netdev - Re: [RFC v4 10/11] vduse: Introduce a workqueue for irq injection

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Date:   Thu, 4 Mar 2021 14:59:39 +0800
From:   Jason Wang <jasowang@...hat.com>
To:     Xie Yongji <xieyongji@...edance.com>, mst@...hat.com,
        stefanha@...hat.com, sgarzare@...hat.com, parav@...dia.com,
        bob.liu@...cle.com, hch@...radead.org, rdunlap@...radead.org,
        willy@...radead.org, viro@...iv.linux.org.uk, axboe@...nel.dk,
        bcrl@...ck.org, corbet@....net
Cc:     virtualization@...ts.linux-foundation.org, netdev@...r.kernel.org,
        kvm@...r.kernel.org, linux-aio@...ck.org,
        linux-fsdevel@...r.kernel.org
Subject: Re: [RFC v4 10/11] vduse: Introduce a workqueue for irq injection


On 2021/2/23 7:50 下午, Xie Yongji wrote:
> This patch introduces a workqueue to support injecting
> virtqueue's interrupt asynchronously. This is mainly
> for performance considerations which makes sure the push()
> and pop() for used vring can be asynchronous.


Do you have pref numbers for this patch?

Thanks


>
> Signed-off-by: Xie Yongji <xieyongji@...edance.com>
> ---
>   drivers/vdpa/vdpa_user/vduse_dev.c | 29 +++++++++++++++++++++++------
>   1 file changed, 23 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/vdpa/vdpa_user/vduse_dev.c b/drivers/vdpa/vdpa_user/vduse_dev.c
> index 8042d3fa57f1..f5adeb9ee027 100644
> --- a/drivers/vdpa/vdpa_user/vduse_dev.c
> +++ b/drivers/vdpa/vdpa_user/vduse_dev.c
> @@ -42,6 +42,7 @@ struct vduse_virtqueue {
>   	spinlock_t irq_lock;
>   	struct eventfd_ctx *kickfd;
>   	struct vdpa_callback cb;
> +	struct work_struct inject;
>   };
>   
>   struct vduse_dev;
> @@ -99,6 +100,7 @@ static DEFINE_IDA(vduse_ida);
>   
>   static dev_t vduse_major;
>   static struct class *vduse_class;
> +static struct workqueue_struct *vduse_irq_wq;
>   
>   static inline struct vduse_dev *vdpa_to_vduse(struct vdpa_device *vdpa)
>   {
> @@ -852,6 +854,17 @@ static int vduse_kickfd_setup(struct vduse_dev *dev,
>   	return 0;
>   }
>   
> +static void vduse_vq_irq_inject(struct work_struct *work)
> +{
> +	struct vduse_virtqueue *vq = container_of(work,
> +					struct vduse_virtqueue, inject);
> +
> +	spin_lock_irq(&vq->irq_lock);
> +	if (vq->ready && vq->cb.callback)
> +		vq->cb.callback(vq->cb.private);
> +	spin_unlock_irq(&vq->irq_lock);
> +}
> +
>   static long vduse_dev_ioctl(struct file *file, unsigned int cmd,
>   			unsigned long arg)
>   {
> @@ -917,12 +930,7 @@ static long vduse_dev_ioctl(struct file *file, unsigned int cmd,
>   			break;
>   
>   		vq = &dev->vqs[arg];
> -		spin_lock_irq(&vq->irq_lock);
> -		if (vq->ready && vq->cb.callback) {
> -			vq->cb.callback(vq->cb.private);
> -			ret = 0;
> -		}
> -		spin_unlock_irq(&vq->irq_lock);
> +		queue_work(vduse_irq_wq, &vq->inject);
>   		break;
>   	}
>   	case VDUSE_INJECT_CONFIG_IRQ:
> @@ -1109,6 +1117,7 @@ static int vduse_create_dev(struct vduse_dev_config *config)
>   
>   	for (i = 0; i < dev->vq_num; i++) {
>   		dev->vqs[i].index = i;
> +		INIT_WORK(&dev->vqs[i].inject, vduse_vq_irq_inject);
>   		spin_lock_init(&dev->vqs[i].kick_lock);
>   		spin_lock_init(&dev->vqs[i].irq_lock);
>   	}
> @@ -1333,6 +1342,11 @@ static int vduse_init(void)
>   	if (ret)
>   		goto err_chardev;
>   
> +	vduse_irq_wq = alloc_workqueue("vduse-irq",
> +				WQ_HIGHPRI | WQ_SYSFS | WQ_UNBOUND, 0);
> +	if (!vduse_irq_wq)
> +		goto err_wq;
> +
>   	ret = vduse_domain_init();
>   	if (ret)
>   		goto err_domain;
> @@ -1344,6 +1358,8 @@ static int vduse_init(void)
>   	return 0;
>   err_mgmtdev:
>   	vduse_domain_exit();
> +err_wq:
> +	destroy_workqueue(vduse_irq_wq);
>   err_domain:
>   	unregister_chrdev_region(vduse_major, VDUSE_DEV_MAX);
>   err_chardev:
> @@ -1359,6 +1375,7 @@ static void vduse_exit(void)
>   	misc_deregister(&vduse_misc);
>   	class_destroy(vduse_class);
>   	unregister_chrdev_region(vduse_major, VDUSE_DEV_MAX);
> +	destroy_workqueue(vduse_irq_wq);
>   	vduse_domain_exit();
>   	vduse_mgmtdev_exit();
>   }