From: Aneesh Kumar K.V <aneesh.ku...@linux.vnet.ibm.com> This patch creates a generic asynchronous-task-offloading infrastructure. It's extracted out of the threading framework that is being used by paio.
The reason for extracting out this generic infrastructure of the posix-aio-compat.c is so that other subsystems, such as virtio-9p could make use of it for offloading tasks that could block. [...@in.ibm.com: work_item_pool, async_work_init, async_work_release, async_cancel_work] Signed-off-by: Aneesh Kumar K.V <aneesh.ku...@linux.vnet.ibm.com> Signed-off-by: Gautham R Shenoy <e...@in.ibm.com> --- Makefile.objs | 3 + async-work.c | 136 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++ async-work.h | 85 ++++++++++++++++++++++++++++++++++++ 3 files changed, 223 insertions(+), 1 deletions(-) create mode 100644 async-work.c create mode 100644 async-work.h diff --git a/Makefile.objs b/Makefile.objs index ecdd53e..fd5ea4d 100644 --- a/Makefile.objs +++ b/Makefile.objs @@ -9,6 +9,8 @@ qobject-obj-y += qerror.o block-obj-y = cutils.o cache-utils.o qemu-malloc.o qemu-option.o module.o block-obj-y += nbd.o block.o aio.o aes.o osdep.o qemu-config.o +block-obj-y += qemu-thread.o +block-obj-y += async-work.o block-obj-$(CONFIG_POSIX) += posix-aio-compat.o block-obj-$(CONFIG_LINUX_AIO) += linux-aio.o @@ -108,7 +110,6 @@ common-obj-y += iov.o common-obj-$(CONFIG_VNC_TLS) += vnc-tls.o vnc-auth-vencrypt.o common-obj-$(CONFIG_VNC_SASL) += vnc-auth-sasl.o common-obj-$(CONFIG_COCOA) += cocoa.o -common-obj-$(CONFIG_IOTHREAD) += qemu-thread.o common-obj-y += notify.o event_notifier.o common-obj-y += qemu-timer.o diff --git a/async-work.c b/async-work.c new file mode 100644 index 0000000..0675732 --- /dev/null +++ b/async-work.c @@ -0,0 +1,136 @@ +/* + * Async work support + * + * Copyright IBM, Corp. 2010 + * + * Authors: + * Aneesh Kumar K.V <aneesh.ku...@linux.vnet.ibm.com> + * + * This work is licensed under the terms of the GNU GPL, version 2. See + * the COPYING file in the top-level directory. + * + */ +#include <stdio.h> +#include <errno.h> +#include <string.h> +#include <stdlib.h> +#include <signal.h> +#include "async-work.h" +#include "osdep.h" + +static void async_abort(int err, const char *what) +{ + fprintf(stderr, "%s failed: %s\n", what, strerror(err)); + abort(); +} + +static void *async_worker_thread(void *data) +{ + struct async_queue *queue = data; + + while (1) { + struct work_item *work; + int ret = 0; + qemu_mutex_lock(&(queue->lock)); + + while (QTAILQ_EMPTY(&(queue->request_list)) && + (ret != ETIMEDOUT)) { + ret = qemu_cond_timedwait(&(queue->cond), + &(queue->lock), 10*100000); + } + + if (QTAILQ_EMPTY(&(queue->request_list))) + goto check_exit; + + work = QTAILQ_FIRST(&(queue->request_list)); + QTAILQ_REMOVE(&(queue->request_list), work, node); + queue->idle_threads--; + qemu_mutex_unlock(&(queue->lock)); + + /* execute the work function */ + work->func(work); + async_work_release(queue, work); + + qemu_mutex_lock(&(queue->lock)); + queue->idle_threads++; + +check_exit: + if ((queue->idle_threads > 0) && + (queue->cur_threads > queue->min_threads)) { + /* we retain minimum number of threads */ + break; + } + qemu_mutex_unlock(&(queue->lock)); + } + + queue->idle_threads--; + queue->cur_threads--; + qemu_mutex_unlock(&(queue->lock)); + + return NULL; +} + +static void spawn_async_thread(struct async_queue *queue) +{ + QemuThreadAttr attr; + QemuThread thread; + sigset_t set, oldset; + + queue->cur_threads++; + queue->idle_threads++; + + qemu_thread_attr_init(&attr); + + /* create