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 | 2 +
async-work.c | 152 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
async-work.h | 85 ++++++++++++++++++++++++++++++++
3 files changed, 239 insertions(+), 0 deletions(-)
create mode 100644 async-work.c
create mode 100644 async-work.h
diff --git a/Makefile.objs b/Makefile.objs
index ecdd53e..faf3d67 100644
--- a/Makefile.objs
+++ b/Makefile.objs
@@ -9,6 +9,7 @@ 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 += async-work.o
block-obj-$(CONFIG_POSIX) += posix-aio-compat.o
block-obj-$(CONFIG_LINUX_AIO) += linux-aio.o
@@ -44,6 +45,7 @@ fsdev-obj-$(CONFIG_LINUX) += $(addprefix fsdev/,
$(fsdev-nested-y))
# system emulation, i.e. a single QEMU executable should support all
# CPUs and machines.
+#common-obj-y = $(asyncwork-obj-y)
common-obj-y = $(block-obj-y)
common-obj-y += $(net-obj-y)
common-obj-y += $(qobject-obj-y)
diff --git a/async-work.c b/async-work.c
new file mode 100644
index 0000000..5195bbf
--- /dev/null
+++ b/async-work.c
@@ -0,0 +1,152 @@
+/*
+ * 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_timeval tv;
+ struct timespec ts;
+
+ qemu_gettimeofday(&tv);
+ ts.tv_sec = tv.tv_sec + 10;
+ ts.tv_nsec = 0;
+
+ pthread_mutex_lock(&(queue->lock));
+
+ while (QTAILQ_EMPTY(&(queue->request_list)) &&
+ (ret != ETIMEDOUT)) {
+ ret = pthread_cond_timedwait(&(queue->cond),
+ &(queue->lock), &ts);
+ }
+
+ 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--;
+ pthread_mutex_unlock(&(queue->lock));
+
+ /* execute the work function */
+ work->func(work);
+ async_work_release(queue, work);
+
+ pthread_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;
+ }
+ pthread_mutex_unlock(&(queue->lock));
+ }
+
+ queue->idle_threads--;
+ queue->cur_threads--;
+ pthread_mutex_unlock(&(queue->lock));
+
+ return NULL;
+}
+
+static void spawn_async_thread(struct async_queue *queue)
+{
+ int ret;
+ pthread_attr_t attr;
+ pthread_t thread_id;
+ sigset_t set, oldset;
+
+ queue->cur_threads++;
+ queue->idle_threads++;
+ ret = pthread_attr_init(&attr);
+ if (ret) {
+ async_abort(ret, "pthread_attr_init");
+ }
+
+ /* create a detached thread so that we don't need to wait on it */
+ ret = pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
+ if (ret) {
+ async_abort(ret, "pthread_attr_setdetachstate");
+ }
+
+ /* block all signals */
+ if (sigfillset(&set)) {
+ async_abort(errno, "sigfillset");
+ }
+
+ if (sigprocmask(SIG_SETMASK, &set, &oldset)) {
+ async_abort(errno, "sigprocmask");
+ }
+
+ ret = pthread_create(&thread_id, &attr, async_worker_thread, queue);
+ if (ret) {
+ async_abort(ret, "pthread_create");
+ }
+
+ if (sigprocmask(SIG_SETMASK, &oldset, NULL)) {
+ async_abort(errno, "sigprocmask restore");
+ }
+}
+
+void qemu_async_submit(struct async_queue *queue, struct work_item *work)
+{
+ pthread_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);
+ pthread_mutex_unlock(&(queue->lock));
+ pthread_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;
+
+ pthread_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;
+ }
+ }
+ pthread_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..eef60f7
--- /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 <pthread.h>
+#include "qemu-queue.h"
+#include "qemu-common.h"
+
+struct async_queue
+{
+ pthread_mutex_t lock;
+ pthread_cond_t 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));
+ pthread_mutex_init(&(queue->lock), NULL);
+ pthread_cond_init(&(queue->cond), NULL);
+}
+
+static inline struct work_item *async_work_init(struct async_queue *queue,
+ void (*func)(struct work_item *),
+ void *data)
+{
+ struct work_item *work;
+ pthread_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;
+ pthread_mutex_unlock(&(queue->lock));
+
+ return work;
+}
+
+static inline void async_work_release(struct async_queue *queue,
+ struct work_item *work)
+{
+ pthread_mutex_lock(&(queue->lock));
+ QTAILQ_INSERT_TAIL(&(queue->work_item_pool), work, node);
+ pthread_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
