Re: [PATCH v2 6/6] media: uvcvideo: Use dma_alloc_noncontiguous API
Hi Laurent
Thanks a lot for the review
On Fri, Mar 12, 2021 at 10:19 PM Laurent Pinchart
wrote:
>
> Hi Ricardo,
>
> Thank you for the patch.
>
> On Fri, Mar 12, 2021 at 01:57:09PM +0100, Ricardo Ribalda wrote:
> > On architectures where there is no coherent caching such as ARM use the
> > dma_alloc_noncontiguous API and handle manually the cache flushing using
> > dma_sync_sgtable().
>
> You're actually switching to dma_alloc_noncontiguous() unconditionally,
> not only on those architectures :-) Do I assume correctly that
> dma_alloc_noncontiguous() will do the right thing on x86 too ?
Yes dma_alloc_noncontiguous does all the magic. It falls back to
alloc_dma_pages. Christoph has done a great job.
I tried it in my notebook and although the images are nothing but
pretty it is not the APIs fault. It is because the barbers are closed
due to the pandemic ;).
>
> > With this patch on the affected architectures we can measure up to 20x
> > performance improvement in uvc_video_copy_data_work().
>
> Have you measured performances on x86 to ensure there's no regression ?
Yes in the early stages. I am adding the latest x86 measurements in
the commit message in v3 to make it more clear.
>
> > Eg: aarch64 with an external usb camera
> >
> > NON_CONTIGUOUS
> > frames: 999
> > packets: 999
> > empty: 0 (0 %)
> > errors: 0
> > invalid: 0
> > pts: 0 early, 0 initial, 999 ok
> > scr: 0 count ok, 0 diff ok
> > sof: 2048 <= sof <= 0, freq 0.000 kHz
> > bytes 67034480 : duration 33303
> > FPS: 29.99
> > URB: 523446/4993 uS/qty: 104.836 avg 132.532 std 13.230 min 831.094 max (uS)
> > header: 76564/4993 uS/qty: 15.334 avg 15.229 std 3.438 min 186.875 max (uS)
> > latency: 468945/4992 uS/qty: 93.939 avg 132.577 std 9.531 min 824.010 max
> > (uS)
> > decode: 54161/4993 uS/qty: 10.847 avg 6.313 std 1.614 min 111.458 max (uS)
> > raw decode speed: 9.931 Gbits/s
> > raw URB handling speed: 1.025 Gbits/s
> > throughput: 16.102 Mbits/s
> > URB decode CPU usage 0.162600 %
> >
> > COHERENT
> > frames: 999
> > packets: 999
> > empty: 0 (0 %)
> > errors: 0
> > invalid: 0
> > pts: 0 early, 0 initial, 999 ok
> > scr: 0 count ok, 0 diff ok
> > sof: 2048 <= sof <= 0, freq 0.000 kHz
> > bytes 54683536 : duration 33302
> > FPS: 29.99
> > URB: 1478135/4000 uS/qty: 369.533 avg 390.357 std 22.968 min 3337.865 max
> > (uS)
> > header: 79761/4000 uS/qty: 19.940 avg 18.495 std 1.875 min 336.719 max (uS)
> > latency: 281077/4000 uS/qty: 70.269 avg 83.102 std 5.104 min 735.000 max
> > (uS)
> > decode: 1197057/4000 uS/qty: 299.264 avg 318.080 std 1.615 min 2806.667 max
> > (uS)
> > raw decode speed: 365.470 Mbits/s
> > raw URB handling speed: 295.986 Mbits/s
> > throughput: 13.136 Mbits/s
> > URB decode CPU usage 3.594500 %
> >
> > Signed-off-by: Ricardo Ribalda
> > Reviewed-by: Tomasz Figa
> > Signed-off-by: Christoph Hellwig
> > ---
> >
> > Changelog from v2: (Thanks Laurent)
> >
> > - Fix typos
> > - Use the right dma direction if not capturing
> > - Clear sgt during free
> >
> > drivers/media/usb/uvc/uvc_video.c | 92 +++
> > drivers/media/usb/uvc/uvcvideo.h | 5 +-
> > 2 files changed, 74 insertions(+), 23 deletions(-)
> >