a detached thread so that we don't need to wait on it */ + qemu_thread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED); + + /* block all signals */ + if (sigfillset(&set)) { + async_abort(errno, "sigfillset"); + } + + if (sigprocmask(SIG_SETMASK, &set, &oldset)) { + async_abort(errno, "sigprocmask"); + } + + qemu_thread_create_attr(&thread, &attr, async_worker_thread, queue); + + if (sigprocmask(SIG_SETMASK, &oldset, NULL)) { + async_abort(errno, "sigprocmask restore"); + } +} + +void qemu_async_submit(struct async_queue *queue, struct work_item *work) +{ + qemu_mutex_lock(&(queue->lock)); + if (queue->idle_threads == 0 && queue->cur_threads < queue->max_threads) { + spawn_async_thread(queue); + } + QTAILQ_INSERT_TAIL(&(queue->request_list), work, node); + qemu_mutex_unlock(&(queue->lock)); + qemu_cond_signal(&(queue->cond)); +} + +int qemu_async_cancel_work(struct async_queue *queue, struct work_item *work) +{ + struct work_item *ret_work; + int found = 0; + + qemu_mutex_lock(&(queue->lock)); + QTAILQ_FOREACH(ret_work, &(queue->request_list), node) { + if (ret_work == work) { + QTAILQ_REMOVE(&(queue->request_list), ret_work, node); + found = 1; + break; + } + } + qemu_mutex_unlock(&(queue->lock)); + + if (found) { + async_work_release(queue, work); + return 0; + } + + return 1; +} + diff --git a/async-work.h b/async-work.h new file mode 100644 index 0000000..8389f56 --- /dev/null +++ b/async-work.h @@ -0,0 +1,85 @@ +/* + * Async work support + * + * Copyright IBM, Corp. 2010 + * + * Authors: + * Aneesh Kumar K.V <aneesh.ku...@linux.vnet.ibm.com> + * + * This work is licensed under the terms of the GNU GPL, version 2. See + * the COPYING file in the top-level directory. + * + */ +#ifndef QEMU_ASYNC_WORK_H +#define QEMU_ASYNC_WORK_H + +#include "qemu-queue.h" +#include "qemu-common.h" +#include "qemu-thread.h" + +struct async_queue +{ + QemuMutex lock; + QemuCond cond; + int max_threads; + int min_threads; + int cur_threads; + int idle_threads; + QTAILQ_HEAD(, work_item) request_list; + QTAILQ_HEAD(, work_item) work_item_pool; +}; + +struct work_item +{ + QTAILQ_ENTRY(work_item) node; + void (*func)(struct work_item *work); + void *private; +}; + +static inline void async_queue_init(struct async_queue *queue, + int max_threads, int min_threads) +{ + queue->cur_threads = 0; + queue->idle_threads = 0; + queue->max_threads = max_threads; + queue->min_threads = min_threads; + QTAILQ_INIT(&(queue->request_list)); + QTAILQ_INIT(&(queue->work_item_pool)); + qemu_mutex_init(&(queue->lock)); + qemu_cond_init(&(queue->cond)); +} + +static inline struct work_item *async_work_init(struct async_queue *queue, + void (*func)(struct work_item *), + void *data) +{ + struct work_item *work; + qemu_mutex_lock(&(queue->lock)); + if (QTAILQ_EMPTY(&(queue->work_item_pool))) { + work = qemu_mallocz(sizeof(*work)); + } else { + work = QTAILQ_FIRST(&(queue->work_item_pool)); + QTAILQ_REMOVE(&(queue->work_item_pool), work, node); + } + + work->func = func; + work->private = data; + qemu_mutex_unlock(&(queue->lock)); + + return work; +} + +static inline void async_work_release(struct async_queue *queue, + struct work_item *work) +{ + qemu_mutex_lock(&(queue->lock)); + QTAILQ_INSERT_TAIL(&(queue->work_item_pool), work, node); + qemu_mutex_unlock(&(queue->lock)); +} + +extern void qemu_async_submit(struct async_queue *queue, + struct work_item *work); + +extern int qemu_async_cancel_work(struct async_queue *queue, + struct work_item *work); +#endif