On Mon, Nov 14, 2022 at 3:16 PM Xie Yongji <xieyongji@xxxxxxxxxxxxx> wrote:
>
> Add sysfs interface for each vduse virtqueue to setup
> irq affinity. This would be useful for performance
> tuning, e.g., mitigate the virtqueue lock contention
> in virtio block driver.
Do we have any perforamnce numbers for this?
Btw, I wonder if irq is the best for the name since we actually don't
use IRQ at all. I guess using "callback" might be better?
Thanks
>
> Signed-off-by: Xie Yongji <xieyongji@xxxxxxxxxxxxx>
> ---
> drivers/vdpa/vdpa_user/vduse_dev.c | 113 ++++++++++++++++++++++++++---
> 1 file changed, 102 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/vdpa/vdpa_user/vduse_dev.c b/drivers/vdpa/vdpa_user/vduse_dev.c
> index 9303942c2e64..3a0922fa7eb2 100644
> --- a/drivers/vdpa/vdpa_user/vduse_dev.c
> +++ b/drivers/vdpa/vdpa_user/vduse_dev.c
> @@ -57,6 +57,7 @@ struct vduse_virtqueue {
> struct vdpa_callback cb;
> struct work_struct inject;
> struct work_struct kick;
> + struct kobject kobj;
> int irq_affinity;
> };
>
> @@ -1347,6 +1348,88 @@ static const struct file_operations vduse_dev_fops = {
> .llseek = noop_llseek,
> };
>
> +static ssize_t irq_affinity_show(struct vduse_virtqueue *vq, char *buf)
> +{
> + return sprintf(buf, "%d\n", vq->irq_affinity);
> +}
> +
> +static ssize_t irq_affinity_store(struct vduse_virtqueue *vq,
> + const char *buf, size_t count)
> +{
> + int val;
> +
> + if (kstrtoint(buf, 0, &val) < 0)
> + return -EINVAL;
> +
> + if (!(val == -1 || (val <= nr_cpu_ids && val >= 0 && cpu_online(val))))
> + return -EINVAL;
> +
> + vq->irq_affinity = val;
> +
> + return count;
> +}
> +
> +struct vq_sysfs_entry {
> + struct attribute attr;
> + ssize_t (*show)(struct vduse_virtqueue *vq, char *buf);
> + ssize_t (*store)(struct vduse_virtqueue *vq, const char *buf,
> + size_t count);
> +};
> +
> +static struct vq_sysfs_entry irq_affinity_attr = __ATTR_RW(irq_affinity);
> +
> +static struct attribute *vq_attrs[] = {
> + &irq_affinity_attr.attr,
> + NULL,
> +};
> +ATTRIBUTE_GROUPS(vq);
> +
> +static ssize_t vq_attr_show(struct kobject *kobj, struct attribute *attr,
> + char *buf)
> +{
> + struct vduse_virtqueue *vq = container_of(kobj,
> + struct vduse_virtqueue, kobj);
> + struct vq_sysfs_entry *entry = container_of(attr,
> + struct vq_sysfs_entry, attr);
> +
> + if (!entry->show)
> + return -EIO;
> +
> + return entry->show(vq, buf);
> +}
> +
> +static ssize_t vq_attr_store(struct kobject *kobj, struct attribute *attr,
> + const char *buf, size_t count)
> +{
> + struct vduse_virtqueue *vq = container_of(kobj,
> + struct vduse_virtqueue, kobj);
> + struct vq_sysfs_entry *entry = container_of(attr,
> + struct vq_sysfs_entry, attr);
> +
> + if (!entry->store)
> + return -EIO;
> +
> + return entry->store(vq, buf, count);
> +}
> +
> +static const struct sysfs_ops vq_sysfs_ops = {
> + .show = vq_attr_show,
