[RFC][PATCH 2/3] dma-buf: system_heap: Add pagepool support to system heap
Daniel Vetter
daniel at ffwll.ch
Fri Dec 18 14:36:17 UTC 2020
On Thu, Dec 17, 2020 at 11:06:11PM +0000, John Stultz wrote:
> Reuse/abuse the pagepool code from the network code to speed
> up allocation performance.
>
> This is similar to the ION pagepool usage, but tries to
> utilize generic code instead of a custom implementation.
>
> Cc: Sumit Semwal <sumit.semwal at linaro.org>
> Cc: Liam Mark <lmark at codeaurora.org>
> Cc: Chris Goldsworthy <cgoldswo at codeaurora.org>
> Cc: Laura Abbott <labbott at kernel.org>
> Cc: Brian Starkey <Brian.Starkey at arm.com>
> Cc: Hridya Valsaraju <hridya at google.com>
> Cc: Suren Baghdasaryan <surenb at google.com>
> Cc: Sandeep Patil <sspatil at google.com>
> Cc: Daniel Mentz <danielmentz at google.com>
> Cc: Ørjan Eide <orjan.eide at arm.com>
> Cc: Robin Murphy <robin.murphy at arm.com>
> Cc: Ezequiel Garcia <ezequiel at collabora.com>
> Cc: Simon Ser <contact at emersion.fr>
> Cc: James Jones <jajones at nvidia.com>
> Cc: linux-media at vger.kernel.org
> Cc: dri-devel at lists.freedesktop.org
> Signed-off-by: John Stultz <john.stultz at linaro.org>
We also have one of these in ttm. I think we should have at most one of
these for the gpu ecosystem overall, maybe as a helper that can be plugged
into all the places.
Or I'm kinda missing something, which could be since I only glanced at
yours for a bit. But it's also called page pool for buffer allocations,
and I don't think there's that many ways to implement that really :-)
-Daniel
> ---
> drivers/dma-buf/heaps/Kconfig | 1 +
> drivers/dma-buf/heaps/system_heap.c | 68 +++++++++++++++++++++++++++--
> 2 files changed, 65 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/dma-buf/heaps/Kconfig b/drivers/dma-buf/heaps/Kconfig
> index ecf65204f714..fa5e1c330cce 100644
> --- a/drivers/dma-buf/heaps/Kconfig
> +++ b/drivers/dma-buf/heaps/Kconfig
> @@ -4,6 +4,7 @@ config DMABUF_HEAPS_DEFERRED_FREE
> config DMABUF_HEAPS_SYSTEM
> bool "DMA-BUF System Heap"
> depends on DMABUF_HEAPS
> + select PAGE_POOL
> help
> Choose this option to enable the system dmabuf heap. The system heap
> is backed by pages from the buddy allocator. If in doubt, say Y.
> diff --git a/drivers/dma-buf/heaps/system_heap.c b/drivers/dma-buf/heaps/system_heap.c
> index 17e0e9a68baf..885e30894b77 100644
> --- a/drivers/dma-buf/heaps/system_heap.c
> +++ b/drivers/dma-buf/heaps/system_heap.c
> @@ -20,6 +20,7 @@
> #include <linux/scatterlist.h>
> #include <linux/slab.h>
> #include <linux/vmalloc.h>
> +#include <net/page_pool.h>
>
> static struct dma_heap *sys_heap;
>
> @@ -53,6 +54,7 @@ static gfp_t order_flags[] = {HIGH_ORDER_GFP, LOW_ORDER_GFP, LOW_ORDER_GFP};
> */
> static const unsigned int orders[] = {8, 4, 0};
> #define NUM_ORDERS ARRAY_SIZE(orders)
> +struct page_pool *pools[NUM_ORDERS];
>
> static struct sg_table *dup_sg_table(struct sg_table *table)
> {
> @@ -281,18 +283,59 @@ static void system_heap_vunmap(struct dma_buf *dmabuf, struct dma_buf_map *map)
> dma_buf_map_clear(map);
> }
>
> +static int system_heap_clear_pages(struct page **pages, int num, pgprot_t pgprot)
> +{
> + void *addr = vmap(pages, num, VM_MAP, pgprot);
> +
> + if (!addr)
> + return -ENOMEM;
> + memset(addr, 0, PAGE_SIZE * num);
> + vunmap(addr);
> + return 0;
> +}
> +
> +static int system_heap_zero_buffer(struct system_heap_buffer *buffer)
> +{
> + struct sg_table *sgt = &buffer->sg_table;
> + struct sg_page_iter piter;
> + struct page *pages[32];
> + int p = 0;
> + int ret = 0;
> +
> + for_each_sgtable_page(sgt, &piter, 0) {
> + pages[p++] = sg_page_iter_page(&piter);
> + if (p == ARRAY_SIZE(pages)) {
> + ret = system_heap_clear_pages(pages, p, PAGE_KERNEL);
> + if (ret)
> + return ret;
> + p = 0;
> + }
> + }
> + if (p)
> + ret = system_heap_clear_pages(pages, p, PAGE_KERNEL);
> +
> + return ret;
> +}
> +
> static void system_heap_dma_buf_release(struct dma_buf *dmabuf)
> {
> struct system_heap_buffer *buffer = dmabuf->priv;
> struct sg_table *table;
> struct scatterlist *sg;
> - int i;
> + int i, j;
> +
> + /* Zero the buffer pages before adding back to the pool */
> + system_heap_zero_buffer(buffer);
>
> table = &buffer->sg_table;
> for_each_sg(table->sgl, sg, table->nents, i) {
> struct page *page = sg_page(sg);
>
> - __free_pages(page, compound_order(page));
> + for (j = 0; j < NUM_ORDERS; j++) {
> + if (compound_order(page) == orders[j])
> + break;
> + }
> + page_pool_put_full_page(pools[j], page, false);
> }
> sg_free_table(table);
> kfree(buffer);
> @@ -322,8 +365,7 @@ static struct page *alloc_largest_available(unsigned long size,
> continue;
> if (max_order < orders[i])
> continue;
> -
> - page = alloc_pages(order_flags[i], orders[i]);
> + page = page_pool_alloc_pages(pools[i], order_flags[i]);
> if (!page)
> continue;
> return page;
> @@ -428,6 +470,24 @@ static const struct dma_heap_ops system_heap_ops = {
> static int system_heap_create(void)
> {
> struct dma_heap_export_info exp_info;
> + int i;
> +
> + for (i = 0; i < NUM_ORDERS; i++) {
> + struct page_pool_params pp;
> +
> + memset(&pp, 0, sizeof(pp));
> + pp.order = orders[i];
> + pools[i] = page_pool_create(&pp);
> +
> + if (IS_ERR(pools[i])) {
> + int j;
> +
> + pr_err("%s: page pool creation failed!\n", __func__);
> + for (j = 0; j < i; j++)
> + page_pool_destroy(pools[j]);
> + return PTR_ERR(pools[i]);
> + }
> + }
>
> exp_info.name = "system";
> exp_info.ops = &system_heap_ops;
> --
> 2.17.1
>
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--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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