> > diff --git a/drivers/media/usb/uvc/uvc_video.c
> > b/drivers/media/usb/uvc/uvc_video.c
> > index f2f565281e63..8e60f81e2257 100644
> > --- a/drivers/media/usb/uvc/uvc_video.c
> > +++ b/drivers/media/usb/uvc/uvc_video.c
> > @@ -6,11 +6,14 @@
> > * Laurent Pinchart (laurent.pinch...@ideasonboard.com)
> > */
> >
> > +#include
> > +#include
> > #include
> > #include
> > #include
> > #include
> > #include
> > +#include
> > #include
> > #include
> > #include
> > @@ -1096,6 +1099,34 @@ static int uvc_video_decode_start(struct
> > uvc_streaming *stream,
> > return data[0];
> > }
> >
> > +static inline enum dma_data_direction stream_dir(struct uvc_streaming
> > *stream)
> > +{
> > + if (stream->type == V4L2_BUF_TYPE_VIDEO_CAPTURE)
> > + return DMA_FROM_DEVICE;
> > + else
> > + return DMA_TO_DEVICE;
> > +}
> > +
> > +static inline struct device *stream_to_dmadev(struct uvc_streaming *stream)
> > +{
> > + return bus_to_hcd(stream->dev->udev->bus)->self.sysdev;
> > +}
> > +
> > +static void uvc_urb_dma_sync(struct uvc_urb *uvc_urb, bool for_device)
>
> Maybe nitpicking a little bit, but wouldn't the code be clearer if you
> created uvc_urb_dma_sync_for_cpu() and uvc_urb_dma_sync_for_device() ?
> When reading
>
> uvc_urb_dma_sync(uvc_urb, true);
>
> I have to constantly look up the definition of the function to figure
> out what boolean value corresponds to what direction.
>
> Given that uvc_urb_dma_sync(..., true) is always called right before
> submitting the URB, we could even create a uvc_submit_urb() function
> that groups the dma_sync_sgtable_for_device() and usb_submit_urb()
> calls, and do without uvc_urb_dma_sync_for_device(). Up to you on this
> one.
I Like it! thanks for the idea
>
>
Re: [PATCH v2 6/6] media: uvcvideo: Use dma_alloc_noncontiguous API
Hi Ricardo,
On Fri, Mar 12, 2021 at 11:15:46PM +0100, Ricardo Ribalda Delgado wrote:
> On Fri, Mar 12, 2021 at 10:19 PM Laurent Pinchart wrote:
> > On Fri, Mar 12, 2021 at 01:57:09PM +0100, Ricardo Ribalda wrote:
> > > On architectures where there is no coherent caching such as ARM use the
> > > dma_alloc_noncontiguous API and handle manually the cache flushing using
> > > dma_sync_sgtable().
> >
> > You're actually switching to dma_alloc_noncontiguous() unconditionally,
> > not only on those architectures :-) Do I assume correctly that
> > dma_alloc_noncontiguous() will do the right thing on x86 too ?
>
> Yes dma_alloc_noncontiguous does all the magic. It falls back to
> alloc_dma_pages. Christoph has done a great job.
It's a really nice work yes.
Maybe the commit message could be reworded accordingly then, to
explain that we switch to dma_alloc_noncontiguous() unconditionally as
it handles the differences behind the scenes ?
> I tried it in my notebook and although the images are nothing but
> pretty it is not the APIs fault. It is because the barbers are closed
> due to the pandemic ;).
:-)
> > > With this patch on the affected architectures we can measure up to 20x
> > > performance improvement in uvc_video_copy_data_work().
> >
> > Have you measured performances on x86 to ensure there's no regression ?
>
> Yes in the early stages. I am adding the latest x86 measurements in
> the commit message in v3 to make it more clear.
