[PATCH 1/2] virtio_ring: remove unnecessary to_vvq call in vring hot path

[PATCH 1/2] virtio_ring: remove unnecessary to_vvq call in vring hot path

[Xianting Tian]

It passes '_vq' to virtqueue_use_indirect(), which still calls
to_vvq to get 'vq', let's directly pass 'vq'. It can avoid
unnecessary call of to_vvq in hot path.

Signed-off-by: Xianting Tian <xianting.tian@linux.alibaba.com>
---
 drivers/virtio/virtio_ring.c | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index 962f1477b1fa..d597fc0874ec 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -205,11 +205,9 @@ struct vring_virtqueue {
 
 #define to_vvq(_vq) container_of(_vq, struct vring_virtqueue, vq)
 
-static inline bool virtqueue_use_indirect(struct virtqueue *_vq,
+static inline bool virtqueue_use_indirect(struct vring_virtqueue *vq,
 					  unsigned int total_sg)
 {
-	struct vring_virtqueue *vq = to_vvq(_vq);
-
 	/*
 	 * If the host supports indirect descriptor tables, and we have multiple
 	 * buffers, then go indirect. FIXME: tune this threshold
@@ -507,7 +505,7 @@ static inline int virtqueue_add_split(struct virtqueue *_vq,
 
 	head = vq->free_head;
 
-	if (virtqueue_use_indirect(_vq, total_sg))
+	if (virtqueue_use_indirect(vq, total_sg))
 		desc = alloc_indirect_split(_vq, total_sg, gfp);
 	else {
 		desc = NULL;
@@ -1194,7 +1192,7 @@ static inline int virtqueue_add_packed(struct virtqueue *_vq,
 
 	BUG_ON(total_sg == 0);
 
-	if (virtqueue_use_indirect(_vq, total_sg)) {
+	if (virtqueue_use_indirect(vq, total_sg)) {
 		err = virtqueue_add_indirect_packed(vq, sgs, total_sg, out_sgs,
 						    in_sgs, data, gfp);
 		if (err != -ENOMEM) {
-- 
2.17.1

[PATCH 2/2] virtio_ring: add unlikely annotation for free descs check

[Xianting Tian]

The 'if (vq->vq.num_free < descs_used)' check will almost always be false.

Signed-off-by: Xianting Tian <xianting.tian@linux.alibaba.com>
---
 drivers/virtio/virtio_ring.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index d597fc0874ec..ab6d5f0cb579 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -525,7 +525,7 @@ static inline int virtqueue_add_split(struct virtqueue *_vq,
 		descs_used = total_sg;
 	}
 
-	if (vq->vq.num_free < descs_used) {
+	if (unlikely(vq->vq.num_free < descs_used)) {
 		pr_debug("Can't add buf len %i - avail = %i\n",
 			 descs_used, vq->vq.num_free);
 		/* FIXME: for historical reasons, we force a notify here if
-- 
2.17.1

Re: [PATCH 1/2] virtio_ring: remove unnecessary to_vvq call in vring hot path

[Jason Wang]

On Mon, Mar 28, 2022 at 6:58 PM Xianting Tian
<xianting.tian@linux.alibaba.com> wrote:
>
> It passes '_vq' to virtqueue_use_indirect(), which still calls
> to_vvq to get 'vq', let's directly pass 'vq'. It can avoid
> unnecessary call of to_vvq in hot path.
>
> Signed-off-by: Xianting Tian <xianting.tian@linux.alibaba.com>

Acked-by: Jason Wang <jasowang@redhat.com>

> ---
>  drivers/virtio/virtio_ring.c | 8 +++-----
>  1 file changed, 3 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
> index 962f1477b1fa..d597fc0874ec 100644
> --- a/drivers/virtio/virtio_ring.c
> +++ b/drivers/virtio/virtio_ring.c
> @@ -205,11 +205,9 @@ struct vring_virtqueue {
>
>  #define to_vvq(_vq) container_of(_vq, struct vring_virtqueue, vq)
>
> -static inline bool virtqueue_use_indirect(struct virtqueue *_vq,
> +static inline bool virtqueue_use_indirect(struct vring_virtqueue *vq,
>                                           unsigned int total_sg)
>  {
> -       struct vring_virtqueue *vq = to_vvq(_vq);
> -
>         /*
>          * If the host supports indirect descriptor tables, and we have multiple
>          * buffers, then go indirect. FIXME: tune this threshold
> @@ -507,7 +505,7 @@ static inline int virtqueue_add_split(struct virtqueue *_vq,
>
>         head = vq->free_head;
>
> -       if (virtqueue_use_indirect(_vq, total_sg))
> +       if (virtqueue_use_indirect(vq, total_sg))
>                 desc = alloc_indirect_split(_vq, total_sg, gfp);
>         else {
>                 desc = NULL;
> @@ -1194,7 +1192,7 @@ static inline int virtqueue_add_packed(struct virtqueue *_vq,
>
>         BUG_ON(total_sg == 0);
>
> -       if (virtqueue_use_indirect(_vq, total_sg)) {
> +       if (virtqueue_use_indirect(vq, total_sg)) {
>                 err = virtqueue_add_indirect_packed(vq, sgs, total_sg, out_sgs,
>                                                     in_sgs, data, gfp);
>                 if (err != -ENOMEM) {
> --
> 2.17.1
>

