| Message ID | 20201124153845.132207-5-ribalda@chromium.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [1/6] dma-mapping: remove the {alloc,free}_noncoherent methods | expand |
On 2020-11-24 15:38, Ricardo Ribalda wrote: > On architectures where the is no coherent caching such as ARM use the > dma_alloc_noncontiguos API and handle manually the cache flushing using > dma_sync_single(). > > With this patch on the affected architectures we can measure up to 20x > performance improvement in uvc_video_copy_data_work(). > > Signed-off-by: Ricardo Ribalda <ribalda@chromium.org> > --- > drivers/media/usb/uvc/uvc_video.c | 74 ++++++++++++++++++++++++++----- > drivers/media/usb/uvc/uvcvideo.h | 1 + > 2 files changed, 63 insertions(+), 12 deletions(-) > > diff --git a/drivers/media/usb/uvc/uvc_video.c b/drivers/media/usb/uvc/uvc_video.c > index a6a441d92b94..9e90b261428a 100644 > --- a/drivers/media/usb/uvc/uvc_video.c > +++ b/drivers/media/usb/uvc/uvc_video.c > @@ -1490,6 +1490,11 @@ static void uvc_video_encode_bulk(struct uvc_urb *uvc_urb, > urb->transfer_buffer_length = stream->urb_size - len; > } > > +static inline struct device *stream_to_dmadev(struct uvc_streaming *stream) > +{ > + return stream->dev->udev->bus->controller->parent; > +} > + > static void uvc_video_complete(struct urb *urb) > { > struct uvc_urb *uvc_urb = urb->context; > @@ -1539,6 +1544,11 @@ 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. > */ > + if (uvc_urb->pages) > + dma_sync_single_for_cpu(stream_to_dmadev(stream), > + urb->transfer_dma, > + urb->transfer_buffer_length, > + DMA_FROM_DEVICE); This doesn't work. Even in iommu-dma, the streaming API still expects to work on physically-contiguous memory that could have been passed to dma_map_single() in the first place. As-is, this will invalidate transfer_buffer_length bytes from the start of the *first* physical page, and thus destroy random other data if lines from subsequent unrelated pages are dirty in caches. The only feasible way to do a DMA sync on disjoint pages in a single call is with a scatterlist. Robin. > stream->decode(uvc_urb, buf, buf_meta); > > /* If no async work is needed, resubmit the URB immediately. */ > @@ -1566,8 +1576,15 @@ static void uvc_free_urb_buffers(struct uvc_streaming *stream) > continue; > > #ifndef CONFIG_DMA_NONCOHERENT > - usb_free_coherent(stream->dev->udev, stream->urb_size, > - uvc_urb->buffer, uvc_urb->dma); > + if (uvc_urb->pages) { > + vunmap(uvc_urb->buffer); > + dma_free_noncontiguous(stream_to_dmadev(stream), > + stream->urb_size, > + uvc_urb->pages, uvc_urb->dma); > + } else { > + usb_free_coherent(stream->dev->udev, stream->urb_size, > + uvc_urb->buffer, uvc_urb->dma); > + } > #else > kfree(uvc_urb->buffer); > #endif > @@ -1577,6 +1594,47 @@ static void uvc_free_urb_buffers(struct uvc_streaming *stream) > stream->urb_size = 0; > } > > +#ifndef CONFIG_DMA_NONCOHERENT > +static bool uvc_alloc_urb_buffer(struct uvc_streaming *stream, > + struct uvc_urb *uvc_urb, gfp_t gfp_flags) > +{ > + struct device *dma_dev = dma_dev = stream_to_dmadev(stream); > + > + if (!dma_can_alloc_noncontiguous(dma_dev)) { > + uvc_urb->buffer = usb_alloc_coherent(stream->dev->udev, > + stream->urb_size, > + gfp_flags | __GFP_NOWARN, > + &uvc_urb->dma); > + return uvc_urb->buffer != NULL; > + } > + > + uvc_urb->pages = dma_alloc_noncontiguous(dma_dev, stream->urb_size, > + &uvc_urb->dma, > + gfp_flags | __GFP_NOWARN, 0); > + if (!uvc_urb->pages) > + return false; > + > + uvc_urb->buffer = vmap(uvc_urb->pages, > + PAGE_ALIGN(stream->urb_size) >> PAGE_SHIFT, > + VM_DMA_COHERENT, PAGE_KERNEL); > + if (!uvc_urb->buffer) { > + dma_free_noncontiguous(dma_dev, stream->urb_size, > + uvc_urb->pages, uvc_urb->dma); > + return false; > + } > + > + return true; > +} > +#else > +static bool uvc_alloc_urb_buffer(struct