Virtualization - Oct 2021 - [PATCH v2 1/3] virtio: cache indirect desc for split

In the case of using indirect, indirect desc must be allocated and
released each time, which increases a lot of cpu overhead.

Here, a cache is added for indirect. If the number of indirect desc to be
applied for is less than VIRT_QUEUE_CACHE_DESC_NUM, the desc array with
the size of VIRT_QUEUE_CACHE_DESC_NUM is fixed and cached for reuse.

Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com>
---
 drivers/virtio/virtio.c      |  6 +++
 drivers/virtio/virtio_ring.c | 77 ++++++++++++++++++++++++++++++++----
 include/linux/virtio.h       | 14 +++++++
 3 files changed, 89 insertions(+), 8 deletions(-)

diff --git a/drivers/virtio/virtio.c b/drivers/virtio/virtio.c
index 0a5b54034d4b..1047149ac2a4 100644
--- a/drivers/virtio/virtio.c
+++ b/drivers/virtio/virtio.c
@@ -431,6 +431,12 @@ bool is_virtio_device(struct device *dev)
 }
 EXPORT_SYMBOL_GPL(is_virtio_device);
 
+void virtio_set_desc_cache(struct virtio_device *dev, u32 thr)
+{
+	dev->desc_cache_thr = thr;
+}
+EXPORT_SYMBOL_GPL(virtio_set_desc_cache);
+
 void unregister_virtio_device(struct virtio_device *dev)
 {
 	int index = dev->index; /* save for after device release */
diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index dd95dfd85e98..0ebcd4f12d3b 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -117,6 +117,15 @@ struct vring_virtqueue {
 	/* Hint for event idx: already triggered no need to disable. */
 	bool event_triggered;
 
+	/* desc cache threshold
+	 *    0   - disable desc cache
+	 *    > 0 - enable desc cache. As the threshold of the desc cache.
+	 */
+	u32 desc_cache_thr;
+
+	/* desc cache chain */
+	struct list_head desc_cache;
+
 	union {
 		/* Available for split ring */
 		struct {
@@ -423,7 +432,53 @@ static unsigned int vring_unmap_one_split(const struct
vring_virtqueue *vq,
 	return extra[i].next;
 }
 
-static struct vring_desc *alloc_indirect_split(struct virtqueue *_vq,
+static void desc_cache_free(struct list_head *head)
+{
+	struct list_head *n, *pos;
+
+	BUILD_BUG_ON(sizeof(struct list_head) > sizeof(struct vring_desc));
+	BUILD_BUG_ON(sizeof(struct list_head) > sizeof(struct vring_packed_desc));
+
+	list_for_each_prev_safe(pos, n, head)
+		kfree(pos);
+}
+
+static void __desc_cache_put(struct vring_virtqueue *vq,
+			     struct list_head *node, int n)
+{
+	if (n <= vq->desc_cache_thr)
+		list_add(node, &vq->desc_cache);
+	else
+		kfree(node);
+}
+
+#define desc_cache_put(vq, desc, n) \
+	__desc_cache_put(vq, (struct list_head *)desc, n)
+
+static void *desc_cache_get(struct vring_virtqueue *vq,
+			    int size, int n, gfp_t gfp)
+{
+	struct list_head *node;
+
+	if (n > vq->desc_cache_thr)
+		return kmalloc_array(n, size, gfp);
+
+	if (!list_empty(&vq->desc_cache)) {
+		node = vq->desc_cache.next;
+		list_del(node);
+		return node;
+	}
+
+	return kmalloc_array(vq->desc_cache_thr, size, gfp);
+}
+
+#define _desc_cache_get(vq, n, gfp, tp) \
+	((tp *)desc_cache_get(vq, (sizeof(tp)), n, gfp))
+
+#define desc_cache_get_split(vq, n, gfp) \
+	_desc_cache_get(vq, n, gfp, struct vring_desc)
+
+static struct vring_desc *alloc_indirect_split(struct vring_virtqueue *vq,
 					       unsigned int total_sg,
 					       gfp_t gfp)
 {
@@ -437,12 +492,12 @@ static struct vring_desc *alloc_indirect_split(struct
virtqueue *_vq,
 	 */
 	gfp &= ~__GFP_HIGHMEM;
 
-	desc = kmalloc_array(total_sg, sizeof(struct vring_desc), gfp);
+	desc = desc_cache_get_split(vq, total_sg, gfp);
 	if (!desc)
 		return NULL;
 
 	for (i = 0; i < total_sg; i++)
-		desc[i].next = cpu_to_virtio16(_vq->vdev, i + 1);
+		desc[i].next = cpu_to_virtio16(vq->vq.vdev, i + 1);
 	return desc;
 }
 
@@ -508,7 +563,7 @@ static inline int virtqueue_add_split(struct virtqueue *_vq,
 	head = vq->free_head;
 
 	if (virtqueue_use_indirect(_vq, total_sg))
-		desc = alloc_indirect_split(_vq, total_sg, gfp);
+		desc = alloc_indirect_split(vq, total_sg, gfp);
 	else {
 		desc = NULL;
 		WARN_ON_ONCE(total_sg > vq->split.vring.num &&
!vq->indirect);
@@ -652,7 +707,7 @@ static inline int virtqueue_add_split(struct virtqueue *_vq,
 	}
 
 	if (indirect)
-		kfree(desc);
+		desc_cache_put(vq, desc, total_sg);
 
 	END_USE(vq);
 	return -ENOMEM;
@@ -717,7 +772,7 @@ static void detach_buf_split(struct vring_virtqueue *vq,
unsigned int head,
 	if (vq->indirect) {
 		struct vring_desc *indir_desc  				vq->split.desc_state[head].indir_desc;
-		u32 len;
+		u32 len, n;
 
 		/* Free the indirect table, if any, now that it's unmapped. */
 		if (!indir_desc)
@@ -729,10 +784,12 @@ static void detach_buf_split(struct vring_virtqueue *vq,
unsigned int head,
 				VRING_DESC_F_INDIRECT));
 		BUG_ON(len == 0 || len % sizeof(struct vring_desc));
 
-		for (j = 0; j < len / sizeof(struct vring_desc); j++)
+		n = len / sizeof(struct vring_desc);
+
+		for (j = 0; j < n; j++)
 			vring_unmap_one_split_indirect(vq, &indir_desc[j]);
 