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Re: [PATCH 1/2] virtio_ring: remove unnecessary to_vvq call in vring hot path

[Jason Wang]

On Mon, Mar 28, 2022 at 6:58 PM Xianting Tian
<xianting.tian@linux.alibaba.com> wrote:
>
> It passes '_vq' to virtqueue_use_indirect(), which still calls
> to_vvq to get 'vq', let's directly pass 'vq'. It can avoid
> unnecessary call of to_vvq in hot path.
>
> Signed-off-by: Xianting Tian <xianting.tian@linux.alibaba.com>

Acked-by: Jason Wang <jasowang@redhat.com>

> ---
>  drivers/virtio/virtio_ring.c | 8 +++-----
>  1 file changed, 3 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
> index 962f1477b1fa..d597fc0874ec 100644
> --- a/drivers/virtio/virtio_ring.c
> +++ b/drivers/virtio/virtio_ring.c
> @@ -205,11 +205,9 @@ struct vring_virtqueue {
>
>  #define to_vvq(_vq) container_of(_vq, struct vring_virtqueue, vq)
>
> -static inline bool virtqueue_use_indirect(struct virtqueue *_vq,
> +static inline bool virtqueue_use_indirect(struct vring_virtqueue *vq,
>                                           unsigned int total_sg)
>  {
> -       struct vring_virtqueue *vq = to_vvq(_vq);
> -
>         /*
>          * If the host supports indirect descriptor tables, and we have multiple
>          * buffers, then go indirect. FIXME: tune this threshold
> @@ -507,7 +505,7 @@ static inline int virtqueue_add_split(struct virtqueue *_vq,
>
>         head = vq->free_head;
>
> -       if (virtqueue_use_indirect(_vq, total_sg))
> +       if (virtqueue_use_indirect(vq, total_sg))
>                 desc = alloc_indirect_split(_vq, total_sg, gfp);
>         else {
>                 desc = NULL;
> @@ -1194,7 +1192,7 @@ static inline int virtqueue_add_packed(struct virtqueue *_vq,
>
>         BUG_ON(total_sg == 0);
>
> -       if (virtqueue_use_indirect(_vq, total_sg)) {
> +       if (virtqueue_use_indirect(vq, total_sg)) {
>                 err = virtqueue_add_indirect_packed(vq, sgs, total_sg, out_sgs,
>                                                     in_sgs, data, gfp);
>                 if (err != -ENOMEM) {
> --
> 2.17.1
>

Re: [PATCH 2/2] virtio_ring: add unlikely annotation for free descs check

[Jason Wang]

On Mon, Mar 28, 2022 at 6:58 PM Xianting Tian
<xianting.tian@linux.alibaba.com> wrote:
>
> The 'if (vq->vq.num_free < descs_used)' check will almost always be false.
>
> Signed-off-by: Xianting Tian <xianting.tian@linux.alibaba.com>

Acked-by: Jason Wang <jasowang@redhat.com>

> ---
>  drivers/virtio/virtio_ring.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
> index d597fc0874ec..ab6d5f0cb579 100644
> --- a/drivers/virtio/virtio_ring.c
> +++ b/drivers/virtio/virtio_ring.c
> @@ -525,7 +525,7 @@ static inline int virtqueue_add_split(struct virtqueue *_vq,
>                 descs_used = total_sg;
>         }
>
> -       if (vq->vq.num_free < descs_used) {
> +       if (unlikely(vq->vq.num_free < descs_used)) {
>                 pr_debug("Can't add buf len %i - avail = %i\n",
>                          descs_used, vq->vq.num_free);
>                 /* FIXME: for historical reasons, we force a notify here if
> --
> 2.17.1
>

Re: [PATCH 2/2] virtio_ring: add unlikely annotation for free descs check

[Jason Wang]

On Mon, Mar 28, 2022 at 6:58 PM Xianting Tian
<xianting.tian@linux.alibaba.com> wrote:
>
> The 'if (vq->vq.num_free < descs_used)' check will almost always be false.
>
> Signed-off-by: Xianting Tian <xianting.tian@linux.alibaba.com>

