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-rw-r--r--qemu/thread-pool.c343
1 files changed, 0 insertions, 343 deletions
diff --git a/qemu/thread-pool.c b/qemu/thread-pool.c
deleted file mode 100644
index 03ba0b02a..000000000
--- a/qemu/thread-pool.c
+++ /dev/null
@@ -1,343 +0,0 @@
-/*
- * QEMU block layer thread pool
- *
- * Copyright IBM, Corp. 2008
- * Copyright Red Hat, Inc. 2012
- *
- * Authors:
- * Anthony Liguori <aliguori@us.ibm.com>
- * Paolo Bonzini <pbonzini@redhat.com>
- *
- * This work is licensed under the terms of the GNU GPL, version 2. See
- * the COPYING file in the top-level directory.
- *
- * Contributions after 2012-01-13 are licensed under the terms of the
- * GNU GPL, version 2 or (at your option) any later version.
- */
-#include "qemu/osdep.h"
-#include "qemu-common.h"
-#include "qemu/queue.h"
-#include "qemu/thread.h"
-#include "qemu/coroutine.h"
-#include "trace.h"
-#include "block/thread-pool.h"
-#include "qemu/main-loop.h"
-
-static void do_spawn_thread(ThreadPool *pool);
-
-typedef struct ThreadPoolElement ThreadPoolElement;
-
-enum ThreadState {
- THREAD_QUEUED,
- THREAD_ACTIVE,
- THREAD_DONE,
-};
-
-struct ThreadPoolElement {
- BlockAIOCB common;
- ThreadPool *pool;
- ThreadPoolFunc *func;
- void *arg;
-
- /* Moving state out of THREAD_QUEUED is protected by lock. After
- * that, only the worker thread can write to it. Reads and writes
- * of state and ret are ordered with memory barriers.
- */
- enum ThreadState state;
- int ret;
-
- /* Access to this list is protected by lock. */
- QTAILQ_ENTRY(ThreadPoolElement) reqs;
-
- /* Access to this list is protected by the global mutex. */
- QLIST_ENTRY(ThreadPoolElement) all;
-};
-
-struct ThreadPool {
- AioContext *ctx;
- QEMUBH *completion_bh;
- QemuMutex lock;
- QemuCond worker_stopped;
- QemuSemaphore sem;
- int max_threads;
- QEMUBH *new_thread_bh;
-
- /* The following variables are only accessed from one AioContext. */
- QLIST_HEAD(, ThreadPoolElement) head;
-
- /* The following variables are protected by lock. */
- QTAILQ_HEAD(, ThreadPoolElement) request_list;
- int cur_threads;
- int idle_threads;
- int new_threads; /* backlog of threads we need to create */
- int pending_threads; /* threads created but not running yet */
- bool stopping;
-};
-
-static void *worker_thread(void *opaque)
-{
- ThreadPool *pool = opaque;
-
- qemu_mutex_lock(&pool->lock);
- pool->pending_threads--;
- do_spawn_thread(pool);
-
- while (!pool->stopping) {
- ThreadPoolElement *req;
- int ret;
-
- do {
- pool->idle_threads++;
- qemu_mutex_unlock(&pool->lock);
- ret = qemu_sem_timedwait(&pool->sem, 10000);
- qemu_mutex_lock(&pool->lock);
- pool->idle_threads--;
- } while (ret == -1 && !QTAILQ_EMPTY(&pool->request_list));