-		kfree(indir_desc);
+		desc_cache_put(vq, indir_desc, n);
 		vq->split.desc_state[head].indir_desc = NULL;
 	} else if (ctx) {
 		*ctx = vq->split.desc_state[head].indir_desc;
@@ -2199,6 +2256,9 @@ struct virtqueue *__vring_new_virtqueue(unsigned int
index,
 	vq->indirect = virtio_has_feature(vdev, VIRTIO_RING_F_INDIRECT_DESC)
&&
 		!context;
 	vq->event = virtio_has_feature(vdev, VIRTIO_RING_F_EVENT_IDX);
+	vq->desc_cache_thr = vdev->desc_cache_thr;
+
+	INIT_LIST_HEAD(&vq->desc_cache);
 
 	if (virtio_has_feature(vdev, VIRTIO_F_ORDER_PLATFORM))
 		vq->weak_barriers = false;
@@ -2329,6 +2389,7 @@ void vring_del_virtqueue(struct virtqueue *_vq)
 	if (!vq->packed_ring) {
 		kfree(vq->split.desc_state);
 		kfree(vq->split.desc_extra);
+		desc_cache_free(&vq->desc_cache);
 	}
 	kfree(vq);
 }
diff --git a/include/linux/virtio.h b/include/linux/virtio.h
index 41edbc01ffa4..bda6f9853e97 100644
--- a/include/linux/virtio.h
+++ b/include/linux/virtio.h
@@ -118,6 +118,7 @@ struct virtio_device {
 	struct list_head vqs;
 	u64 features;
 	void *priv;
+	u32 desc_cache_thr;
 };
 
 static inline struct virtio_device *dev_to_virtio(struct device *_dev)
@@ -130,6 +131,19 @@ int register_virtio_device(struct virtio_device *dev);
 void unregister_virtio_device(struct virtio_device *dev);
 bool is_virtio_device(struct device *dev);
 
+/**
+ * virtio_set_desc_cache - set virtio ring desc cache threshold
+ *
+ * virtio will cache the allocated indirect desc.
+ *
+ * This function must be called before find_vqs.
+ *
+ * @thr:
+ *    0   - disable desc cache
+ *    > 0 - enable desc cache. As the threshold of the desc cache.
+ */
+void virtio_set_desc_cache(struct virtio_device *dev, u32 thr);
+
 void virtio_break_device(struct virtio_device *dev);
 
 void virtio_config_changed(struct virtio_device *dev);
-- 
2.31.0

On Thu, Oct 28, 2021 at 6:49 PM Xuan Zhuo <xuanzhuo at linux.alibaba.com>
wrote:
>
> In the case of using indirect, indirect desc must be allocated and
> released each time, which increases a lot of cpu overhead.
>
> Here, a cache is added for indirect. If the number of indirect desc to be
> applied for is less than VIRT_QUEUE_CACHE_DESC_NUM, the desc array with
> the size of VIRT_QUEUE_CACHE_DESC_NUM is fixed and cached for reuse.
The commit log looks out of date? It's actually desc_cache_thr now.
>
> Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com>
> ---
>  drivers/virtio/virtio.c      |  6 +++
>  drivers/virtio/virtio_ring.c | 77 ++++++++++++++++++++++++++++++++----
>  include/linux/virtio.h       | 14 +++++++
>  3 files changed, 89 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/virtio/virtio.c b/drivers/virtio/virtio.c
> index 0a5b54034d4b..1047149ac2a4 100644
> --- a/drivers/virtio/virtio.c
> +++ b/drivers/virtio/virtio.c
> @@ -431,6 +431,12 @@ bool is_virtio_device(struct device *dev)
>  }
>  EXPORT_SYMBOL_GPL(is_virtio_device);
>
> +void virtio_set_desc_cache(struct virtio_device *dev, u32 thr)
> +{
> +       dev->desc_cache_thr = thr;
> +}
> +EXPORT_SYMBOL_GPL(virtio_set_desc_cache);
> +
>  void unregister_virtio_device(struct virtio_device *dev)
>  {
>         int index = dev->index; /* save for after device release */
> diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
> index dd95dfd85e98..0ebcd4f12d3b 100644
> --- a/drivers/virtio/virtio_ring.c
> +++ b/drivers/virtio/virtio_ring.c
> @@ -117,6 +117,15 @@ struct vring_virtqueue {
>         /* Hint for event idx: already triggered no need to disable. */
>         bool event_triggered;
>
> +       /* desc cache threshold
> +        *    0   - disable desc cache
> +        *    > 0 - enable desc cache. As the threshold of the desc
cache.
> +        */
> +       u32 desc_cache_thr;
> +
> +       /* desc cache chain */
> +       struct list_head desc_cache;
> +
>         union {
>                 /* Available for split ring */
>                 struct {
> @@ -423,7 +432,53 @@ static unsigned int vring_unmap_one_split(const struct
vring_virtqueue *vq,
>         return extra[i].next;
>  }
>
> -static struct vring_desc *alloc_indirect_split(struct virtqueue *_vq,
> +static void desc_cache_free(struct list_head *head)
> +{
> +       struct list_head *n, *pos;
> +
> +       BUILD_BUG_ON(sizeof(struct list_head) > sizeof(struct
vring_desc));
> +       BUILD_BUG_ON(sizeof(struct list_head) > sizeof(struct
vring_packed_desc));
> +
> +       list_for_each_prev_safe(pos, n, head)
> +               kfree(pos);
> +}
> +
> +static void __desc_cache_put(struct vring_virtqueue *vq,
> +                            struct list_head *node, int n)
> +{
> +       if (n <= vq->desc_cache_thr)
> +               list_add(node, &vq->desc_cache);
> +       else
> +               kfree(node);
> +}
> +
> +#define desc_cache_put(vq, desc, n) \
> +       __desc_cache_put(vq, (struct list_head *)desc, n)
> +
> +static void *desc_cache_get(struct vring_virtqueue *vq,
> +                           int size, int n, gfp_t gfp)
> +{
> +       struct list_head *node;
> +
> +       if (n > vq->desc_cache_thr)
> +               return kmalloc_array(n, size, gfp);
> +
> +       if (!list_empty(&vq->desc_cache)) {
> +               node = vq->desc_cache.next;
> +               list_del(node);
> +               return node;
> +       }
> +
> +       return kmalloc_array(vq->desc_cache_thr, size, gfp);
Instead of doing the if .. kmalloc_array here. I wonder if we can
simply pre-allocate per buffer indirect descriptors array.

