From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mail-lb0-f181.google.com ([209.85.217.181]:34722 "EHLO mail-lb0-f181.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753674Ab3HBOUJ (ORCPT ); Fri, 2 Aug 2013 10:20:09 -0400 Received: by mail-lb0-f181.google.com with SMTP id o10so494746lbi.12 for ; Fri, 02 Aug 2013 07:20:08 -0700 (PDT) From: Ricardo Ribalda Delgado To: Jonathan Corbet , Mauro Carvalho Chehab , Pawel Osciak , Marek Szyprowski , Kyungmin Park , Ismael Luceno , Greg Kroah-Hartman , linux-media@vger.kernel.org, Sylwester Nawrocki Cc: Ricardo Ribalda Delgado Subject: [PATCH v4 1/2] videobuf2-dma-sg: Allocate pages as contiguous as possible Date: Fri, 2 Aug 2013 16:19:59 +0200 Message-Id: <1375453200-28459-2-git-send-email-ricardo.ribalda@gmail.com> In-Reply-To: <1375453200-28459-1-git-send-email-ricardo.ribalda@gmail.com> References: <1375453200-28459-1-git-send-email-ricardo.ribalda@gmail.com> Sender: linux-media-owner@vger.kernel.org List-ID: Most DMA engines have limitations regarding the number of DMA segments (sg-buffers) that they can handle. Videobuffers can easily spread through hundreds of pages. In the previous aproach, the pages were allocated individually, this could led to the creation houndreds of dma segments (sg-buffers) that could not be handled by some DMA engines. This patch tries to minimize the number of DMA segments by using alloc_pages. In the worst case it will behave as before, but most of the times it will reduce the number of dma segments Acked-by: Marek Szyprowski Reviewed-by: Andre Heider Signed-off-by: Ricardo Ribalda Delgado --- drivers/media/v4l2-core/videobuf2-dma-sg.c | 60 +++++++++++++++++++++++----- 1 file changed, 49 insertions(+), 11 deletions(-) diff --git a/drivers/media/v4l2-core/videobuf2-dma-sg.c b/drivers/media/v4l2-core/videobuf2-dma-sg.c index 16ae3dc..4999c48 100644 --- a/drivers/media/v4l2-core/videobuf2-dma-sg.c +++ b/drivers/media/v4l2-core/videobuf2-dma-sg.c @@ -42,10 +42,55 @@ struct vb2_dma_sg_buf { static void vb2_dma_sg_put(void *buf_priv); +static int vb2_dma_sg_alloc_compacted(struct vb2_dma_sg_buf *buf, + gfp_t gfp_flags) +{ + unsigned int last_page = 0; + int size = buf->sg_desc.size; + + while (size > 0) { + struct page *pages; + int order; + int i; + + order = get_order(size); + /* Dont over allocate*/ + if ((PAGE_SIZE << order) > size) + order--; + + pages = NULL; + while (!pages) { + pages = alloc_pages(GFP_KERNEL | __GFP_ZERO | + __GFP_NOWARN | gfp_flags, order); + if (pages) + break; + + if (order == 0) { + while (last_page--) + __free_page(buf->pages[last_page]); + return -ENOMEM; + } + order--; + } + + split_page(pages, order); + for (i = 0; i < (1 << order); i++) { + buf->pages[last_page] = &pages[i]; + sg_set_page(&buf->sg_desc.sglist[last_page], + buf->pages[last_page], PAGE_SIZE, 0); + last_page++; + } + + size -= PAGE_SIZE << order; + } + + return 0; +} + static void *vb2_dma_sg_alloc(void *alloc_ctx, unsigned long size, gfp_t gfp_flags) { struct vb2_dma_sg_buf *buf; - int i; + int ret; buf = kzalloc(sizeof *buf, GFP_KERNEL); if (!buf) @@ -69,14 +114,9 @@ static void *vb2_dma_sg_alloc(void *alloc_ctx, unsigned long size, gfp_t gfp_fla if (!buf->pages) goto fail_pages_array_alloc; - for (i = 0; i < buf->sg_desc.num_pages; ++i) { - buf->pages[i] = alloc_page(GFP_KERNEL | __GFP_ZERO | - __GFP_NOWARN | gfp_flags); - if (NULL == buf->pages[i]) - goto fail_pages_alloc; - sg_set_page(&buf->sg_desc.sglist[i], - buf->pages[i], PAGE_SIZE, 0); - } + ret = vb2_dma_sg_alloc_compacted(buf, gfp_flags); + if (ret) + goto fail_pages_alloc; buf->handler.refcount = &buf->refcount; buf->handler.put = vb2_dma_sg_put; @@ -89,8 +129,6 @@ static void *vb2_dma_sg_alloc(void *alloc_ctx, unsigned long size, gfp_t gfp_fla return buf; fail_pages_alloc: - while (--i >= 0) - __free_page(buf->pages[i]); kfree(buf->pages); fail_pages_array_alloc: -- 1.7.10.4