- if (ret == -1 || pool->stopping) {
- break;
- }
-
- req = QTAILQ_FIRST(&pool->request_list);
- QTAILQ_REMOVE(&pool->request_list, req, reqs);
- req->state = THREAD_ACTIVE;
- qemu_mutex_unlock(&pool->lock);
-
- ret = req->func(req->arg);
-
- req->ret = ret;
- /* Write ret before state. */
- smp_wmb();
- req->state = THREAD_DONE;
-
- qemu_mutex_lock(&pool->lock);
-
- qemu_bh_schedule(pool->completion_bh);
- }
-
- pool->cur_threads--;
- qemu_cond_signal(&pool->worker_stopped);
- qemu_mutex_unlock(&pool->lock);
- return NULL;
-}
-
-static void do_spawn_thread(ThreadPool *pool)
-{
- QemuThread t;
-
- /* Runs with lock taken. */
- if (!pool->new_threads) {
- return;
- }
-
- pool->new_threads--;
- pool->pending_threads++;
-
- qemu_thread_create(&t, "worker", worker_thread, pool, QEMU_THREAD_DETACHED);
-}
-
-static void spawn_thread_bh_fn(void *opaque)
-{
- ThreadPool *pool = opaque;
-
- qemu_mutex_lock(&pool->lock);
- do_spawn_thread(pool);
- qemu_mutex_unlock(&pool->lock);
-}
-
-static void spawn_thread(ThreadPool *pool)
-{
- pool->cur_threads++;
- pool->new_threads++;
- /* If there are threads being created, they will spawn new workers, so
- * we don't spend time creating many threads in a loop holding a mutex or
- * starving the current vcpu.
- *
- * If there are no idle threads, ask the main thread to create one, so we
- * inherit the correct affinity instead of the vcpu affinity.
- */
- if (!pool->pending_threads) {
- qemu_bh_schedule(pool->new_thread_bh);
- }
-}
-
-static void thread_pool_completion_bh(void *opaque)
-{
- ThreadPool *pool = opaque;
- ThreadPoolElement *elem, *next;
-
-restart:
- QLIST_FOREACH_SAFE(elem, &pool->head, all, next) {
- if (elem->state != THREAD_DONE) {
- continue;
- }
-
- trace_thread_pool_complete(pool, elem, elem->common.opaque,
- elem->ret);
- QLIST_REMOVE(elem, all);
-
- if (elem->common.cb) {
- /* Read state before ret. */
- smp_rmb();
-
- /* Schedule ourselves in case elem->common.cb() calls aio_poll() to
- * wait for another request that completed at the same time.
- */
- qemu_bh_schedule(pool->completion_bh);
-
- elem->common.cb(elem->common.opaque, elem->ret);
- qemu_aio_unref(elem);
- goto restart;
- } else {
- qemu_aio_unref(elem);
- }
- }
-}
-
-static void thread_pool_cancel(BlockAIOCB *acb)
-{
- ThreadPoolElement *elem = (ThreadPoolElement *)acb;
- ThreadPool *pool = elem->pool;
-
- trace_thread_pool_cancel(elem, elem->common.opaque);
-
- qemu_mutex_lock(&pool->lock);
- if (elem->state == THREAD_QUEUED &&
- /* No thread has yet started working on elem. we can try to "steal"
- * the item from the worker if we can get a signal from the
- * semaphore. Because this is non-blocking, we can do it with
- * the lock taken and ensure that elem will remain THREAD_QUEUED.
