硬件性能,为用户提供更加快速、高效的AI应用体验。
