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Date: Fri, 2 Nov 2018 16:07:10 +0000
From: Vitaly Mayatskikh <v.mayatskih@...il.com>
To: "Michael S . Tsirkin" <mst@...hat.com>
Cc: Jason Wang <jasowang@...hat.com>, kvm@...r.kernel.org,
virtualization@...ts.linux-foundation.org, netdev@...r.kernel.org,
linux-kernel@...r.kernel.org,
Vitaly Mayatskikh <v.mayatskih@...il.com>
Subject: [PATCH 1/1] vhost: add per-vq worker thread
This enables a near linear scaling in multiqueue cases.
First virtqueue still gets the worker created unconditionally,
the rest is postponed until the actual poll starts on the queue.
Signed-off-by: Vitaly Mayatskikh <v.mayatskih@...il.com>
---
drivers/vhost/vhost.c | 123 +++++++++++++++++++++++++++++++-----------
drivers/vhost/vhost.h | 11 +++-
2 files changed, 100 insertions(+), 34 deletions(-)
diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index 3a5f81a66d34..523dcfac4541 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -185,18 +185,27 @@ void vhost_work_init(struct vhost_work *work, vhost_work_fn_t fn)
}
EXPORT_SYMBOL_GPL(vhost_work_init);
-/* Init poll structure */
-void vhost_poll_init(struct vhost_poll *poll, vhost_work_fn_t fn,
- __poll_t mask, struct vhost_dev *dev)
+
+static void vhost_vq_poll_init(struct vhost_poll *poll, vhost_work_fn_t fn,
+ __poll_t mask, struct vhost_virtqueue *vq)
{
init_waitqueue_func_entry(&poll->wait, vhost_poll_wakeup);
init_poll_funcptr(&poll->table, vhost_poll_func);
poll->mask = mask;
- poll->dev = dev;
+ poll->dev = vq->dev;
+ poll->vq = vq;
poll->wqh = NULL;
vhost_work_init(&poll->work, fn);
}
+EXPORT_SYMBOL_GPL(vhost_vq_poll_init);
+
+/* Init poll structure */
+void vhost_poll_init(struct vhost_poll *poll, vhost_work_fn_t fn,
+ __poll_t mask, struct vhost_dev *dev)
+{
+ vhost_vq_poll_init(poll, fn, mask, dev->vqs[0]);
+}
EXPORT_SYMBOL_GPL(vhost_poll_init);
/* Start polling a file. We add ourselves to file's wait queue. The caller must
@@ -232,31 +241,74 @@ void vhost_poll_stop(struct vhost_poll *poll)
}
EXPORT_SYMBOL_GPL(vhost_poll_stop);
-void vhost_work_flush(struct vhost_dev *dev, struct vhost_work *work)
+
+static void vhost_vq_poll_start_work(struct vhost_work *w)
+{
+ struct vhost_virtqueue *vq = container_of(w, struct vhost_virtqueue,
+ work);
+
+ vhost_poll_start(&vq->poll, vq->kick);
+}
+
+static int vhost_vq_worker(void *data);
+
+static int vhost_vq_poll_start(struct vhost_virtqueue *vq)
+{
+ if (!vq->worker) {
+ vq->worker = kthread_create(vhost_vq_worker, vq, "vhost-%d/%i",
+ vq->dev->pid, vq->index);
+ if (IS_ERR(vq->worker)) {
+ int ret = PTR_ERR(vq->worker);
+
+ pr_err("%s: can't create vq worker: %d\n", __func__,
+ ret);
+ vq->worker = NULL;
+ return ret;
+ }
+ }
+ vhost_work_init(&vq->work, vhost_vq_poll_start_work);
+ vhost_vq_work_queue(vq, &vq->work);
+ return 0;
+}
+
+static void vhost_vq_work_flush(struct vhost_virtqueue *vq,
+ struct vhost_work *work)
{
struct vhost_flush_struct flush;
- if (dev->worker) {
+ if (vq->worker) {
init_completion(&flush.wait_event);
vhost_work_init(&flush.work, vhost_flush_work);
- vhost_work_queue(dev, &flush.work);
