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Date: Sun, 13 Oct 2013 21:55:43 -0400
From: Bandan Das <bsd@...hat.com>
To: kvm@...r.kernel.org
Cc: netdev@...r.kernel.org, Michael Tsirkin <mst@...hat.com>,
Jason Wang <jasowang@...hat.com>, Bandan Das <bsd@...efile.in>
Subject: [RFC PATCH v2 1/1] Workqueue based vhost workers
Signed-off-by: Bandan Das <bsd@...efile.in>
---
drivers/vhost/net.c | 25 +++++++++++
drivers/vhost/vhost.c | 115 +++++++++++++++++++++++++++++++++++++++++++-------
drivers/vhost/vhost.h | 6 +++
3 files changed, 130 insertions(+), 16 deletions(-)
diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
index 831eb4f..f5307d7 100644
--- a/drivers/vhost/net.c
+++ b/drivers/vhost/net.c
@@ -34,6 +34,10 @@ module_param(experimental_zcopytx, int, 0444);
MODULE_PARM_DESC(experimental_zcopytx, "Enable Zero Copy TX;"
" 1 -Enable; 0 - Disable");
+static int cmwq_worker;
+module_param(cmwq_worker, int, 0444);
+MODULE_PARM_DESC(cmwq_worker, "Use cmwq for worker threads - Experimental, 1 - Enable; 0 - Disable");
+
/* Max number of bytes transferred before requeueing the job.
* Using this limit prevents one virtqueue from starving others. */
#define VHOST_NET_WEIGHT 0x80000
@@ -694,6 +698,7 @@ static int vhost_net_open(struct inode *inode, struct file *f)
}
dev = &n->dev;
+ dev->use_wq = 0;
vqs[VHOST_NET_VQ_TX] = &n->vqs[VHOST_NET_VQ_TX].vq;
vqs[VHOST_NET_VQ_RX] = &n->vqs[VHOST_NET_VQ_RX].vq;
n->vqs[VHOST_NET_VQ_TX].vq.handle_kick = handle_tx_kick;
@@ -706,6 +711,10 @@ static int vhost_net_open(struct inode *inode, struct file *f)
n->vqs[i].vhost_hlen = 0;
n->vqs[i].sock_hlen = 0;
}
+
+ if (cmwq_worker)
+ dev->use_wq = 1;
+
r = vhost_dev_init(dev, vqs, VHOST_NET_VQ_MAX);
if (r < 0) {
kfree(n);
@@ -1123,14 +1132,30 @@ static struct miscdevice vhost_net_misc = {
static int vhost_net_init(void)
{
+ int ret = 0;
+
if (experimental_zcopytx)
vhost_net_enable_zcopy(VHOST_NET_VQ_TX);
+
+ if (cmwq_worker) {
+ ret = vhost_wq_init();
+ if (ret) {
+ pr_info("Enabling wq based vhost workers failed! "
+ "Switching to device based worker instead\n");
+ cmwq_worker = 0;
+ } else
+ pr_info("Enabled workqueues based vhost workers\n");
+ }
+
return misc_register(&vhost_net_misc);
}
module_init(vhost_net_init);
static void vhost_net_exit(void)
{
+ if (cmwq_worker)
+ vhost_wq_cleanup();
+
misc_deregister(&vhost_net_misc);
}
module_exit(vhost_net_exit);
diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index 69068e0..ba7ff7a 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -37,6 +37,9 @@ enum {
#define vhost_used_event(vq) ((u16 __user *)&vq->avail->ring[vq->num])
#define vhost_avail_event(vq) ((u16 __user *)&vq->used->ring[vq->num])
+static struct workqueue_struct *qworker;
+static void vhost_submission_workfn(struct work_struct *qwork);
+
static void vhost_poll_func(struct file *file, wait_queue_head_t *wqh,
poll_table *pt)
{
@@ -162,7 +165,10 @@ void vhost_work_queue(struct vhost_dev *dev, struct vhost_work *work)
list_add_tail(&work->node, &dev->work_list);
work->queue_seq++;
spin_unlock_irqrestore(&dev->work_lock, flags);
- wake_up_process(dev->worker);
+ if (dev->use_wq)
+ queue_work(qworker, &dev->qwork);
+ else
+ wake_up_process(dev->worker);
} else {
spin_unlock_irqrestore(&dev->work_lock, flags);
}
@@ -307,6 +313,9 @@ long vhost_dev_init(struct vhost_dev *dev,
INIT_LIST_HEAD(&dev->work_list);
dev->worker = NULL;
+ if (dev->use_wq)
+ INIT_WORK(&dev->qwork, vhost_submission_workfn);
+
for (i = 0; i < dev->nvqs; ++i) {
vq = dev->vqs[i];
vq->log = NULL;
@@ -367,7 +376,7 @@ EXPORT_SYMBOL_GPL(vhost_dev_has_owner);