E.g if we use MAX_SKB_FRAGS + 1, it will be ~64KB for 256 queue size
and ~272KB for 1024 queue size.

Then we avoid list manipulation and kmalloc in datapath with much more
simpler codes.

Thanks
> +}
> +
> +#define _desc_cache_get(vq, n, gfp, tp) \
> +       ((tp *)desc_cache_get(vq, (sizeof(tp)), n, gfp))
> +
> +#define desc_cache_get_split(vq, n, gfp) \
> +       _desc_cache_get(vq, n, gfp, struct vring_desc)
> +
> +static struct vring_desc *alloc_indirect_split(struct vring_virtqueue *vq,
>                                                unsigned int total_sg,
>                                                gfp_t gfp)
>  {
> @@ -437,12 +492,12 @@ static struct vring_desc *alloc_indirect_split(struct
virtqueue *_vq,
>          */
>         gfp &= ~__GFP_HIGHMEM;
>
> -       desc = kmalloc_array(total_sg, sizeof(struct vring_desc), gfp);
> +       desc = desc_cache_get_split(vq, total_sg, gfp);
>         if (!desc)
>                 return NULL;
>
>         for (i = 0; i < total_sg; i++)
> -               desc[i].next = cpu_to_virtio16(_vq->vdev, i + 1);
> +               desc[i].next = cpu_to_virtio16(vq->vq.vdev, i + 1);
>         return desc;
>  }
>
> @@ -508,7 +563,7 @@ static inline int virtqueue_add_split(struct virtqueue
*_vq,
>         head = vq->free_head;
>
>         if (virtqueue_use_indirect(_vq, total_sg))
> -               desc = alloc_indirect_split(_vq, total_sg, gfp);
> +               desc = alloc_indirect_split(vq, total_sg, gfp);
>         else {
>                 desc = NULL;
>                 WARN_ON_ONCE(total_sg > vq->split.vring.num
&& !vq->indirect);
> @@ -652,7 +707,7 @@ static inline int virtqueue_add_split(struct virtqueue
*_vq,
>         }
>
>         if (indirect)
> -               kfree(desc);
> +               desc_cache_put(vq, desc, total_sg);
>
>         END_USE(vq);
>         return -ENOMEM;
> @@ -717,7 +772,7 @@ static void detach_buf_split(struct vring_virtqueue
*vq, unsigned int head,
>         if (vq->indirect) {
>                 struct vring_desc *indir_desc >                         
vq->split.desc_state[head].indir_desc;
> -               u32 len;
> +               u32 len, n;
>
>                 /* Free the indirect table, if any, now that it's
unmapped. */
>                 if (!indir_desc)
> @@ -729,10 +784,12 @@ static void detach_buf_split(struct vring_virtqueue
*vq, unsigned int head,
>                                 VRING_DESC_F_INDIRECT));
>                 BUG_ON(len == 0 || len % sizeof(struct vring_desc));
>
> -               for (j = 0; j < len / sizeof(struct vring_desc); j++)
> +               n = len / sizeof(struct vring_desc);
> +
> +               for (j = 0; j < n; j++)
>                         vring_unmap_one_split_indirect(vq,
&indir_desc[j]);
>
> -               kfree(indir_desc);
> +               desc_cache_put(vq, indir_desc, n);
>                 vq->split.desc_state[head].indir_desc = NULL;
>         } else if (ctx) {
>                 *ctx = vq->split.desc_state[head].indir_desc;
> @@ -2199,6 +2256,9 @@ struct virtqueue *__vring_new_virtqueue(unsigned int
index,
>         vq->indirect = virtio_has_feature(vdev,
VIRTIO_RING_F_INDIRECT_DESC) &&
>                 !context;
>         vq->event = virtio_has_feature(vdev, VIRTIO_RING_F_EVENT_IDX);
> +       vq->desc_cache_thr = vdev->desc_cache_thr;
> +
> +       INIT_LIST_HEAD(&vq->desc_cache);
>
>         if (virtio_has_feature(vdev, VIRTIO_F_ORDER_PLATFORM))
>                 vq->weak_barriers = false;
> @@ -2329,6 +2389,7 @@ void vring_del_virtqueue(struct virtqueue *_vq)
>         if (!vq->packed_ring) {
>                 kfree(vq->split.desc_state);
>                 kfree(vq->split.desc_extra);
> +               desc_cache_free(&vq->desc_cache);
>         }
>         kfree(vq);
>  }
> diff --git a/include/linux/virtio.h b/include/linux/virtio.h
> index 41edbc01ffa4..bda6f9853e97 100644
> --- a/include/linux/virtio.h
> +++ b/include/linux/virtio.h
> @@ -118,6 +118,7 @@ struct virtio_device {
>         struct list_head vqs;
>         u64 features;
>         void *priv;
> +       u32 desc_cache_thr;
>  };
>
>  static inline struct virtio_device *dev_to_virtio(struct device *_dev)
> @@ -130,6 +131,19 @@ int register_virtio_device(struct virtio_device *dev);
>  void unregister_virtio_device(struct virtio_device *dev);
>  bool is_virtio_device(struct device *dev);
>
> +/**
> + * virtio_set_desc_cache - set virtio ring desc cache threshold
> + *
> + * virtio will cache the allocated indirect desc.
> + *
> + * This function must be called before find_vqs.
> + *
> + * @thr:
> + *    0   - disable desc cache
> + *    > 0 - enable desc cache. As the threshold of the desc cache.
> + */
> +void virtio_set_desc_cache(struct virtio_device *dev, u32 thr);
> +
>  void virtio_break_device(struct virtio_device *dev);
>
>  void virtio_config_changed(struct virtio_device *dev);
> --
> 2.31.0
>

On Thu, Oct 28, 2021 at 06:49:17PM +0800, Xuan Zhuo
wrote:
> In the case of using indirect, indirect desc must be allocated and
> released each time, which increases a lot of cpu overhead.
> 
> Here, a cache is added for indirect. If the number of indirect desc to be
> applied for is less than VIRT_QUEUE_CACHE_DESC_NUM, the desc array with
> the size of VIRT_QUEUE_CACHE_DESC_NUM is fixed and cached for reuse.
> 
> Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com>
What bothers me here is what happens if cache gets
filled on one numa node, then used on another?

