* Re: [PATCH 1/2] virtio_ring: remove unnecessary to_vvq call in vring hot path
[not found] <20220328105817.1028065-1-xianting.tian@linux.alibaba.com>
@ 2022-03-29 4:56 ` Jason Wang
2022-03-29 7:49 ` Stefano Garzarella
[not found] ` <20220328105817.1028065-2-xianting.tian@linux.alibaba.com>
2 siblings, 0 replies; 5+ messages in thread
From: Jason Wang @ 2022-03-29 4:56 UTC (permalink / raw)
To: Xianting Tian; +Cc: virtualization, linux-kernel, mst
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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https://lists.linuxfoundation.org/mailman/listinfo/virtualization
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH 2/2] virtio_ring: add unlikely annotation for free descs check
[not found] ` <20220328105817.1028065-2-xianting.tian@linux.alibaba.com>
@ 2022-03-29 4:57 ` Jason Wang
2022-03-29 7:50 ` Stefano Garzarella
1 sibling, 0 replies; 5+ messages in thread
From: Jason Wang @ 2022-03-29 4:57 UTC (permalink / raw)
To: Xianting Tian; +Cc: virtualization, linux-kernel, mst
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
>
_______________________________________________
Virtualization mailing list
Virtualization@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/virtualization
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH 1/2] virtio_ring: remove unnecessary to_vvq call in vring hot path
[not found] <20220328105817.1028065-1-xianting.tian@linux.alibaba.com>
2022-03-29 4:56 ` [PATCH 1/2] virtio_ring: remove unnecessary to_vvq call in vring hot path Jason Wang
@ 2022-03-29 7:49 ` Stefano Garzarella
[not found] ` <20220328105817.1028065-2-xianting.tian@linux.alibaba.com>
2 siblings, 0 replies; 5+ messages in thread
From: Stefano Garzarella @ 2022-03-29 7:49 UTC (permalink / raw)
To: Xianting Tian; +Cc: virtualization, linux-kernel, mst
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
>
_______________________________________________
Virtualization mailing list
Virtualization@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/virtualization
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH 2/2] virtio_ring: add unlikely annotation for free descs check
[not found] ` <20220328105817.1028065-2-xianting.tian@linux.alibaba.com>
2022-03-29 4:57 ` [PATCH 2/2] virtio_ring: add unlikely annotation for free descs check Jason Wang
@ 2022-03-29 7:50 ` Stefano Garzarella
[not found] ` <073dc28b-1707-cd04-daba-13aa4fac5a85@linux.alibaba.com>
1 sibling, 1 reply; 5+ messages in thread
From: Stefano Garzarella @ 2022-03-29 7:50 UTC (permalink / raw)
To: Xianting Tian; +Cc: virtualization, linux-kernel, mst
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
>
_______________________________________________
Virtualization mailing list
Virtualization@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/virtualization
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH 2/2] virtio_ring: add unlikely annotation for free descs check
[not found] ` <073dc28b-1707-cd04-daba-13aa4fac5a85@linux.alibaba.com>
@ 2022-04-04 16:27 ` Michael S. Tsirkin
0 siblings, 0 replies; 5+ messages in thread
From: Michael S. Tsirkin @ 2022-04-04 16:27 UTC (permalink / raw)
To: Xianting Tian; +Cc: virtualization, linux-kernel
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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Virtualization mailing list
Virtualization@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/virtualization
^ permalink raw reply [flat|nested] 5+ messages in thread
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[not found] <20220328105817.1028065-1-xianting.tian@linux.alibaba.com>
2022-03-29 4:56 ` [PATCH 1/2] virtio_ring: remove unnecessary to_vvq call in vring hot path Jason Wang
2022-03-29 7:49 ` Stefano Garzarella
[not found] ` <20220328105817.1028065-2-xianting.tian@linux.alibaba.com>
2022-03-29 4:57 ` [PATCH 2/2] virtio_ring: add unlikely annotation for free descs check Jason Wang
2022-03-29 7:50 ` Stefano Garzarella
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