uvc_streaming *stream, > + struct uvc_urb *uvc_urb, gfp_t gfp_flags) > +{ > + uvc_urb->buffer = kmalloc(stream->urb_size, gfp_flags | __GFP_NOWARN); > + > + return uvc_urb->buffer != NULL; > +} > +#endif > + > /* > * Allocate transfer buffers. This function can be called with buffers > * already allocated when resuming from suspend, in which case it will > @@ -1607,19 +1665,11 @@ static int uvc_alloc_urb_buffers(struct uvc_streaming *stream, > > /* Retry allocations until one succeed. */ > for (; npackets > 1; npackets /= 2) { > + stream->urb_size = psize * npackets; > for (i = 0; i < UVC_URBS; ++i) { > struct uvc_urb *uvc_urb = &stream->uvc_urb[i]; > > - stream->urb_size = psize * npackets; > -#ifndef CONFIG_DMA_NONCOHERENT > - uvc_urb->buffer = usb_alloc_coherent( > - stream->dev->udev, stream->urb_size, > - gfp_flags | __GFP_NOWARN, &uvc_urb->dma); > -#else > - uvc_urb->buffer = > - kmalloc(stream->urb_size, gfp_flags | __GFP_NOWARN); > -#endif > - if (!uvc_urb->buffer) { > + if (!uvc_alloc_urb_buffer(stream, uvc_urb, gfp_flags)) { > uvc_free_urb_buffers(stream); > break; > } > diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h > index a3dfacf069c4..3e3ef1f1daa5 100644 > --- a/drivers/media/usb/uvc/uvcvideo.h > +++ b/drivers/media/usb/uvc/uvcvideo.h > @@ -532,6 +532,7 @@ struct uvc_urb { > > char *buffer; > dma_addr_t dma; > + struct page **pages; > > unsigned int async_operations; > struct uvc_copy_op copy_operations[UVC_MAX_PACKETS]; >
Hi Robin On Tue, Nov 24, 2020 at 5:29 PM Robin Murphy <robin.murphy@arm.com> wrote: > > On 2020-11-24 15:38, Ricardo Ribalda wrote: > > On architectures where the is no coherent caching such as ARM use the > > dma_alloc_noncontiguos API and handle manually the cache flushing using > > dma_sync_single(). > > > > With this patch on the affected architectures we can measure up to 20x > > performance improvement in uvc_video_copy_data_work(). > > > > Signed-off-by: Ricardo Ribalda <ribalda@chromium.org> > > --- > > drivers/media/usb/uvc/uvc_video.c | 74 ++++++++++++++++++++++++++----- > > drivers/media/usb/uvc/uvcvideo.h | 1 + > > 2 files changed, 63 insertions(+), 12 deletions(-) > > > > diff --git a/drivers/media/usb/uvc/uvc_video.c b/drivers/media/usb/uvc/uvc_video.c > > index a6a441d92b94..9e90b261428a 100644 > > --- a/drivers/media/usb/uvc/uvc_video.c > > +++ b/drivers/media/usb/uvc/uvc_video.c > > @@ -1490,6 +1490,11 @@ static void uvc_video_encode_bulk(struct uvc_urb *uvc_urb, > > urb->transfer_buffer_length = stream->urb_size - len; > > } > > > > +static inline struct device *stream_to_dmadev(struct uvc_streaming *stream) > > +{ > > + return stream->dev->udev->bus->controller->parent; > > +} > > + > > static void uvc_video_complete(struct urb *urb) > > { > > struct uvc_urb *uvc_urb = urb->context; > > @@ -1539,6 +1544,11 @@ 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. > > */ > > + if (uvc_urb->pages) > > + dma_sync_single_for_cpu(stream_to_dmadev(stream), > > + urb->transfer_dma, > > + urb->transfer_buffer_length, > > + DMA_FROM_DEVICE); > > This doesn't work. Even in iommu-dma, the streaming API still expects to > work on physically-contiguous memory that could have been passed to > dma_map_single() in the first place. As-is, this will invalidate > transfer_buffer_length bytes from the start of the *first* physical > page, and thus destroy random other data if lines from subsequent > unrelated pages are dirty in caches. > > The only feasible way to do a DMA sync on disjoint pages in a single > call is with a scatterlist. Thanks for pointing this out. I guess I was lucky on my hardware and the areas were always contiguous. Will rework and send back to the list. Thanks again. > > Robin. > > > stream->decode(uvc_urb, buf, buf_meta); > > > > /* If no async work is needed, resubmit the