Acked-by: Jason Wang <jasowang@redhat.com>

> ---
>  drivers/virtio/virtio_ring.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
> index d597fc0874ec..ab6d5f0cb579 100644
> --- a/drivers/virtio/virtio_ring.c
> +++ b/drivers/virtio/virtio_ring.c
> @@ -525,7 +525,7 @@ static inline int virtqueue_add_split(struct virtqueue *_vq,
>                 descs_used = total_sg;
>         }
>
> -       if (vq->vq.num_free < descs_used) {
> +       if (unlikely(vq->vq.num_free < descs_used)) {
>                 pr_debug("Can't add buf len %i - avail = %i\n",
>                          descs_used, vq->vq.num_free);
>                 /* FIXME: for historical reasons, we force a notify here if
> --
> 2.17.1
>

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Re: [PATCH 1/2] virtio_ring: remove unnecessary to_vvq call in vring hot path

[Stefano Garzarella]

On Mon, Mar 28, 2022 at 06:58:16PM +0800, Xianting Tian wrote:
>It passes '_vq' to virtqueue_use_indirect(), which still calls
>to_vvq to get 'vq', let's directly pass 'vq'. It can avoid
>unnecessary call of to_vvq in hot path.
>
>Signed-off-by: Xianting Tian <xianting.tian@linux.alibaba.com>
>---
> drivers/virtio/virtio_ring.c | 8 +++-----
> 1 file changed, 3 insertions(+), 5 deletions(-)

Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>

>
>diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
>index 962f1477b1fa..d597fc0874ec 100644
>--- a/drivers/virtio/virtio_ring.c
>+++ b/drivers/virtio/virtio_ring.c
>@@ -205,11 +205,9 @@ struct vring_virtqueue {
>
> #define to_vvq(_vq) container_of(_vq, struct vring_virtqueue, vq)
>
>-static inline bool virtqueue_use_indirect(struct virtqueue *_vq,
>+static inline bool virtqueue_use_indirect(struct vring_virtqueue *vq,
> 					  unsigned int total_sg)
> {
>-	struct vring_virtqueue *vq = to_vvq(_vq);
>-
> 	/*
> 	 * If the host supports indirect descriptor tables, and we have multiple
> 	 * buffers, then go indirect. FIXME: tune this threshold
>@@ -507,7 +505,7 @@ static inline int virtqueue_add_split(struct virtqueue *_vq,
>
> 	head = vq->free_head;
>
>-	if (virtqueue_use_indirect(_vq, total_sg))
>+	if (virtqueue_use_indirect(vq, total_sg))
> 		desc = alloc_indirect_split(_vq, total_sg, gfp);
> 	else {
> 		desc = NULL;
>@@ -1194,7 +1192,7 @@ static inline int virtqueue_add_packed(struct virtqueue *_vq,
>
> 	BUG_ON(total_sg == 0);
>
>-	if (virtqueue_use_indirect(_vq, total_sg)) {
>+	if (virtqueue_use_indirect(vq, total_sg)) {
> 		err = virtqueue_add_indirect_packed(vq, sgs, total_sg, out_sgs,
> 						    in_sgs, data, gfp);
> 		if (err != -ENOMEM) {
>-- 
>2.17.1
>

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Re: [PATCH 1/2] virtio_ring: remove unnecessary to_vvq call in vring hot path

[Stefano Garzarella]

On Mon, Mar 28, 2022 at 06:58:16PM +0800, Xianting Tian wrote:
>It passes '_vq' to virtqueue_use_indirect(), which still calls
>to_vvq to get 'vq', let's directly pass 'vq'. It can avoid
>unnecessary call of to_vvq in hot path.
>
>Signed-off-by: Xianting Tian <xianting.tian@linux.alibaba.com>
>---
> drivers/virtio/virtio_ring.c | 8 +++-----
> 1 file changed, 3 insertions(+), 5 deletions(-)

Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>

>
>diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
>index 962f1477b1fa..d597fc0874ec 100644
>--- a/drivers/virtio/virtio_ring.c
>+++ b/drivers/virtio/virtio_ring.c
>@@ -205,11 +205,9 @@ struct vring_virtqueue {
>
> #define to_vvq(_vq) container_of(_vq, struct vring_virtqueue, vq)
>
>-static inline bool virtqueue_use_indirect(struct virtqueue *_vq,
>+static inline bool virtqueue_use_indirect(struct vring_virtqueue *vq,
> 					  unsigned int total_sg)
> {
>-	struct vring_virtqueue *vq = to_vvq(_vq);
>-
> 	/*
> 	 * If the host supports indirect descriptor tables, and we have multiple
> 	 * buffers, then go indirect. FIXME: tune this threshold
>@@ -507,7 +505,7 @@ static inline int virtqueue_add_split(struct virtqueue *_vq,
>
> 	head = vq->free_head;
>
>-	if (virtqueue_use_indirect(_vq, total_sg))
>+	if (virtqueue_use_indirect(vq, total_sg))
> 		desc = alloc_indirect_split(_vq, total_sg, gfp);
> 	else {
> 		desc = NULL;
>@@ -1194,7 +1192,7 @@ static inline int virtqueue_add_packed(struct virtqueue *_vq,
>
> 	BUG_ON(total_sg == 0);
>
>-	if (virtqueue_use_indirect(_vq, total_sg)) {
>+	if (virtqueue_use_indirect(vq, total_sg)) {
> 		err = virtqueue_add_indirect_packed(vq, sgs, total_sg, out_sgs,
> 						    in_sgs, data, gfp);
> 		if (err != -ENOMEM) {
>-- 
>2.17.1
>