+ vhost_vq_work_queue(vq, &flush.work);
wait_for_completion(&flush.wait_event);
}
}
+EXPORT_SYMBOL_GPL(vhost_vq_work_flush);
+
+void vhost_work_flush(struct vhost_dev *dev, struct vhost_work *work)
+{
+ vhost_vq_work_flush(dev->vqs[0], work);
+}
EXPORT_SYMBOL_GPL(vhost_work_flush);
/* Flush any work that has been scheduled. When calling this, don't hold any
* locks that are also used by the callback. */
void vhost_poll_flush(struct vhost_poll *poll)
{
- vhost_work_flush(poll->dev, &poll->work);
+ vhost_vq_work_flush(poll->vq, &poll->work);
}
EXPORT_SYMBOL_GPL(vhost_poll_flush);
void vhost_work_queue(struct vhost_dev *dev, struct vhost_work *work)
{
- if (!dev->worker)
+ return vhost_vq_work_queue(dev->vqs[0], work);
+}
+EXPORT_SYMBOL_GPL(vhost_work_queue);
+
+void vhost_vq_work_queue(struct vhost_virtqueue *vq, struct vhost_work *work)
+{
+ if (!vq->worker)
return;
if (!test_and_set_bit(VHOST_WORK_QUEUED, &work->flags)) {
@@ -264,22 +316,22 @@ void vhost_work_queue(struct vhost_dev *dev, struct vhost_work *work)
* sure it was not in the list.
* test_and_set_bit() implies a memory barrier.
*/
- llist_add(&work->node, &dev->work_list);
- wake_up_process(dev->worker);
+ llist_add(&work->node, &vq->work_list);
+ wake_up_process(vq->worker);
}
}
-EXPORT_SYMBOL_GPL(vhost_work_queue);
+EXPORT_SYMBOL_GPL(vhost_vq_work_queue);
/* A lockless hint for busy polling code to exit the loop */
bool vhost_has_work(struct vhost_dev *dev)
{
- return !llist_empty(&dev->work_list);
+ return !llist_empty(&dev->vqs[0]->work_list);
}
EXPORT_SYMBOL_GPL(vhost_has_work);
void vhost_poll_queue(struct vhost_poll *poll)
{
- vhost_work_queue(poll->dev, &poll->work);
+ vhost_vq_work_queue(poll->vq, &poll->work);
}
EXPORT_SYMBOL_GPL(vhost_poll_queue);
@@ -333,9 +385,10 @@ static void vhost_vq_reset(struct vhost_dev *dev,
__vhost_vq_meta_reset(vq);
}
-static int vhost_worker(void *data)
+static int vhost_vq_worker(void *data)
{
- struct vhost_dev *dev = data;
+ struct vhost_virtqueue *vq = data;
+ struct vhost_dev *dev = vq->dev;
struct vhost_work *work, *work_next;
struct llist_node *node;
mm_segment_t oldfs = get_fs();
@@ -351,8 +404,7 @@ static int vhost_worker(void *data)
__set_current_state(TASK_RUNNING);
break;
}
-
- node = llist_del_all(&dev->work_list);
+ node = llist_del_all(&vq->work_list);
if (!node)
schedule();
@@ -429,25 +481,26 @@ void vhost_dev_init(struct vhost_dev *dev,
dev->umem = NULL;
dev->iotlb = NULL;
dev->mm = NULL;
- dev->worker = NULL;
- init_llist_head(&dev->work_list);
init_waitqueue_head(&dev->wait);
INIT_LIST_HEAD(&dev->read_list);
INIT_LIST_HEAD(&dev->pending_list);
spin_lock_init(&dev->iotlb_lock);
-
for (i = 0; i < dev->nvqs; ++i) {
vq = dev->vqs[i];
+ vq->index = i;
vq->log = NULL;
vq->indirect = NULL;
vq->heads = NULL;
vq->dev = dev;
+ vq->worker = NULL;
mutex_init(&vq->mutex);
vhost_vq_reset(dev, vq);
+ init_llist_head(&vq->work_list);
+ vq->worker = NULL;
if (vq->handle_kick)
- vhost_poll_init(&vq->poll, vq->handle_kick,
- EPOLLIN, dev);
+ vhost_vq_poll_init(&vq->poll, vq->handle_kick,
+ EPOLLIN, vq);
}
}
EXPORT_SYMBOL_GPL(vhost_dev_init);