URB immediately. */ > > @@ -1566,8 +1576,15 @@ static void uvc_free_urb_buffers(struct uvc_streaming *stream) > > continue; > > > > #ifndef CONFIG_DMA_NONCOHERENT > > - usb_free_coherent(stream->dev->udev, stream->urb_size, > > - uvc_urb->buffer, uvc_urb->dma); > > + if (uvc_urb->pages) { > > + vunmap(uvc_urb->buffer); > > + dma_free_noncontiguous(stream_to_dmadev(stream), > > + stream->urb_size, > > + uvc_urb->pages, uvc_urb->dma); > > + } else { > > + usb_free_coherent(stream->dev->udev, stream->urb_size, > > + uvc_urb->buffer, uvc_urb->dma); > > + } > > #else > > kfree(uvc_urb->buffer); > > #endif > > @@ -1577,6 +1594,47 @@ static void uvc_free_urb_buffers(struct uvc_streaming *stream) > > stream->urb_size = 0; > > } > > > > +#ifndef CONFIG_DMA_NONCOHERENT > > +static bool uvc_alloc_urb_buffer(struct uvc_streaming *stream, > > + struct uvc_urb *uvc_urb, gfp_t gfp_flags) > > +{ > > + struct device *dma_dev = dma_dev = stream_to_dmadev(stream); > > + > > + if (!dma_can_alloc_noncontiguous(dma_dev)) { > > + uvc_urb->buffer = usb_alloc_coherent(stream->dev->udev, > > + stream->urb_size, > > + gfp_flags | __GFP_NOWARN, > > + &uvc_urb->dma); > > + return uvc_urb->buffer != NULL; > > + } > > + > > + uvc_urb->pages = dma_alloc_noncontiguous(dma_dev, stream->urb_size, > > + &uvc_urb->dma, > > + gfp_flags | __GFP_NOWARN, 0); > > + if (!uvc_urb->pages) > > + return false; > > + > > + uvc_urb->buffer = vmap(uvc_urb->pages, > > + PAGE_ALIGN(stream->urb_size) >> PAGE_SHIFT, > > + VM_DMA_COHERENT, PAGE_KERNEL); > > + if (!uvc_urb->buffer) { > > + dma_free_noncontiguous(dma_dev, stream->urb_size, > > + uvc_urb->pages, uvc_urb->dma); > > + return false; > > + } > > + > > + return true; > > +} > > +#else > > +static bool uvc_alloc_urb_buffer(struct uvc_streaming *stream, > > + struct uvc_urb *uvc_urb, gfp_t gfp_flags) > > +{ > > + uvc_urb->buffer = kmalloc(stream->urb_size, gfp_flags | __GFP_NOWARN); > > + > > + return uvc_urb->buffer != NULL; > > +} > > +#endif > > + > > /* > > * Allocate transfer buffers. This function can be called with buffers > > * already allocated when resuming from suspend, in which case it will > > @@ -1607,19 +1665,11 @@ static int uvc_alloc_urb_buffers(struct uvc_streaming *stream, > > > > /* Retry allocations until one succeed. */ > > for (; npackets > 1; npackets /= 2) { > > + stream->urb_size = psize * npackets; > > for (i = 0; i < UVC_URBS; ++i) { > > struct uvc_urb *uvc_urb = &stream->uvc_urb[i]; > > > > - stream->urb_size = psize * npackets; > > -#ifndef CONFIG_DMA_NONCOHERENT > > - uvc_urb->buffer = usb_alloc_coherent( > > - stream->dev->udev, stream->urb_size, > > - gfp_flags | __GFP_NOWARN, &uvc_urb->dma); > > -#else > > - uvc_urb->buffer = > > - kmalloc(stream->urb_size, gfp_flags | __GFP_NOWARN); > > -#endif > > - if (!uvc_urb->buffer) { > > + if (!uvc_alloc_urb_buffer(stream, uvc_urb, gfp_flags)) { > > uvc_free_urb_buffers(stream); > > break; > > } > > diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h > > index a3dfacf069c4..3e3ef1f1daa5 100644 > > --- a/drivers/media/usb/uvc/uvcvideo.h > > +++ b/drivers/media/usb/uvc/uvcvideo.h > > @@ -532,6 +532,7 @@ struct uvc_urb { > > > > char *buffer; > > dma_addr_t dma; > > + struct page **pages; > > > > unsigned int async_operations; > > struct uvc_copy_op copy_operations[UVC_MAX_PACKETS]; > >