> + .store = vq_attr_store,
> +};
> +
> +static void vq_release(struct kobject *kobj)
> +{
> + struct vduse_virtqueue *vq = container_of(kobj,
> + struct vduse_virtqueue, kobj);
> + kfree(vq);
> +}
> +
> +static struct kobj_type vq_type = {
> + .release = vq_release,
> + .sysfs_ops = &vq_sysfs_ops,
> + .default_groups = vq_groups,
> +};
> +
> static void vduse_dev_deinit_vqs(struct vduse_dev *dev)
> {
> int i;
> @@ -1355,13 +1438,13 @@ static void vduse_dev_deinit_vqs(struct vduse_dev *dev)
> return;
>
> for (i = 0; i < dev->vq_num; i++)
> - kfree(dev->vqs[i]);
> + kobject_put(&dev->vqs[i]->kobj);
> kfree(dev->vqs);
> }
>
> static int vduse_dev_init_vqs(struct vduse_dev *dev, u32 vq_align, u32 vq_num)
> {
> - int i;
> + int ret, i;
>
> dev->vq_align = vq_align;
> dev->vq_num = vq_num;
> @@ -1371,8 +1454,10 @@ static int vduse_dev_init_vqs(struct vduse_dev *dev, u32 vq_align, u32 vq_num)
>
> for (i = 0; i < vq_num; i++) {
> dev->vqs[i] = kzalloc(sizeof(*dev->vqs[i]), GFP_KERNEL);
> - if (!dev->vqs[i])
> + if (!dev->vqs[i]) {
> + ret = -ENOMEM;
> goto err;
> + }
>
> dev->vqs[i]->index = i;
> dev->vqs[i]->irq_affinity = -1;
> @@ -1380,15 +1465,20 @@ static int vduse_dev_init_vqs(struct vduse_dev *dev, u32 vq_align, u32 vq_num)
> INIT_WORK(&dev->vqs[i]->kick, vduse_vq_kick_work);
> spin_lock_init(&dev->vqs[i]->kick_lock);
> spin_lock_init(&dev->vqs[i]->irq_lock);
> + kobject_init(&dev->vqs[i]->kobj, &vq_type);
> + ret = kobject_add(&dev->vqs[i]->kobj,
> + &dev->dev->kobj, "vq%d", i);
> + if (ret)
> + goto err;
> }
>
> return 0;
> err:
> while (i--)
> - kfree(dev->vqs[i]);
> + kobject_put(&dev->vqs[i]->kobj);
> kfree(dev->vqs);
> dev->vqs = NULL;
> - return -ENOMEM;
> + return ret;
> }
>
> static struct vduse_dev *vduse_dev_create(void)
> @@ -1563,10 +1653,6 @@ static int vduse_create_dev(struct vduse_dev_config *config,
> dev->config = config_buf;
> dev->config_size = config->config_size;
>
> - ret = vduse_dev_init_vqs(dev, config->vq_align, config->vq_num);
> - if (ret)
> - goto err_vqs;
> -
> ret = idr_alloc(&vduse_idr, dev, 1, VDUSE_DEV_MAX, GFP_KERNEL);
> if (ret < 0)
> goto err_idr;
> @@ -1580,14 +1666,19 @@ static int vduse_create_dev(struct vduse_dev_config *config,
> ret = PTR_ERR(dev->dev);
> goto err_dev;
> }
> +
> + ret = vduse_dev_init_vqs(dev, config->vq_align, config->vq_num);
> + if (ret)
> + goto err_vqs;
> +
> __module_get(THIS_MODULE);
>
> return 0;
> +err_vqs:
> + device_destroy(vduse_class, MKDEV(MAJOR(vduse_major), dev->minor));
> err_dev:
> idr_remove(&vduse_idr, dev->minor);
> err_idr:
> - vduse_dev_deinit_vqs(dev);
> -err_vqs:
> vduse_domain_destroy(dev->domain);
> err_domain:
> kfree(dev->name);
> --
> 2.20.1
>
_______________________________________________
Virtualization mailing list
Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx
https://lists.linuxfoundation.org/mailman/listinfo/virtualization