> ---
>  drivers/virtio/virtio.c      |  6 +++
>  drivers/virtio/virtio_ring.c | 77 ++++++++++++++++++++++++++++++++----
>  include/linux/virtio.h       | 14 +++++++
>  3 files changed, 89 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/virtio/virtio.c b/drivers/virtio/virtio.c
> index 0a5b54034d4b..1047149ac2a4 100644
> --- a/drivers/virtio/virtio.c
> +++ b/drivers/virtio/virtio.c
> @@ -431,6 +431,12 @@ bool is_virtio_device(struct device *dev)
>  }
>  EXPORT_SYMBOL_GPL(is_virtio_device);
>  
> +void virtio_set_desc_cache(struct virtio_device *dev, u32 thr)
> +{
> +	dev->desc_cache_thr = thr;
> +}
> +EXPORT_SYMBOL_GPL(virtio_set_desc_cache);
> +
>  void unregister_virtio_device(struct virtio_device *dev)
>  {
>  	int index = dev->index; /* save for after device release */
> diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
> index dd95dfd85e98..0ebcd4f12d3b 100644
> --- a/drivers/virtio/virtio_ring.c
> +++ b/drivers/virtio/virtio_ring.c
> @@ -117,6 +117,15 @@ struct vring_virtqueue {
>  	/* Hint for event idx: already triggered no need to disable. */
>  	bool event_triggered;
>  
> +	/* desc cache threshold
> +	 *    0   - disable desc cache
> +	 *    > 0 - enable desc cache. As the threshold of the desc cache.
> +	 */
> +	u32 desc_cache_thr;
not really descriptive. also pls eschew abbreviation.
> +
> +	/* desc cache chain */
> +	struct list_head desc_cache;
hmm this puts extra pressure on cache. you never need to drop
things in the middle. llist_head would be better I
think ... no?

> +
>  	union {
>  		/* Available for split ring */
>  		struct {
> @@ -423,7 +432,53 @@ static unsigned int vring_unmap_one_split(const struct
vring_virtqueue *vq,
>  	return extra[i].next;
>  }
>  
> -static struct vring_desc *alloc_indirect_split(struct virtqueue *_vq,
> +static void desc_cache_free(struct list_head *head)
> +{
> +	struct list_head *n, *pos;
> +
> +	BUILD_BUG_ON(sizeof(struct list_head) > sizeof(struct vring_desc));
> +	BUILD_BUG_ON(sizeof(struct list_head) > sizeof(struct
vring_packed_desc));
> +
> +	list_for_each_prev_safe(pos, n, head)
> +		kfree(pos);
> +}
> +
> +static void __desc_cache_put(struct vring_virtqueue *vq,
> +			     struct list_head *node, int n)
> +{
> +	if (n <= vq->desc_cache_thr)
> +		list_add(node, &vq->desc_cache);
> +	else
> +		kfree(node);
this bothers me. Do we really need a full VQ's worth of
indirect descriptors? Can't we set a limit on how many
are used?

> +}
> +
> +#define desc_cache_put(vq, desc, n) \
> +	__desc_cache_put(vq, (struct list_head *)desc, n)
replace with an inline function pls. in fact we dont need
__desc_cache_put at all.

> +
> +static void *desc_cache_get(struct vring_virtqueue *vq,
> +			    int size, int n, gfp_t gfp)
> +{
> +	struct list_head *node;
> +
> +	if (n > vq->desc_cache_thr)
> +		return kmalloc_array(n, size, gfp);
> +
> +	if (!list_empty(&vq->desc_cache)) {
> +		node = vq->desc_cache.next;
> +		list_del(node);
> +		return node;
> +	}
> +
> +	return kmalloc_array(vq->desc_cache_thr, size, gfp);
> +}
> +
> +#define _desc_cache_get(vq, n, gfp, tp) \
> +	((tp *)desc_cache_get(vq, (sizeof(tp)), n, gfp))
> +
> +#define desc_cache_get_split(vq, n, gfp) \
> +	_desc_cache_get(vq, n, gfp, struct vring_desc)
> +
same thing here.
> +static struct vring_desc *alloc_indirect_split(struct vring_virtqueue *vq,
>  					       unsigned int total_sg,
>  					       gfp_t gfp)
>  {
> @@ -437,12 +492,12 @@ static struct vring_desc *alloc_indirect_split(struct
virtqueue *_vq,
>  	 */
>  	gfp &= ~__GFP_HIGHMEM;
>  
> -	desc = kmalloc_array(total_sg, sizeof(struct vring_desc), gfp);
> +	desc = desc_cache_get_split(vq, total_sg, gfp);
>  	if (!desc)
>  		return NULL;
>  
>  	for (i = 0; i < total_sg; i++)
> -		desc[i].next = cpu_to_virtio16(_vq->vdev, i + 1);
> +		desc[i].next = cpu_to_virtio16(vq->vq.vdev, i + 1);
>  	return desc;
>  }
>  
> @@ -508,7 +563,7 @@ static inline int virtqueue_add_split(struct virtqueue
*_vq,
>  	head = vq->free_head;
>  
>  	if (virtqueue_use_indirect(_vq, total_sg))
> -		desc = alloc_indirect_split(_vq, total_sg, gfp);
> +		desc = alloc_indirect_split(vq, total_sg, gfp);
>  	else {
>  		desc = NULL;
>  		WARN_ON_ONCE(total_sg > vq->split.vring.num &&
!vq->indirect);
> @@ -652,7 +707,7 @@ static inline int virtqueue_add_split(struct virtqueue
*_vq,
>  	}
>  
>  	if (indirect)
> -		kfree(desc);
> +		desc_cache_put(vq, desc, total_sg);
>  
>  	END_USE(vq);
>  	return -ENOMEM;
> @@ -717,7 +772,7 @@ static void detach_buf_split(struct vring_virtqueue
*vq, unsigned int head,
>  	if (vq->indirect) {
>  		struct vring_desc *indir_desc >  			
vq->split.desc_state[head].indir_desc;
> -		u32 len;
> +		u32 len, n;
>  
>  		/* Free the indirect table, if any, now that it's unmapped. */
>  		if (!indir_desc)
> @@ -729,10 +784,12 @@ static void detach_buf_split(struct vring_virtqueue
*vq, unsigned int head,
>  				VRING_DESC_F_INDIRECT));
>  		BUG_ON(len == 0 || len % sizeof(struct vring_desc));
>  
> -		for (j = 0; j < len / sizeof(struct vring_desc); j++)
> +		n = len / sizeof(struct vring_desc);
> +
> +		for (j = 0; j < n; j++)
>  			vring_unmap_one_split_indirect(vq, &indir_desc[j]);
>  
> -		kfree(indir_desc);
> +		desc_cache_put(vq, indir_desc, n);
>  		vq->split.desc_state[head].indir_desc = NULL;
>  	} else if (ctx) {
>  		*ctx = vq->split.desc_state[head].indir_desc;
> @@ -2199,6 +2256,9 @@ struct virtqueue *__vring_new_virtqueue(unsigned int
index,
>  	vq->indirect = virtio_has_feature(vdev, VIRTIO_RING_F_INDIRECT_DESC)
&&
>  		!context;
>  	vq->event = virtio_has_feature(vdev, VIRTIO_RING_F_EVENT_IDX);
> +	vq->desc_cache_thr = vdev->desc_cache_thr;
> +
> +	INIT_LIST_HEAD(&vq->desc_cache);
>  
>  	if (virtio_has_feature(vdev, VIRTIO_F_ORDER_PLATFORM))
>  		vq->weak_barriers = false;
So e.g. for rx, we are wasting memory since indirect isn't used.

