linux-kernel - Re: [PATCH vhost v2 10/10] vdpa/mlx5: Parallelize VQ suspend/resume for CVQ MQ command

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Message-ID: <CAJaqyWd0Gwap1253WegSHSADw2ymZ81vvwuTgVMCTSH5-gddbg@mail.gmail.com>
Date: Wed, 28 Aug 2024 14:59:05 +0200
From: Eugenio Perez Martin <eperezma@...hat.com>
To: Dragos Tatulea <dtatulea@...dia.com>
Cc: "Michael S . Tsirkin" <mst@...hat.com>, Jason Wang <jasowang@...hat.com>, 
	virtualization@...ts.linux-foundation.org, Si-Wei Liu <si-wei.liu@...cle.com>, 
	Saeed Mahameed <saeedm@...dia.com>, Leon Romanovsky <leon@...nel.org>, kvm@...r.kernel.org, 
	linux-kernel@...r.kernel.org, Gal Pressman <gal@...dia.com>, 
	Parav Pandit <parav@...dia.com>, Xuan Zhuo <xuanzhuo@...ux.alibaba.com>, 
	Tariq Toukan <tariqt@...dia.com>
Subject: Re: [PATCH vhost v2 10/10] vdpa/mlx5: Parallelize VQ suspend/resume
 for CVQ MQ command

On Fri, Aug 16, 2024 at 11:03 AM Dragos Tatulea <dtatulea@...dia.com> wrote:
>
> change_num_qps() is still suspending/resuming VQs one by one.
> This change switches to parallel suspend/resume.
>
> When increasing the number of queues the flow has changed a bit for
> simplicity: the setup_vq() function will always be called before
> resume_vqs(). If the VQ is initialized, setup_vq() will exit early. If
> the VQ is not initialized, setup_vq() will create it and resume_vqs()
> will resume it.
>
> Signed-off-by: Dragos Tatulea <dtatulea@...dia.com>
> Reviewed-by: Tariq Toukan <tariqt@...dia.com>

Acked-by: Eugenio Pérez <eperezma@...hat.com>

> ---
>  drivers/vdpa/mlx5/net/mlx5_vnet.c | 22 ++++++++++++----------
>  1 file changed, 12 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/vdpa/mlx5/net/mlx5_vnet.c b/drivers/vdpa/mlx5/net/mlx5_vnet.c
> index d1a01c229110..822092eccb32 100644
> --- a/drivers/vdpa/mlx5/net/mlx5_vnet.c
> +++ b/drivers/vdpa/mlx5/net/mlx5_vnet.c
> @@ -2229,25 +2229,27 @@ static int change_num_qps(struct mlx5_vdpa_dev *mvdev, int newqps)
>                 if (err)
>                         return err;
>
> -               for (i = cur_vqs - 1; i >= new_vqs; i--) {
> -                       struct mlx5_vdpa_virtqueue *mvq = &ndev->vqs[i];
> -
> -                       if (is_resumable(ndev))
> -                               suspend_vq(ndev, mvq);
> -                       else
> -                               teardown_vq(ndev, mvq);
> +               if (is_resumable(ndev)) {
> +                       suspend_vqs(ndev, new_vqs, cur_vqs - new_vqs);
> +               } else {
> +                       for (i = new_vqs; i < cur_vqs; i++)
> +                               teardown_vq(ndev, &ndev->vqs[i]);
>                 }
>
>                 ndev->cur_num_vqs = new_vqs;
>         } else {
>                 ndev->cur_num_vqs = new_vqs;
> -               for (i = cur_vqs; i < new_vqs; i++) {
> -                       struct mlx5_vdpa_virtqueue *mvq = &ndev->vqs[i];
>
> -                       err = mvq->initialized ? resume_vq(ndev, mvq) : setup_vq(ndev, mvq, true);
> +               for (i = cur_vqs; i < new_vqs; i++) {
> +                       err = setup_vq(ndev, &ndev->vqs[i], false);
>                         if (err)
>                                 goto clean_added;
>                 }
> +
> +               err = resume_vqs(ndev, cur_vqs, new_vqs - cur_vqs);
> +               if (err)
> +                       goto clean_added;
> +
>                 err = modify_rqt(ndev, new_vqs);
>                 if (err)
>                         goto clean_added;
> --
> 2.45.1
>