Re: [PATCH v2] media: uvcvideo: use dynamic allocation for uvc_copy_op

[Ricardo Ribalda Delgado]

Hi Kyeongdon

I fail to understand why your approach is faster than the original one.

Is it because of the alignment of struct uvc_copy_op copy_operations ?

Thanks!

On Fri, Sep 3, 2021 at 6:56 AM Kyeongdon Kim <kyeongdon.kim@xxxxxxx> wrote:
>
> There are some issues to handle frame throughput with camera devices
>
> Using devices:
> - Logitech Webcam
> - Intel(R) RealSense(TM) Depth Camera
>
> To improve efficiency, and maximise throughput,
> use dynamic allocation for uvc_copy_op.
>
> Change from struct uvc_copy_op copy_operations[UVC_MAX_PACKETS];
> to struct uvc_copy_op *copy_operations;
>
> Now, only tested bulk video options.
>
> On test device & own debug log to check frame duration(us),
> refer to test result the below:
>
> Use copy_operations[UVC_MAX_PACKETS]
> [UVC] Check time duration(us) : 54732 / 66000
> [UVC] Check time duration(us) : 57452 / 66000
> [UVC] Check time duration(us) : 57413 / 66000
> [UVC] Check time duration(us) : 56713 / 66000
> [UVC] Check time duration(us) : 57967 / 66000
>
> Use *copy_operations
> [UVC] Check time duration(us) : 30804 / 66000
> [UVC] Check time duration(us) : 38642 / 66000
> [UVC] Check time duration(us) : 26011 / 66000
> [UVC] Check time duration(us) : 30116 / 66000
> [UVC] Check time duration(us) : 29265 / 66000
>
> Signed-off-by: Kyeongdon Kim <kyeongdon.kim@xxxxxxx>
> ---
>  drivers/media/usb/uvc/uvc_video.c | 55 ++++++++++++++++++++++++++++++++++++---
>  drivers/media/usb/uvc/uvcvideo.h  |  3 ++-
>  2 files changed, 54 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/media/usb/uvc/uvc_video.c b/drivers/media/usb/uvc/uvc_video.c
> index e164646..3a7c131 100644
> --- a/drivers/media/usb/uvc/uvc_video.c
> +++ b/drivers/media/usb/uvc/uvc_video.c
> @@ -1614,6 +1614,36 @@ static void uvc_video_complete(struct urb *urb)
>         queue_work(stream->async_wq, &uvc_urb->work);
>  }
>
> +static void uvc_free_urb_cop(struct uvc_streaming *stream)
> +{
> +       struct uvc_urb *uvc_urb;
> +
> +       for_each_uvc_urb(uvc_urb, stream) {
> +               if (uvc_urb->copy_operations) {
> +                       kfree(uvc_urb->copy_operations);
> +                       uvc_urb->copy_operations = NULL;
> +               }
> +       }
> +}
> +
> +static int uvc_alloc_urb_cop(struct uvc_streaming *stream, gfp_t gfp_flags)
> +{
> +       int max_packet = stream->urb_max_packets;
> +       struct uvc_urb *uvc_urb;
> +
> +       for_each_uvc_urb(uvc_urb, stream) {
> +               uvc_urb->copy_operations
> +                               = kcalloc(max_packet, sizeof(struct uvc_copy_op), gfp_flags);
> +               if (uvc_urb->copy_operations == NULL)
> +                       goto error;
> +       }
> +       return 0;
> +error:
> +       uvc_free_urb_cop(stream);
> +
> +       return -ENOMEM;
> +}
> +
>  /*
>   * Free transfer buffers.
>   */
> @@ -1687,8 +1717,8 @@ static int uvc_alloc_urb_buffers(struct uvc_streaming *stream,
>          * payloads across multiple URBs.
>          */
>         npackets = DIV_ROUND_UP(size, psize);
> -       if (npackets > UVC_MAX_PACKETS)
> -               npackets = UVC_MAX_PACKETS;
> +       if (npackets > stream->urb_max_packets)
> +               npackets = stream->urb_max_packets;
>
>         /* Retry allocations until one succeed. */
>         for (; npackets > 1; npackets /= 2) {
> @@ -1744,8 +1774,10 @@ static void uvc_video_stop_transfer(struct uvc_streaming *stream,
>                 uvc_urb->urb = NULL;
>         }
>
> -       if (free_buffers)
> +       if (free_buffers) {
>                 uvc_free_urb_buffers(stream);
> +               uvc_free_urb_cop(stream);
> +       }
>  }
>
>  /*
> @@ -1790,10 +1822,18 @@ static int uvc_init_video_isoc(struct uvc_streaming *stream,
>         psize = uvc_endpoint_max_bpi(stream->dev->udev, ep);
>         size = stream->ctrl.dwMaxVideoFrameSize;
>
> +       stream->urb_max_packets = UVC_MAX_PACKETS;
> +
>         npackets = uvc_alloc_urb_buffers(stream, size, psize, gfp_flags);
>         if (npackets == 0)
>                 return -ENOMEM;
>
> +       if (uvc_alloc_urb_cop(stream, gfp_flags) != 0) {
> +               uvc_dbg(stream->dev, VIDEO,
> +                               "Failed to init URBs copy operations.\n");
> +               return -ENOMEM;
> +       }
> +
>         size = npackets * psize;
>
>         for_each_uvc_urb(uvc_urb, stream) {
> @@ -1842,11 +1882,18 @@ static int uvc_init_video_bulk(struct uvc_streaming *stream,
>         psize = usb_endpoint_maxp(&ep->desc);
>         size = stream->ctrl.dwMaxPayloadTransferSize;
>         stream->bulk.max_payload_size = size;
> +       stream->urb_max_packets = DIV_ROUND_UP(size, psize);
>
>         npackets = uvc_alloc_urb_buffers(stream, size, psize, gfp_flags);
>         if (npackets == 0)
>                 return -ENOMEM;
>
> +       if (uvc_alloc_urb_cop(stream, gfp_flags) != 0) {
> +               uvc_dbg(stream->dev, VIDEO,
> +                               "Failed to init URBs copy operations.\n");
> +               return -ENOMEM;
> +       }
> +
>         size = npackets * psize;
>
>         if (usb_endpoint_dir_in(&ep->desc))
> @@ -2147,6 +2194,8 @@ int uvc_video_init(struct uvc_streaming *stream)
>                 }
>         }
>
> +       stream->urb_max_packets = UVC_MAX_PACKETS;
> +
>         /* Prepare asynchronous work items. */
>         for_each_uvc_urb(uvc_urb, stream)
>                 INIT_WORK(&uvc_urb->work, uvc_video_copy_data_work);
> diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h
> index cce5e38..00cf6c9 100644
> --- a/drivers/media/usb/uvc/uvcvideo.h
> +++ b/drivers/media/usb/uvc/uvcvideo.h
> @@ -561,7 +561,7 @@ struct uvc_urb {
>         struct sg_table *sgt;
>
>         unsigned int async_operations;
> -       struct uvc_copy_op copy_operations[UVC_MAX_PACKETS];
> +       struct uvc_copy_op *copy_operations;
>         struct work_struct work;
>  };
>
> @@ -616,6 +616,7 @@ struct uvc_streaming {
>
>         struct uvc_urb uvc_urb[UVC_URBS];
>         unsigned int urb_size;
> +       unsigned int urb_max_packets;
>
>         u32 sequence;
>         u8 last_fid;
> --
> 2.10.2
>


-- 
Ricardo Ribalda