> @@ -2329,6 +2389,7 @@ void vring_del_virtqueue(struct virtqueue *_vq)
>  	if (!vq->packed_ring) {
>  		kfree(vq->split.desc_state);
>  		kfree(vq->split.desc_extra);
> +		desc_cache_free(&vq->desc_cache);
>  	}
>  	kfree(vq);
>  }
> diff --git a/include/linux/virtio.h b/include/linux/virtio.h
> index 41edbc01ffa4..bda6f9853e97 100644
> --- a/include/linux/virtio.h
> +++ b/include/linux/virtio.h
> @@ -118,6 +118,7 @@ struct virtio_device {
>  	struct list_head vqs;
>  	u64 features;
>  	void *priv;
> +	u32 desc_cache_thr;
>  };
>  
>  static inline struct virtio_device *dev_to_virtio(struct device *_dev)
> @@ -130,6 +131,19 @@ int register_virtio_device(struct virtio_device *dev);
>  void unregister_virtio_device(struct virtio_device *dev);
>  bool is_virtio_device(struct device *dev);
>  
> +/**
> + * virtio_set_desc_cache - set virtio ring desc cache threshold
> + *
> + * virtio will cache the allocated indirect desc.
> + *
> + * This function must be called before find_vqs.
> + *
> + * @thr:
> + *    0   - disable desc cache
> + *    > 0 - enable desc cache. As the threshold of the desc cache.
> + */
> +void virtio_set_desc_cache(struct virtio_device *dev, u32 thr);
> +
>  void virtio_break_device(struct virtio_device *dev);
>  
>  void virtio_config_changed(struct virtio_device *dev);
> -- 
> 2.31.0

On Sun, 31 Oct 2021 10:46:12 -0400, Michael S. Tsirkin <mst at redhat.com>
wrote:
> On Thu, Oct 28, 2021 at 06:49:17PM +0800, Xuan Zhuo wrote:
> > In the case of using indirect, indirect desc must be allocated and
> > released each time, which increases a lot of cpu overhead.
> >
> > Here, a cache is added for indirect. If the number of indirect desc to
be
> > applied for is less than VIRT_QUEUE_CACHE_DESC_NUM, the desc array
with
> > the size of VIRT_QUEUE_CACHE_DESC_NUM is fixed and cached for reuse.
> >
> > Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com>
>
> What bothers me here is what happens if cache gets
> filled on one numa node, then used on another?
Well, this is a good question, I didn't think about it before.

In this way, I feel that using kmem_cache_alloc's series of functions is a
good
solution. But when I tested it before, there was no improvement. I want to study
the reasons for this, and hope to solve this problem.

In addition, regarding the use of the kmem_cache_alloc_bulk function you
mentioned, I will also try to see it.
> > diff --git a/drivers/virtio/virtio_ring.c
b/drivers/virtio/virtio_ring.c
> > index dd95dfd85e98..0ebcd4f12d3b 100644
> > --- a/drivers/virtio/virtio_ring.c
> > +++ b/drivers/virtio/virtio_ring.c
> > @@ -117,6 +117,15 @@ struct vring_virtqueue {
> >  	/* Hint for event idx: already triggered no need to disable. */
> >  	bool event_triggered;
> >
> > +	/* desc cache threshold
> > +	 *    0   - disable desc cache
> > +	 *    > 0 - enable desc cache. As the threshold of the desc
cache.
> > +	 */
> > +	u32 desc_cache_thr;
>
> not really descriptive. also pls eschew abbreviation.
>
> > +
> > +	/* desc cache chain */
> > +	struct list_head desc_cache;
>
> hmm this puts extra pressure on cache. you never need to drop
> things in the middle. llist_head would be better I
> think ... no?

I tried to use llist_head before, but I found that it is a less-locked
implementation with some atomic operations. Since the cache here is exclusive to
vq, I feel that there is no need to use atomic operations. I replaced it with
list_head.

I don't know what you mean by "things in the middel".

>
>
> > +
> >  	union {
> >  		/* Available for split ring */
> >  		struct {
> > @@ -423,7 +432,53 @@ static unsigned int vring_unmap_one_split(const
struct vring_virtqueue *vq,
> >  	return extra[i].next;
> >  }
> >
> > -static struct vring_desc *alloc_indirect_split(struct virtqueue *_vq,
> > +static void desc_cache_free(struct list_head *head)
> > +{
> > +	struct list_head *n, *pos;
> > +
> > +	BUILD_BUG_ON(sizeof(struct list_head) > sizeof(struct
vring_desc));
> > +	BUILD_BUG_ON(sizeof(struct list_head) > sizeof(struct
vring_packed_desc));
> > +
> > +	list_for_each_prev_safe(pos, n, head)
> > +		kfree(pos);
> > +}
> > +
> > +static void __desc_cache_put(struct vring_virtqueue *vq,
> > +			     struct list_head *node, int n)
> > +{
> > +	if (n <= vq->desc_cache_thr)
> > +		list_add(node, &vq->desc_cache);
> > +	else
> > +		kfree(node);
>
> this bothers me. Do we really need a full VQ's worth of
> indirect descriptors? Can't we set a limit on how many
> are used?
>
I think, I don't quite understand what you mean, I guess you mean, do
multiple
vqs share a cache?