>
> > > Eg: aarch64 with an external usb camera
> > >
> > > NON_CONTIGUOUS
> > > frames: 999
> > > packets: 999
> > > empty: 0 (0 %)
> > > errors: 0
> > > invalid: 0
> > > pts: 0 early, 0 initial, 999 ok
> > > scr: 0 count ok, 0 diff ok
> > > sof: 2048 <= sof <= 0, freq 0.000 kHz
> > > bytes 67034480 : duration 33303
> > > FPS: 29.99
> > > URB: 523446/4993 uS/qty: 104.836 avg 132.532 std 13.230 min 831.094 max
> > > (uS)
> > > header: 76564/4993 uS/qty: 15.334 avg 15.229 std 3.438 min 186.875 max
> > > (uS)
> > > latency: 468945/4992 uS/qty: 93.939 avg 132.577 std 9.531 min 824.010 max
> > > (uS)
> > > decode: 54161/4993 uS/qty: 10.847 avg 6.313 std 1.614 min 111.458 max (uS)
> > > raw decode speed: 9.931 Gbits/s
> > > raw URB handling speed: 1.025 Gbits/s
> > > throughput: 16.102 Mbits/s
> > > URB decode CPU usage 0.162600 %
> > >
> > > COHERENT
> > > frames: 999
> > > packets: 999
> > > empty: 0 (0 %)
> > > errors: 0
> > > invalid: 0
> > > pts: 0 early, 0 initial, 999 ok
> > > scr: 0 count ok, 0 diff ok
> > > sof: 2048 <= sof <= 0, freq 0.000 kHz
> > > bytes 54683536 : duration 33302
> > > FPS: 29.99
> > > URB: 1478135/4000 uS/qty: 369.533 avg 390.357 std 22.968 min 3337.865 max
> > > (uS)
> > > header: 79761/4000 uS/qty: 19.940 avg 18.495 std 1.875 min 336.719 max
> > > (uS)
> > > latency: 281077/4000 uS/qty: 70.269 avg 83.102 std 5.104 min 735.000 max
> > > (uS)
> > > decode: 1197057/4000 uS/qty: 299.264 avg 318.080 std 1.615 min 2806.667
> > > max (uS)
> > > raw decode speed: 365.470 Mbits/s
> > > raw URB handling speed: 295.986 Mbits/s
> > > throughput: 13.136 Mbits/s
> > > URB decode CPU usage 3.594500 %
> > >
> > > Signed-off-by: Ricardo Ribalda
> > > Reviewed-by: Tomasz Figa
> > > Signed-off-by: Christoph Hellwig
> > > ---
> > >
> > > Changelog from v2: (Thanks Laurent)
> > >
> > > - Fix typos
> > > - Use the right dma direction if not capturing
> > > - Clear sgt during free
> > >
> > > drivers/media/usb/uvc/uvc_video.c | 92 +++
> > > drivers/media/usb/uvc/uvcvideo.h | 5 +-
> > > 2 files changed, 74 insertions(+), 23 deletions(-)
> > >
> > > diff --git a/drivers/media/usb/uvc/uvc_video.c
> > > b/drivers/media/usb/uvc/uvc_video.c
> > > index f2f565281e63..8e60f81e2257 100644
> > > --- a/drivers/media/usb/uvc/uvc_video.c
> > > +++ b/drivers/media/usb/uvc/uvc_video.c
> > > @@ -6,11 +6,14 @@
> > > * Laurent Pinchart (laurent.pinch...@ideasonboard.com)
> > > */
> > >
> > > +#include
> > > +#include
> > > #include
> > > #include
> > > #include
> > > #include
> > > #include
> > > +#include
> > > #include
> > > #include
> > > #include
> > > @@ -1096,6 +1099,34 @@ static int uvc_video_decode_start(struct
> > > uvc_streaming *stream,
> > > return data[0];
> > > }
> > >
> > > +static inline enum dma_data_direction stream_dir(struct uvc_streaming
> > > *stream)
> > > +{
> > > + if (stream->type == V4L2_BUF_TYPE_VIDEO_CAPTURE)
> > > + return DMA_FROM_DEVICE;
> > > + else
> > > + return DMA_TO_DEVICE;
> > > +}
> > > +
> > > +static inline struct device *stream_to_dmadev(struct uvc_streaming
> > > *stream)
> > > +{
> > > + return bus_to_hcd(stream->dev->udev->bus)->self.sysdev;
> > > +}
> > > +
> > > +static void uvc_urb_dma_sync(struct uvc_urb *uvc_urb, bool for_device)
> >
> > Maybe nitpicking a little bit, but wouldn't the code be clearer if you
> > created uvc_urb_dma_sync_for_cpu() and uvc_urb_dma_sync_for_device() ?