- */
- qemu_sem_timedwait(&pool->sem, 0) == 0) {
- QTAILQ_REMOVE(&pool->request_list, elem, reqs);
- qemu_bh_schedule(pool->completion_bh);
-
- elem->state = THREAD_DONE;
- elem->ret = -ECANCELED;
- }
-
- qemu_mutex_unlock(&pool->lock);
-}
-
-static AioContext *thread_pool_get_aio_context(BlockAIOCB *acb)
-{
- ThreadPoolElement *elem = (ThreadPoolElement *)acb;
- ThreadPool *pool = elem->pool;
- return pool->ctx;
-}
-
-static const AIOCBInfo thread_pool_aiocb_info = {
- .aiocb_size = sizeof(ThreadPoolElement),
- .cancel_async = thread_pool_cancel,
- .get_aio_context = thread_pool_get_aio_context,
-};
-
-BlockAIOCB *thread_pool_submit_aio(ThreadPool *pool,
- ThreadPoolFunc *func, void *arg,
- BlockCompletionFunc *cb, void *opaque)
-{
- ThreadPoolElement *req;
-
- req = qemu_aio_get(&thread_pool_aiocb_info, NULL, cb, opaque);
- req->func = func;
- req->arg = arg;
- req->state = THREAD_QUEUED;
- req->pool = pool;
-
- QLIST_INSERT_HEAD(&pool->head, req, all);
-
- trace_thread_pool_submit(pool, req, arg);
-
- qemu_mutex_lock(&pool->lock);
- if (pool->idle_threads == 0 && pool->cur_threads < pool->max_threads) {
- spawn_thread(pool);
- }
- QTAILQ_INSERT_TAIL(&pool->request_list, req, reqs);
- qemu_mutex_unlock(&pool->lock);
- qemu_sem_post(&pool->sem);
- return &req->common;
-}
-
-typedef struct ThreadPoolCo {
- Coroutine *co;
- int ret;
-} ThreadPoolCo;
-
-static void thread_pool_co_cb(void *opaque, int ret)
-{
- ThreadPoolCo *co = opaque;
-
- co->ret = ret;
- qemu_coroutine_enter(co->co, NULL);
-}
-
-int coroutine_fn thread_pool_submit_co(ThreadPool *pool, ThreadPoolFunc *func,
- void *arg)
-{
- ThreadPoolCo tpc = { .co = qemu_coroutine_self(), .ret = -EINPROGRESS };
- assert(qemu_in_coroutine());
- thread_pool_submit_aio(pool, func, arg, thread_pool_co_cb, &tpc);
- qemu_coroutine_yield();
- return tpc.ret;
-}
-
-void thread_pool_submit(ThreadPool *pool, ThreadPoolFunc *func, void *arg)
-{
- thread_pool_submit_aio(pool, func, arg, NULL, NULL);
-}
-
-static void thread_pool_init_one(ThreadPool *pool, AioContext *ctx)
-{
- if (!ctx) {
- ctx = qemu_get_aio_context();
- }
-
- memset(pool, 0, sizeof(*pool));
- pool->ctx = ctx;
- pool->completion_bh = aio_bh_new(ctx, thread_pool_completion_bh, pool);
- qemu_mutex_init(&pool->lock);
- qemu_cond_init(&pool->worker_stopped);
- qemu_sem_init(&pool->sem, 0);
- pool->max_threads = 64;
- pool->new_thread_bh = aio_bh_new(ctx, spawn_thread_bh_fn, pool);
-
- QLIST_INIT(&pool->head);
- QTAILQ_INIT(&pool->request_list);
-}
-
-ThreadPool *thread_pool_new(AioContext *ctx)
-{
- ThreadPool *pool = g_new(ThreadPool, 1);
- thread_pool_init_one(pool, ctx);
- return pool;
-}
-
-void thread_pool_free(ThreadPool *pool)
-{
- if (!pool) {
- return;
- }
-
- assert(QLIST_EMPTY(&pool->head));
-
- qemu_mutex_lock(&pool->lock);
-
- /* Stop new threads from spawning */
- qemu_bh_delete(pool->new_thread_bh);
- pool->cur_threads -= pool->new_threads;
- pool->new_threads = 0;
-
- /* Wait for worker threads to terminate */
- pool->stopping = true;
- while (pool->cur_threads > 0) {
- qemu_sem_post(&pool->sem);
- qemu_cond_wait(&pool->worker_stopped, &pool->lock);
- }
-
- qemu_mutex_unlock(&pool->lock);
-
- qemu_bh_delete(pool->completion_bh);
- qemu_sem_destroy(&pool->sem);
- qemu_cond_destroy(&pool->worker_stopped);
- qemu_mutex_destroy(&pool->lock);
- g_free(pool);
-}