diff --git a/drivers/media/usb/uvc/uvc_video.c b/drivers/media/usb/uvc/uvc_video.c index a6a441d92b94..9e90b261428a 100644 --- a/drivers/media/usb/uvc/uvc_video.c +++ b/drivers/media/usb/uvc/uvc_video.c @@ -1490,6 +1490,11 @@ static void uvc_video_encode_bulk(struct uvc_urb *uvc_urb, urb->transfer_buffer_length = stream->urb_size - len; } +static inline struct device *stream_to_dmadev(struct uvc_streaming *stream) +{ + return stream->dev->udev->bus->controller->parent; +} + static void uvc_video_complete(struct urb *urb) { struct uvc_urb *uvc_urb = urb->context; @@ -1539,6 +1544,11 @@ 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. */ + if (uvc_urb->pages) + dma_sync_single_for_cpu(stream_to_dmadev(stream), + urb->transfer_dma, + urb->transfer_buffer_length, + DMA_FROM_DEVICE); stream->decode(uvc_urb, buf, buf_meta); /* If no async work is needed, resubmit the URB immediately. */ @@ -1566,8 +1576,15 @@ static void uvc_free_urb_buffers(struct uvc_streaming *stream) continue; #ifndef CONFIG_DMA_NONCOHERENT - usb_free_coherent(stream->dev->udev, stream->urb_size, - uvc_urb->buffer, uvc_urb->dma); + if (uvc_urb->pages) { + vunmap(uvc_urb->buffer); + dma_free_noncontiguous(stream_to_dmadev(stream), + stream->urb_size, + uvc_urb->pages, uvc_urb->dma); + } else { + usb_free_coherent(stream->dev->udev, stream->urb_size, + uvc_urb->buffer, uvc_urb->dma); + } #else kfree(uvc_urb->buffer); #endif @@ -1577,6 +1594,47 @@ static void uvc_free_urb_buffers(struct uvc_streaming *stream) stream->urb_size = 0; } +#ifndef CONFIG_DMA_NONCOHERENT +static bool uvc_alloc_urb_buffer(struct uvc_streaming *stream, + struct uvc_urb *uvc_urb, gfp_t gfp_flags) +{ + struct device *dma_dev = dma_dev = stream_to_dmadev(stream); + + if (!dma_can_alloc_noncontiguous(dma_dev)) { + uvc_urb->buffer = usb_alloc_coherent(stream->dev->udev, + stream->urb_size, + gfp_flags | __GFP_NOWARN, + &uvc_urb->dma); + return uvc_urb->buffer != NULL; + } + + uvc_urb->pages = dma_alloc_noncontiguous(dma_dev, stream->urb_size, + &uvc_urb->dma, + gfp_flags | __GFP_NOWARN, 0); + if (!uvc_urb->pages) + return false; + + uvc_urb->buffer = vmap(uvc_urb->pages, + PAGE_ALIGN(stream->urb_size) >> PAGE_SHIFT, + VM_DMA_COHERENT, PAGE_KERNEL); + if (!uvc_urb->buffer) { + dma_free_noncontiguous(dma_dev, stream->urb_size, + uvc_urb->pages, uvc_urb->dma); + return false; + } + + return true; +} +#else +static bool uvc_alloc_urb_buffer(struct uvc_streaming *stream, + struct uvc_urb *uvc_urb, gfp_t gfp_flags) +{ + uvc_urb->buffer = kmalloc(stream->urb_size, gfp_flags | __GFP_NOWARN); + + return uvc_urb->buffer != NULL; +} +#endif + /* * Allocate transfer buffers. This function can be called with buffers * already allocated when resuming from suspend, in which case it will @@ -1607,19 +1665,11 @@ static int uvc_alloc_urb_buffers(struct uvc_streaming *stream, /* Retry allocations until one succeed. */ for (; npackets > 1; npackets /= 2) { + stream->urb_size = psize * npackets; for (i = 0; i < UVC_URBS; ++i) { struct uvc_urb *uvc_urb = &stream->uvc_urb[i]; - stream->urb_size = psize * npackets; -#ifndef CONFIG_DMA_NONCOHERENT - uvc_urb->buffer = usb_alloc_coherent( - stream->dev->udev, stream->urb_size, - gfp_flags | __GFP_NOWARN, &uvc_urb->dma); -#else - uvc_urb->buffer = - kmalloc(stream->urb_size, gfp_flags | __GFP_NOWARN); -#endif - if (!uvc_urb->buffer) { + if (!uvc_alloc_urb_buffer(stream, uvc_urb, gfp_flags)) { uvc_free_urb_buffers(stream); break; } diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h index a3dfacf069c4..3e3ef1f1daa5 100644 --- a/drivers/media/usb/uvc/uvcvideo.h +++ b/drivers/media/usb/uvc/uvcvideo.h @@ -532,6 +532,7 @@ struct uvc_urb { char *buffer; dma_addr_t dma; + struct page **pages; unsigned int async_operations; struct uvc_copy_op copy_operations[UVC_MAX_PACKETS];
On architectures where the is no coherent caching such as ARM use the dma_alloc_noncontiguos API and handle manually the cache flushing using dma_sync_single(). With this patch on the affected architectures we can measure up to 20x performance improvement in uvc_video_copy_data_work(). Signed-off-by: Ricardo Ribalda <ribalda@chromium.org> --- drivers/media/usb/uvc/uvc_video.c | 74 ++++++++++++++++++++++++++----- drivers/media/usb/uvc/uvcvideo.h | 1 + 2 files changed, 63 insertions(+), 12 deletions(-)