> > When reading
> >
> >
Re: [PATCH v2 6/6] media: uvcvideo: Use dma_alloc_noncontiguous API
Hi Ricardo,
Thank you for the patch.
On Fri, Mar 12, 2021 at 01:57:09PM +0100, Ricardo Ribalda wrote:
> On architectures where there is no coherent caching such as ARM use the
> dma_alloc_noncontiguous API and handle manually the cache flushing using
> dma_sync_sgtable().
You're actually switching to dma_alloc_noncontiguous() unconditionally,
not only on those architectures :-) Do I assume correctly that
dma_alloc_noncontiguous() will do the right thing on x86 too ?
> With this patch on the affected architectures we can measure up to 20x
> performance improvement in uvc_video_copy_data_work().
Have you measured performances on x86 to ensure there's no regression ?
> Eg: aarch64 with an external usb camera
>
> NON_CONTIGUOUS
> frames: 999
> packets: 999
> empty: 0 (0 %)
> errors: 0
> invalid: 0
> pts: 0 early, 0 initial, 999 ok
> scr: 0 count ok, 0 diff ok
> sof: 2048 <= sof <= 0, freq 0.000 kHz
> bytes 67034480 : duration 33303
> FPS: 29.99
> URB: 523446/4993 uS/qty: 104.836 avg 132.532 std 13.230 min 831.094 max (uS)
> header: 76564/4993 uS/qty: 15.334 avg 15.229 std 3.438 min 186.875 max (uS)
> latency: 468945/4992 uS/qty: 93.939 avg 132.577 std 9.531 min 824.010 max (uS)
> decode: 54161/4993 uS/qty: 10.847 avg 6.313 std 1.614 min 111.458 max (uS)
> raw decode speed: 9.931 Gbits/s
> raw URB handling speed: 1.025 Gbits/s
> throughput: 16.102 Mbits/s
> URB decode CPU usage 0.162600 %
>
> COHERENT
> frames: 999
> packets: 999
> empty: 0 (0 %)
> errors: 0
> invalid: 0
> pts: 0 early, 0 initial, 999 ok
> scr: 0 count ok, 0 diff ok
> sof: 2048 <= sof <= 0, freq 0.000 kHz
> bytes 54683536 : duration 33302
> FPS: 29.99
> URB: 1478135/4000 uS/qty: 369.533 avg 390.357 std 22.968 min 3337.865 max (uS)
> header: 79761/4000 uS/qty: 19.940 avg 18.495 std 1.875 min 336.719 max (uS)
> latency: 281077/4000 uS/qty: 70.269 avg 83.102 std 5.104 min 735.000 max (uS)
> decode: 1197057/4000 uS/qty: 299.264 avg 318.080 std 1.615 min 2806.667 max
> (uS)
> raw decode speed: 365.470 Mbits/s
> raw URB handling speed: 295.986 Mbits/s
> throughput: 13.136 Mbits/s
> URB decode CPU usage 3.594500 %
>
> Signed-off-by: Ricardo Ribalda
> Reviewed-by: Tomasz Figa
> Signed-off-by: Christoph Hellwig
> ---
>
> Changelog from v2: (Thanks Laurent)
>
> - Fix typos
> - Use the right dma direction if not capturing
> - Clear sgt during free
>
> drivers/media/usb/uvc/uvc_video.c | 92 +++
> drivers/media/usb/uvc/uvcvideo.h | 5 +-
> 2 files changed, 74 insertions(+), 23 deletions(-)
>
> diff --git a/drivers/media/usb/uvc/uvc_video.c
> b/drivers/media/usb/uvc/uvc_video.c
> index f2f565281e63..8e60f81e2257 100644
> --- a/drivers/media/usb/uvc/uvc_video.c
> +++ b/drivers/media/usb/uvc/uvc_video.c
> @@ -6,11 +6,14 @@
> * Laurent Pinchart (laurent.pinch...@ideasonboard.com)
> */
>
> +#include
> +#include
> #include
> #include
> #include
> #include
> #include
> +#include
> #include
> #include
> #include
> @@ -1096,6 +1099,34 @@ static int uvc_video_decode_start(struct uvc_streaming
> *stream,
> return data[0];
> }
>
> +static inline enum dma_data_direction stream_dir(struct uvc_streaming
> *stream)
> +{
> + if (stream->type == V4L2_BUF_TYPE_VIDEO_CAPTURE)
> + return DMA_FROM_DEVICE;
> + else
> + return DMA_TO_DEVICE;
> +}
> +
> +static inline struct device *stream_to_dmadev(struct uvc_streaming *stream)
> +{
> + return bus_to_hcd(stream->dev->udev->bus)->self.sysdev;
> +}
> +
> +static void uvc_urb_dma_sync(struct uvc_urb *uvc_urb, bool for_device)
Maybe nitpicking a little bit, but wouldn't the code be clearer if you
created uvc_urb_dma_sync_for_cpu() and uvc_urb_dma_sync_for_device() ?