Then do we limit the total size of the shared space?

When the user calls virtqueue_add, if the number of sg used is greater than 1,
indirect desc will be used. If the number of sg is less than or equal to
desc_cache_thr, cache is used. When it is greater than
desc_cache_thr, kmalloc/kfree is used directly.

Because each item in the cache is a fixed number(desc_cache_thr) desc.


>
> > +}
> > +
> > +#define desc_cache_put(vq, desc, n) \
> > +	__desc_cache_put(vq, (struct list_head *)desc, n)
>
> replace with an inline function pls. in fact we dont need
> __desc_cache_put at all.
>
>
> > +
> > +static void *desc_cache_get(struct vring_virtqueue *vq,
> > +			    int size, int n, gfp_t gfp)
> > +{
> > +	struct list_head *node;
> > +
> > +	if (n > vq->desc_cache_thr)
> > +		return kmalloc_array(n, size, gfp);
> > +
> > +	if (!list_empty(&vq->desc_cache)) {
> > +		node = vq->desc_cache.next;
> > +		list_del(node);
> > +		return node;
> > +	}
> > +
> > +	return kmalloc_array(vq->desc_cache_thr, size, gfp);
> > +}
> > +
> > +#define _desc_cache_get(vq, n, gfp, tp) \
> > +	((tp *)desc_cache_get(vq, (sizeof(tp)), n, gfp))
> > +
> > +#define desc_cache_get_split(vq, n, gfp) \
> > +	_desc_cache_get(vq, n, gfp, struct vring_desc)
> > +
>
> same thing here.
>
> > +static struct vring_desc *alloc_indirect_split(struct vring_virtqueue
*vq,
> >  					       unsigned int total_sg,
> >  					       gfp_t gfp)
> >  {
> > @@ -437,12 +492,12 @@ static struct vring_desc
*alloc_indirect_split(struct virtqueue *_vq,
> >  	 */
> >  	gfp &= ~__GFP_HIGHMEM;
> >
> > -	desc = kmalloc_array(total_sg, sizeof(struct vring_desc), gfp);
> > +	desc = desc_cache_get_split(vq, total_sg, gfp);
> >  	if (!desc)
> >  		return NULL;
> >
> >  	for (i = 0; i < total_sg; i++)
> > -		desc[i].next = cpu_to_virtio16(_vq->vdev, i + 1);
> > +		desc[i].next = cpu_to_virtio16(vq->vq.vdev, i + 1);
> >  	return desc;
> >  }
> >
> > @@ -508,7 +563,7 @@ static inline int virtqueue_add_split(struct
virtqueue *_vq,
> >  	head = vq->free_head;
> >
> >  	if (virtqueue_use_indirect(_vq, total_sg))
> > -		desc = alloc_indirect_split(_vq, total_sg, gfp);
> > +		desc = alloc_indirect_split(vq, total_sg, gfp);
> >  	else {
> >  		desc = NULL;
> >  		WARN_ON_ONCE(total_sg > vq->split.vring.num &&
!vq->indirect);
> > @@ -652,7 +707,7 @@ static inline int virtqueue_add_split(struct
virtqueue *_vq,
> >  	}
> >
> >  	if (indirect)
> > -		kfree(desc);
> > +		desc_cache_put(vq, desc, total_sg);
> >
> >  	END_USE(vq);
> >  	return -ENOMEM;
> > @@ -717,7 +772,7 @@ static void detach_buf_split(struct
vring_virtqueue *vq, unsigned int head,
> >  	if (vq->indirect) {
> >  		struct vring_desc *indir_desc > >  			
vq->split.desc_state[head].indir_desc;
> > -		u32 len;
> > +		u32 len, n;
> >
> >  		/* Free the indirect table, if any, now that it's unmapped. */
> >  		if (!indir_desc)
> > @@ -729,10 +784,12 @@ static void detach_buf_split(struct
vring_virtqueue *vq, unsigned int head,
> >  				VRING_DESC_F_INDIRECT));
> >  		BUG_ON(len == 0 || len % sizeof(struct vring_desc));
> >
> > -		for (j = 0; j < len / sizeof(struct vring_desc); j++)
> > +		n = len / sizeof(struct vring_desc);
> > +
> > +		for (j = 0; j < n; j++)
> >  			vring_unmap_one_split_indirect(vq, &indir_desc[j]);
> >
> > -		kfree(indir_desc);
> > +		desc_cache_put(vq, indir_desc, n);
> >  		vq->split.desc_state[head].indir_desc = NULL;
> >  	} else if (ctx) {
> >  		*ctx = vq->split.desc_state[head].indir_desc;
> > @@ -2199,6 +2256,9 @@ struct virtqueue *__vring_new_virtqueue(unsigned
int index,
> >  	vq->indirect = virtio_has_feature(vdev,
VIRTIO_RING_F_INDIRECT_DESC) &&
> >  		!context;
> >  	vq->event = virtio_has_feature(vdev, VIRTIO_RING_F_EVENT_IDX);
> > +	vq->desc_cache_thr = vdev->desc_cache_thr;
> > +
> > +	INIT_LIST_HEAD(&vq->desc_cache);
> >
> >  	if (virtio_has_feature(vdev, VIRTIO_F_ORDER_PLATFORM))
> >  		vq->weak_barriers = false;
>
> So e.g. for rx, we are wasting memory since indirect isn't used.
Yes, thank you for pointing this out. I ignore this. So pls ignore v4 with
pre-alloc cache.