/* Caller should have device mutex */
long vhost_dev_set_owner(struct vhost_dev *dev)
{
- struct task_struct *worker;
+ struct task_struct *worker = NULL;
int err;
/* Is there an owner already? */
@@ -376,28 +385,35 @@ long vhost_dev_set_owner(struct vhost_dev *dev)
goto err_mm;
}
+ err = vhost_dev_alloc_iovecs(dev);
+ if (err)
+ goto err_cgroup;
+
/* No owner, become one */
dev->mm = get_task_mm(current);
- worker = kthread_create(vhost_worker, dev, "vhost-%d", current->pid);
- if (IS_ERR(worker)) {
- err = PTR_ERR(worker);
- goto err_worker;
- }
- dev->worker = worker;
- wake_up_process(worker); /* avoid contributing to loadavg */
+ if (!dev->use_wq) {
+ worker = kthread_create(vhost_worker,
+ dev, "vhost-%d", current->pid);
+ if (IS_ERR(worker)) {
+ err = PTR_ERR(worker);
+ goto err_worker;
+ }
- err = vhost_attach_cgroups(dev);
- if (err)
- goto err_cgroup;
+ dev->worker = worker;
+ /* avoid contributing to loadavg */
+ wake_up_process(worker);
- err = vhost_dev_alloc_iovecs(dev);
- if (err)
- goto err_cgroup;
+ err = vhost_attach_cgroups(dev);
+ if (err)
+ goto err_cgroup;
+ } /* else don't worry, we are using wqs for vhost work */
return 0;
+
err_cgroup:
- kthread_stop(worker);
+ if (worker)
+ kthread_stop(worker);
dev->worker = NULL;
err_worker:
if (dev->mm)
@@ -1539,6 +1555,73 @@ void vhost_disable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
}
EXPORT_SYMBOL_GPL(vhost_disable_notify);
+static void vhost_submission_workfn(struct work_struct *qwork)
+{
+ struct vhost_dev *dev =
+ container_of(qwork, struct vhost_dev, qwork);
+ struct vhost_work *work = NULL;
+ unsigned uninitialized_var(seq);
+ struct mm_struct *prev_mm = NULL;
+ mm_segment_t oldfs = get_fs();
+
+ set_fs(USER_DS);
+
+ for (;;) {
+
+ spin_lock_irq(&dev->work_lock);
+
+ if (list_empty(&dev->work_list)) {
+ spin_unlock(&dev->work_lock);
+ break;
+ }
+
+ work = list_first_entry(&dev->work_list,
+ struct vhost_work, node);
+ list_del_init(&work->node);
+ seq = work->queue_seq;
+
+ if (prev_mm != dev->mm) {
+ if (prev_mm)
+ unuse_mm(prev_mm);
+ prev_mm = dev->mm;
+ use_mm(prev_mm);
+ }
+
+ spin_unlock_irq(&dev->work_lock);
+
+ if (work) {
+ work->fn(work);
+
+ spin_lock_irq(&dev->work_lock);
+ work->done_seq = seq;
+ if (work->flushing)
+ wake_up_all(&work->done);
+ spin_unlock_irq(&dev->work_lock);
+
+ }
+ }
+
+ if (prev_mm)
+ unuse_mm(prev_mm);
+ set_fs(oldfs);
+}
+
+int vhost_wq_init(void)
+{
+ qworker = alloc_workqueue("vhost_worker",
+ WQ_MEM_RECLAIM|WQ_CPU_INTENSIVE|WQ_SYSFS, 0);
+ if (!qworker)
+ return -ENOMEM;
+ return 0;
+}
+EXPORT_SYMBOL_GPL(vhost_wq_init);
+
+void vhost_wq_cleanup(void)
+{
+ destroy_workqueue(qworker);
+}
+EXPORT_SYMBOL_GPL(vhost_wq_cleanup);
+
static int __init vhost_init(void)
{
return 0;
diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h
index 4465ed5..3f6c147 100644
--- a/drivers/vhost/vhost.h
+++ b/drivers/vhost/vhost.h
@@ -125,6 +125,8 @@ struct vhost_dev {
spinlock_t work_lock;
struct list_head work_list;
struct task_struct *worker;
+ int use_wq;
+ struct work_struct qwork;
};
long vhost_dev_init(struct vhost_dev *, struct vhost_virtqueue **vqs, int nvqs);
@@ -161,6 +163,10 @@ bool vhost_enable_notify(struct vhost_dev *, struct vhost_virtqueue *);
int vhost_log_write(struct vhost_virtqueue *vq, struct vhost_log *log,
unsigned int log_num, u64 len);
+/* Experimental cmwq decls */
+int vhost_wq_init(void);
+void vhost_wq_cleanup(void);
+
#define vq_err(vq, fmt, ...) do { \
pr_debug(pr_fmt(fmt), ##__VA_ARGS__); \
if ((vq)->error_ctx) \
--
1.8.3.1
--
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