When reading
uvc_urb_dma_sync(uvc_urb, true);
I have to constantly look up the definition of the function to figure
out what boolean value corresponds to what direction.
Given that uvc_urb_dma_sync(..., true) is always called right before
submitting the URB, we could even create a uvc_submit_urb() function
that groups the dma_sync_sgtable_for_device() and usb_submit_urb()
calls, and do without uvc_urb_dma_sync_for_device(). Up to you on this
one.
With those small changes, and assuming there's no performance regression
on x86,
Reviewed-by: Laurent Pinchart
> +{
> + struct device *dma_dev = stream_to_dmadev(uvc_urb->stream);
> +
> + if (for_device) {
> + dma_sync_sgtable_for_device(dma_dev, uvc_urb->sgt,
> + stream_dir(uvc_urb->stream));
> + } else {
> + dma_sync_sgtable_for_cpu(dma_dev, uvc_urb->sgt,
> + stream_dir(uvc_urb->stream));
> + invalidate_kernel_vmap_range(uvc_urb->buffer,
> + uvc_urb->stream->urb_size);
> + }
> +}
> +
> /*
> * uvc_video_decode_data_work: Asynchronous memcpy processing
> *
> @@ -1117,6 +1148,8 @@ static void
[PATCH v2 6/6] media: uvcvideo: Use dma_alloc_noncontiguous API
On architectures where there is no coherent caching such as ARM use the
dma_alloc_noncontiguous API and handle manually the cache flushing using
dma_sync_sgtable().
With this patch on the affected architectures we can measure up to 20x
performance improvement in uvc_video_copy_data_work().
Eg: aarch64 with an external usb camera
NON_CONTIGUOUS
frames: 999
packets: 999
empty: 0 (0 %)
errors: 0
invalid: 0
pts: 0 early, 0 initial, 999 ok
scr: 0 count ok, 0 diff ok
sof: 2048 <= sof <= 0, freq 0.000 kHz
bytes 67034480 : duration 33303
FPS: 29.99
URB: 523446/4993 uS/qty: 104.836 avg 132.532 std 13.230 min 831.094 max (uS)
header: 76564/4993 uS/qty: 15.334 avg 15.229 std 3.438 min 186.875 max (uS)
latency: 468945/4992 uS/qty: 93.939 avg 132.577 std 9.531 min 824.010 max (uS)
decode: 54161/4993 uS/qty: 10.847 avg 6.313 std 1.614 min 111.458 max (uS)
raw decode speed: 9.931 Gbits/s
raw URB handling speed: 1.025 Gbits/s
throughput: 16.102 Mbits/s
URB decode CPU usage 0.162600 %
COHERENT
frames: 999
packets: 999
empty: 0 (0 %)
errors: 0
invalid: 0
pts: 0 early, 0 initial, 999 ok
scr: 0 count ok, 0 diff ok
sof: 2048 <= sof <= 0, freq 0.000 kHz
bytes 54683536 : duration 33302
FPS: 29.99
URB: 1478135/4000 uS/qty: 369.533 avg 390.357 std 22.968 min 3337.865 max (uS)
header: 79761/4000 uS/qty: 19.940 avg 18.495 std 1.875 min 336.719 max (uS)
latency: 281077/4000 uS/qty: 70.269 avg 83.102 std 5.104 min 735.000 max (uS)
decode: 1197057/4000 uS/qty: 299.264 avg 318.080 std 1.615 min 2806.667 max (uS)
raw decode speed: 365.470 Mbits/s
raw URB handling speed: 295.986 Mbits/s
throughput: 13.136 Mbits/s