Thanks.
>
>
> > @@ -2329,6 +2389,7 @@ void vring_del_virtqueue(struct virtqueue *_vq)
> >  	if (!vq->packed_ring) {
> >  		kfree(vq->split.desc_state);
> >  		kfree(vq->split.desc_extra);
> > +		desc_cache_free(&vq->desc_cache);
> >  	}
> >  	kfree(vq);
> >  }
> > diff --git a/include/linux/virtio.h b/include/linux/virtio.h
> > index 41edbc01ffa4..bda6f9853e97 100644
> > --- a/include/linux/virtio.h
> > +++ b/include/linux/virtio.h
> > @@ -118,6 +118,7 @@ struct virtio_device {
> >  	struct list_head vqs;
> >  	u64 features;
> >  	void *priv;
> > +	u32 desc_cache_thr;
> >  };
> >
> >  static inline struct virtio_device *dev_to_virtio(struct device
*_dev)
> > @@ -130,6 +131,19 @@ int register_virtio_device(struct virtio_device
*dev);
> >  void unregister_virtio_device(struct virtio_device *dev);
> >  bool is_virtio_device(struct device *dev);
> >
> > +/**
> > + * virtio_set_desc_cache - set virtio ring desc cache threshold
> > + *
> > + * virtio will cache the allocated indirect desc.
> > + *
> > + * This function must be called before find_vqs.
> > + *
> > + * @thr:
> > + *    0   - disable desc cache
> > + *    > 0 - enable desc cache. As the threshold of the desc cache.
> > + */
> > +void virtio_set_desc_cache(struct virtio_device *dev, u32 thr);
> > +
> >  void virtio_break_device(struct virtio_device *dev);
> >
> >  void virtio_config_changed(struct virtio_device *dev);
> > --
> > 2.31.0
>

On Sun, 31 Oct 2021 10:46:12 -0400, Michael S. Tsirkin <mst at redhat.com>
wrote:
> On Thu, Oct 28, 2021 at 06:49:17PM +0800, Xuan Zhuo wrote:
> > In the case of using indirect, indirect desc must be allocated and
> > released each time, which increases a lot of cpu overhead.
> >
> > Here, a cache is added for indirect. If the number of indirect desc to
be
> > applied for is less than VIRT_QUEUE_CACHE_DESC_NUM, the desc array
with
> > the size of VIRT_QUEUE_CACHE_DESC_NUM is fixed and cached for reuse.
> >
> > Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com>
>
> What bothers me here is what happens if cache gets
> filled on one numa node, then used on another?
>
>
> > ---
> >  drivers/virtio/virtio.c      |  6 +++
> >  drivers/virtio/virtio_ring.c | 77
++++++++++++++++++++++++++++++++----
> >  include/linux/virtio.h       | 14 +++++++
> >  3 files changed, 89 insertions(+), 8 deletions(-)
> >
> > diff --git a/drivers/virtio/virtio.c b/drivers/virtio/virtio.c
> > index 0a5b54034d4b..1047149ac2a4 100644
> > --- a/drivers/virtio/virtio.c
> > +++ b/drivers/virtio/virtio.c
> > @@ -431,6 +431,12 @@ bool is_virtio_device(struct device *dev)
> >  }
> >  EXPORT_SYMBOL_GPL(is_virtio_device);
> >
> > +void virtio_set_desc_cache(struct virtio_device *dev, u32 thr)
> > +{
> > +	dev->desc_cache_thr = thr;
> > +}
> > +EXPORT_SYMBOL_GPL(virtio_set_desc_cache);
> > +
> >  void unregister_virtio_device(struct virtio_device *dev)
> >  {
> >  	int index = dev->index; /* save for after device release */
> > diff --git a/drivers/virtio/virtio_ring.c
b/drivers/virtio/virtio_ring.c
> > index dd95dfd85e98..0ebcd4f12d3b 100644
> > --- a/drivers/virtio/virtio_ring.c
> > +++ b/drivers/virtio/virtio_ring.c
> > @@ -117,6 +117,15 @@ struct vring_virtqueue {
> >  	/* Hint for event idx: already triggered no need to disable. */
> >  	bool event_triggered;
> >
> > +	/* desc cache threshold
> > +	 *    0   - disable desc cache
> > +	 *    > 0 - enable desc cache. As the threshold of the desc
cache.
> > +	 */
> > +	u32 desc_cache_thr;
>
> not really descriptive. also pls eschew abbreviation.
>
> > +
> > +	/* desc cache chain */
> > +	struct list_head desc_cache;
>
> hmm this puts extra pressure on cache. you never need to drop
> things in the middle. llist_head would be better I
> think ... no?
In fact, I did not increase the allocated space for list_head.

use as desc array: | vring_desc | vring_desc | vring_desc | vring_desc |
use as queue item: | list_head ........................................|