Re: [PATCH 2/2] virtio_ring: add unlikely annotation for free descs check

[Stefano Garzarella]

On Mon, Mar 28, 2022 at 06:58:17PM +0800, Xianting Tian wrote:
>The 'if (vq->vq.num_free < descs_used)' check will almost always be false.
>
>Signed-off-by: Xianting Tian <xianting.tian@linux.alibaba.com>
>---
> drivers/virtio/virtio_ring.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)

Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>

>
>diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
>index d597fc0874ec..ab6d5f0cb579 100644
>--- a/drivers/virtio/virtio_ring.c
>+++ b/drivers/virtio/virtio_ring.c
>@@ -525,7 +525,7 @@ static inline int virtqueue_add_split(struct virtqueue *_vq,
> 		descs_used = total_sg;
> 	}
>
>-	if (vq->vq.num_free < descs_used) {
>+	if (unlikely(vq->vq.num_free < descs_used)) {
> 		pr_debug("Can't add buf len %i - avail = %i\n",
> 			 descs_used, vq->vq.num_free);
> 		/* FIXME: for historical reasons, we force a notify here if
>-- 
>2.17.1
>

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Re: [PATCH 2/2] virtio_ring: add unlikely annotation for free descs check

[Stefano Garzarella]

On Mon, Mar 28, 2022 at 06:58:17PM +0800, Xianting Tian wrote:
>The 'if (vq->vq.num_free < descs_used)' check will almost always be false.
>
>Signed-off-by: Xianting Tian <xianting.tian@linux.alibaba.com>
>---
> drivers/virtio/virtio_ring.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)

Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>

>
>diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
>index d597fc0874ec..ab6d5f0cb579 100644
>--- a/drivers/virtio/virtio_ring.c
>+++ b/drivers/virtio/virtio_ring.c
>@@ -525,7 +525,7 @@ static inline int virtqueue_add_split(struct virtqueue *_vq,
> 		descs_used = total_sg;
> 	}
>
>-	if (vq->vq.num_free < descs_used) {
>+	if (unlikely(vq->vq.num_free < descs_used)) {
> 		pr_debug("Can't add buf len %i - avail = %i\n",
> 			 descs_used, vq->vq.num_free);
> 		/* FIXME: for historical reasons, we force a notify here if
>-- 
>2.17.1
>

Re: [PATCH 2/2] virtio_ring: add unlikely annotation for free descs check

[Xianting Tian]

I can't find it in next branch, will you apply this patch?

在 2022/3/29 下午3:50, Stefano Garzarella 写道:
> On Mon, Mar 28, 2022 at 06:58:17PM +0800, Xianting Tian wrote:
>> The 'if (vq->vq.num_free < descs_used)' check will almost always be 
>> false.
>>
>> Signed-off-by: Xianting Tian <xianting.tian@linux.alibaba.com>
>> ---
>> drivers/virtio/virtio_ring.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
>
>>
>> diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
>> index d597fc0874ec..ab6d5f0cb579 100644
>> --- a/drivers/virtio/virtio_ring.c
>> +++ b/drivers/virtio/virtio_ring.c
>> @@ -525,7 +525,7 @@ static inline int virtqueue_add_split(struct 
>> virtqueue *_vq,
>>         descs_used = total_sg;
>>     }
>>
>> -    if (vq->vq.num_free < descs_used) {
>> +    if (unlikely(vq->vq.num_free < descs_used)) {
>>         pr_debug("Can't add buf len %i - avail = %i\n",
>>              descs_used, vq->vq.num_free);
>>         /* FIXME: for historical reasons, we force a notify here if
>> -- 
>> 2.17.1
>>

Re: [PATCH 2/2] virtio_ring: add unlikely annotation for free descs check

[Michael S. Tsirkin]

On Mon, Apr 04, 2022 at 11:11:16PM +0800, Xianting Tian wrote:
> I can't find it in next branch, will you apply this patch?

yes, thanks!

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Re: [PATCH 2/2] virtio_ring: add unlikely annotation for free descs check

[Michael S. Tsirkin]

On Mon, Apr 04, 2022 at 11:11:16PM +0800, Xianting Tian wrote:
> I can't find it in next branch, will you apply this patch?

yes, thanks!