@@ -506,14 +559,16 @@ long vhost_dev_set_owner(struct vhost_dev *dev)
/* No owner, become one */
dev->mm = get_task_mm(current);
- worker = kthread_create(vhost_worker, dev, "vhost-%d", current->pid);
+ dev->pid = current->pid;
+ worker = kthread_create(vhost_vq_worker, dev->vqs[0], "vhost-%d/0",
+ current->pid);
if (IS_ERR(worker)) {
err = PTR_ERR(worker);
goto err_worker;
}
- dev->worker = worker;
- wake_up_process(worker); /* avoid contributing to loadavg */
+ dev->vqs[0]->worker = worker;
+ wake_up_process(worker); /* avoid contributing to loadavg */
err = vhost_attach_cgroups(dev);
if (err)
@@ -526,7 +581,7 @@ long vhost_dev_set_owner(struct vhost_dev *dev)
return 0;
err_cgroup:
kthread_stop(worker);
- dev->worker = NULL;
+ dev->vqs[0]->worker = NULL;
err_worker:
if (dev->mm)
mmput(dev->mm);
@@ -638,11 +693,15 @@ void vhost_dev_cleanup(struct vhost_dev *dev)
dev->iotlb = NULL;
vhost_clear_msg(dev);
wake_up_interruptible_poll(&dev->wait, EPOLLIN | EPOLLRDNORM);
- WARN_ON(!llist_empty(&dev->work_list));
- if (dev->worker) {
- kthread_stop(dev->worker);
- dev->worker = NULL;
+
+ for (i = 0; i < dev->nvqs; ++i) {
+ WARN_ON(!llist_empty(&dev->vqs[i]->work_list));
+ if (dev->vqs[i]->worker) {
+ kthread_stop(dev->vqs[i]->worker);
+ dev->vqs[i]->worker = NULL;
+ }
}
+
if (dev->mm)
mmput(dev->mm);
dev->mm = NULL;
@@ -1564,7 +1623,7 @@ long vhost_vring_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *arg
fput(filep);
if (pollstart && vq->handle_kick)
- r = vhost_poll_start(&vq->poll, vq->kick);
+ r = vhost_vq_poll_start(vq);
mutex_unlock(&vq->mutex);
diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h
index 466ef7542291..c00733fac49f 100644
--- a/drivers/vhost/vhost.h
+++ b/drivers/vhost/vhost.h
@@ -32,6 +32,7 @@ struct vhost_poll {
struct vhost_work work;
__poll_t mask;
struct vhost_dev *dev;
+ struct vhost_virtqueue *vq;
};
void vhost_work_init(struct vhost_work *work, vhost_work_fn_t fn);
@@ -86,6 +87,7 @@ struct vhost_virtqueue {
/* The actual ring of buffers. */
struct mutex mutex;
+ unsigned int index;
unsigned int num;
struct vring_desc __user *desc;
struct vring_avail __user *avail;
@@ -145,6 +147,10 @@ struct vhost_virtqueue {
bool user_be;
#endif
u32 busyloop_timeout;
+
+ struct llist_head work_list;
+ struct task_struct *worker;
+ struct vhost_work work;
};
struct vhost_msg_node {
@@ -158,12 +164,11 @@ struct vhost_msg_node {
struct vhost_dev {
struct mm_struct *mm;
+ pid_t pid;
struct mutex mutex;
struct vhost_virtqueue **vqs;
int nvqs;
struct eventfd_ctx *log_ctx;
- struct llist_head work_list;
- struct task_struct *worker;
struct vhost_umem *umem;
struct vhost_umem *iotlb;
spinlock_t iotlb_lock;
@@ -185,6 +190,8 @@ long vhost_vring_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *arg
bool vhost_vq_access_ok(struct vhost_virtqueue *vq);
bool vhost_log_access_ok(struct vhost_dev *);
+void vhost_vq_work_queue(struct vhost_virtqueue *vq, struct vhost_work *work);
+
int vhost_get_vq_desc(struct vhost_virtqueue *,
struct iovec iov[], unsigned int iov_count,
unsigned int *out_num, unsigned int *in_num,
--
2.17.1
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