URB decode CPU usage 3.594500 %
Signed-off-by: Ricardo Ribalda
Reviewed-by: Tomasz Figa
Signed-off-by: Christoph Hellwig
---
Changelog from v2: (Thanks Laurent)
- Fix typos
- Use the right dma direction if not capturing
- Clear sgt during free
drivers/media/usb/uvc/uvc_video.c | 92 +++
drivers/media/usb/uvc/uvcvideo.h | 5 +-
2 files changed, 74 insertions(+), 23 deletions(-)
diff --git a/drivers/media/usb/uvc/uvc_video.c
b/drivers/media/usb/uvc/uvc_video.c
index f2f565281e63..8e60f81e2257 100644
--- a/drivers/media/usb/uvc/uvc_video.c
+++ b/drivers/media/usb/uvc/uvc_video.c
@@ -6,11 +6,14 @@
* Laurent Pinchart (laurent.pinch...@ideasonboard.com)
*/
+#include
+#include
#include
#include
#include
#include
#include
+#include
#include
#include
#include
@@ -1096,6 +1099,34 @@ static int uvc_video_decode_start(struct uvc_streaming
*stream,
return data[0];
}
+static inline enum dma_data_direction stream_dir(struct uvc_streaming *stream)
+{
+ if (stream->type == V4L2_BUF_TYPE_VIDEO_CAPTURE)
+ return DMA_FROM_DEVICE;
+ else
+ return DMA_TO_DEVICE;
+}
+
+static inline struct device *stream_to_dmadev(struct uvc_streaming *stream)
+{
+ return bus_to_hcd(stream->dev->udev->bus)->self.sysdev;
+}
+
+static void uvc_urb_dma_sync(struct uvc_urb *uvc_urb, bool for_device)
+{
+ struct device *dma_dev = stream_to_dmadev(uvc_urb->stream);
+
+ if (for_device) {
+ dma_sync_sgtable_for_device(dma_dev, uvc_urb->sgt,
+ stream_dir(uvc_urb->stream));
+ } else {
+ dma_sync_sgtable_for_cpu(dma_dev, uvc_urb->sgt,
+stream_dir(uvc_urb->stream));
+ invalidate_kernel_vmap_range(uvc_urb->buffer,
+uvc_urb->stream->urb_size);
+ }
+}
+
/*
* uvc_video_decode_data_work: Asynchronous memcpy processing
*
@@ -1117,6 +1148,8 @@ static void uvc_video_copy_data_work(struct work_struct
*work)
uvc_queue_buffer_release(op->buf);
}
+ uvc_urb_dma_sync(uvc_urb, true);
+
ret = usb_submit_urb(uvc_urb->urb, GFP_KERNEL);
if (ret < 0)
dev_err(_urb->stream->intf->dev,
@@ -1541,10 +1574,12 @@ static void uvc_video_complete(struct urb *urb)
* Process the URB headers, and optionally queue expensive memcpy tasks
* to be deferred to a work queue.
*/
+ uvc_urb_dma_sync(uvc_urb, false);
stream->decode(uvc_urb, buf, buf_meta);
/* If no async work is needed, resubmit the URB immediately. */
if (!uvc_urb->async_operations) {
+ uvc_urb_dma_sync(uvc_urb, true);
ret = usb_submit_urb(uvc_urb->urb, GFP_ATOMIC);
if (ret < 0)
dev_err(>intf->dev,
@@ -1560,24 +1595,49 @@ static void uvc_video_complete(struct urb *urb)
*/
static void uvc_free_urb_buffers(struct uvc_streaming *stream)
{
+ struct device *dma_dev = stream_to_dmadev(stream);
struct uvc_urb *uvc_urb;
for_each_uvc_urb(uvc_urb, stream) {
if (!uvc_urb->buffer)
continue;
-#ifndef CONFIG_DMA_NONCOHERENT
-