Thanks.
>
>
> > +
> >  	union {
> >  		/* Available for split ring */
> >  		struct {
> > @@ -423,7 +432,53 @@ static unsigned int vring_unmap_one_split(const
struct vring_virtqueue *vq,
> >  	return extra[i].next;
> >  }
> >
> > -static struct vring_desc *alloc_indirect_split(struct virtqueue *_vq,
> > +static void desc_cache_free(struct list_head *head)
> > +{
> > +	struct list_head *n, *pos;
> > +
> > +	BUILD_BUG_ON(sizeof(struct list_head) > sizeof(struct
vring_desc));
> > +	BUILD_BUG_ON(sizeof(struct list_head) > sizeof(struct
vring_packed_desc));
> > +
> > +	list_for_each_prev_safe(pos, n, head)
> > +		kfree(pos);
> > +}
> > +
> > +static void __desc_cache_put(struct vring_virtqueue *vq,
> > +			     struct list_head *node, int n)
> > +{
> > +	if (n <= vq->desc_cache_thr)
> > +		list_add(node, &vq->desc_cache);
> > +	else
> > +		kfree(node);
>
> this bothers me. Do we really need a full VQ's worth of
> indirect descriptors? Can't we set a limit on how many
> are used?
>
>
> > +}
> > +
> > +#define desc_cache_put(vq, desc, n) \
> > +	__desc_cache_put(vq, (struct list_head *)desc, n)
>
> replace with an inline function pls. in fact we dont need
> __desc_cache_put at all.
>
>
> > +
> > +static void *desc_cache_get(struct vring_virtqueue *vq,
> > +			    int size, int n, gfp_t gfp)
> > +{
> > +	struct list_head *node;
> > +
> > +	if (n > vq->desc_cache_thr)
> > +		return kmalloc_array(n, size, gfp);
> > +
> > +	if (!list_empty(&vq->desc_cache)) {
> > +		node = vq->desc_cache.next;
> > +		list_del(node);
> > +		return node;
> > +	}
> > +
> > +	return kmalloc_array(vq->desc_cache_thr, size, gfp);
> > +}
> > +
> > +#define _desc_cache_get(vq, n, gfp, tp) \
> > +	((tp *)desc_cache_get(vq, (sizeof(tp)), n, gfp))
> > +
> > +#define desc_cache_get_split(vq, n, gfp) \
> > +	_desc_cache_get(vq, n, gfp, struct vring_desc)
> > +
>
> same thing here.
>
> > +static struct vring_desc *alloc_indirect_split(struct vring_virtqueue
*vq,
> >  					       unsigned int total_sg,
> >  					       gfp_t gfp)
> >  {
> > @@ -437,12 +492,12 @@ static struct vring_desc
*alloc_indirect_split(struct virtqueue *_vq,
> >  	 */
> >  	gfp &= ~__GFP_HIGHMEM;
> >
> > -	desc = kmalloc_array(total_sg, sizeof(struct vring_desc), gfp);
> > +	desc = desc_cache_get_split(vq, total_sg, gfp);
> >  	if (!desc)
> >  		return NULL;
> >
> >  	for (i = 0; i < total_sg; i++)
> > -		desc[i].next = cpu_to_virtio16(_vq->vdev, i + 1);
> > +		desc[i].next = cpu_to_virtio16(vq->vq.vdev, i + 1);
> >  	return desc;
> >  }
> >
> > @@ -508,7 +563,7 @@ static inline int virtqueue_add_split(struct
virtqueue *_vq,
> >  	head = vq->free_head;
> >
> >  	if (virtqueue_use_indirect(_vq, total_sg))
> > -		desc = alloc_indirect_split(_vq, total_sg, gfp);
> > +		desc = alloc_indirect_split(vq, total_sg, gfp);
> >  	else {
> >  		desc = NULL;
> >  		WARN_ON_ONCE(total_sg > vq->split.vring.num &&
!vq->indirect);
> > @@ -652,7 +707,7 @@ static inline int virtqueue_add_split(struct
virtqueue *_vq,
> >  	}
> >
> >  	if (indirect)
> > -		kfree(desc);
> > +		desc_cache_put(vq, desc, total_sg);
> >
> >  	END_USE(vq);
> >  	return -ENOMEM;
> > @@ -717,7 +772,7 @@ static void detach_buf_split(struct
vring_virtqueue *vq, unsigned int head,
> >  	if (vq->indirect) {
> >  		struct vring_desc *indir_desc > >  			
vq->split.desc_state[head].indir_desc;
> > -		u32 len;
> > +		u32 len, n;
> >
> >  		/* Free the indirect table, if any, now that it's unmapped. */
> >  		if (!indir_desc)
> > @@ -729,10 +784,12 @@ static void detach_buf_split(struct
vring_virtqueue *vq, unsigned int head,
> >  				VRING_DESC_F_INDIRECT));
> >  		BUG_ON(len == 0 || len % sizeof(struct vring_desc));
> >
> > -		for (j = 0; j < len / sizeof(struct vring_desc); j++)
> > +		n = len / sizeof(struct vring_desc);
> > +
> > +		for (j = 0; j < n; j++)
> >  			vring_unmap_one_split_indirect(vq, &indir_desc[j]);
> >
> > -		kfree(indir_desc);
> > +		desc_cache_put(vq, indir_desc, n);
> >  		vq->split.desc_state[head].indir_desc = NULL;
> >  	} else if (ctx) {
> >  		*ctx = vq->split.desc_state[head].indir_desc;
> > @@ -2199,6 +2256,9 @@ struct virtqueue *__vring_new_virtqueue(unsigned
int index,
> >  	vq->indirect = virtio_has_feature(vdev,
VIRTIO_RING_F_INDIRECT_DESC) &&
> >  		!context;
> >  	vq->event = virtio_has_feature(vdev, VIRTIO_RING_F_EVENT_IDX);
> > +	vq->desc_cache_thr = vdev->desc_cache_thr;
> > +
> > +	INIT_LIST_HEAD(&vq->desc_cache);
> >
> >  	if (virtio_has_feature(vdev, VIRTIO_F_ORDER_PLATFORM))
> >  		vq->weak_barriers = false;
>
> So e.g. for rx, we are wasting memory since indirect isn't used.
>
>
> > @@ -2329,6 +2389,7 @@ void vring_del_virtqueue(struct virtqueue *_vq)
> >  	if (!vq->packed_ring) {
> >  		kfree(vq->split.desc_state);
> >  		kfree(vq->split.desc_extra);
> > +		desc_cache_free(&vq->desc_cache);
> >  	}
> >  	kfree(vq);
> >  }
> > diff --git a/include/linux/virtio.h b/include/linux/virtio.h
> > index 41edbc01ffa4..bda6f9853e97 100644
> > --- a/include/linux/virtio.h
> > +++ b/include/linux/virtio.h
> > @@ -118,6 +118,7 @@ struct virtio_device {
> >  	struct list_head vqs;
> >  	u64 features;
> >  	void *priv;
> > +	u32 desc_cache_thr;
> >  };
> >
> >  static inline struct virtio_device *dev_to_virtio(struct device
*_dev)
> > @@ -130,6 +131,19 @@ int register_virtio_device(struct virtio_device
*dev);
> >  void unregister_virtio_device(struct virtio_device *dev);
> >  bool is_virtio_device(struct device *dev);
> >
> > +/**
> > + * virtio_set_desc_cache - set virtio ring desc cache threshold
> > + *
> > + * virtio will cache the allocated indirect desc.
> > + *
> > + * This function must be called before find_vqs.
> > + *
> > + * @thr:
> > + *    0   - disable desc cache
> > + *    > 0 - enable desc cache. As the threshold of the desc cache.
> > + */
> > +void virtio_set_desc_cache(struct virtio_device *dev, u32 thr);
> > +
> >  void virtio_break_device(struct virtio_device *dev);
> >
> >  void virtio_config_changed(struct virtio_device *dev);
> > --
> > 2.31.0
>