[Nouveau] [PATCH 2/2] nouveau: Do not add most bo's to the global bo list.

[Emil Velikov]

On 24 February 2015 at 09:01, Maarten Lankhorst
<maarten.lankhorst at ubuntu.com> wrote:
> Only add wrapped bo's and bo's that have been exported through flink or dma-buf.
> This avoids a lock in the common case, and decreases traversal needed for importing
> a dma-buf or flink.
>
> Signed-off-by: Maarten Lankhorst <maarten.lankhorst at ubuntu.com>
> ---
>  nouveau/nouveau.c | 47 +++++++++++++++++++++++------------------------
>  1 file changed, 23 insertions(+), 24 deletions(-)
>
> diff --git a/nouveau/nouveau.c b/nouveau/nouveau.c
> index 1c723b9..d411523 100644
> --- a/nouveau/nouveau.c
> +++ b/nouveau/nouveau.c
> @@ -349,8 +349,8 @@ nouveau_bo_del(struct nouveau_bo *bo)
>         struct nouveau_bo_priv *nvbo = nouveau_bo(bo);
>         struct drm_gem_close req = { bo->handle };
>
> -       pthread_mutex_lock(&nvdev->lock);
> -       if (nvbo->name) {
> +       if (nvbo->head.next) {
> +               pthread_mutex_lock(&nvdev->lock);
>                 if (atomic_read(&nvbo->refcnt) == 0) {
>                         DRMLISTDEL(&nvbo->head);
>                         /*
> @@ -365,8 +365,6 @@ nouveau_bo_del(struct nouveau_bo *bo)
>                 }
>                 pthread_mutex_unlock(&nvdev->lock);
>         } else {
> -               DRMLISTDEL(&nvbo->head);
> -               pthread_mutex_unlock(&nvdev->lock);
>                 drmIoctl(bo->device->fd, DRM_IOCTL_GEM_CLOSE, &req);
>         }
>         if (bo->map)
> @@ -379,7 +377,6 @@ nouveau_bo_new(struct nouveau_device *dev, uint32_t flags, uint32_t align,
>                uint64_t size, union nouveau_bo_config *config,
>                struct nouveau_bo **pbo)
>  {
> -       struct nouveau_device_priv *nvdev = nouveau_device(dev);
>         struct nouveau_bo_priv *nvbo = calloc(1, sizeof(*nvbo));
>         struct nouveau_bo *bo = &nvbo->base;
>         int ret;
> @@ -397,10 +394,6 @@ nouveau_bo_new(struct nouveau_device *dev, uint32_t flags, uint32_t align,
>                 return ret;
>         }
>
> -       pthread_mutex_lock(&nvdev->lock);
> -       DRMLISTADD(&nvbo->head, &nvdev->bo_list);
> -       pthread_mutex_unlock(&nvdev->lock);
> -
>         *pbo = bo;
>         return 0;
>  }
> @@ -457,6 +450,18 @@ nouveau_bo_wrap_locked(struct nouveau_device *dev, uint32_t handle,
>         return -ENOMEM;
>  }
>
> +static void
> +nouveau_bo_make_global(struct nouveau_bo_priv *nvbo)
> +{
> +       if (!nvbo->head.next) {
> +               struct nouveau_device_priv *nvdev = nouveau_device(nvbo->base.device);
> +               pthread_mutex_lock(&nvdev->lock);
> +               if (!nvbo->head.next)
Something looks a bit strange here. The list is modified under a lock,
so there should be no need for the second if above. Did you have
something else in mind ?

-Emil