On Tue, Sep 29, 2020 at 9:46 PM Chris Goldsworthy cgoldswo@codeaurora.org wrote:
On 2020-09-25 21:24, 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@linaro.org Cc: Liam Mark lmark@codeaurora.org Cc: Laura Abbott labbott@kernel.org Cc: Brian Starkey Brian.Starkey@arm.com Cc: Hridya Valsaraju hridya@google.com Cc: Suren Baghdasaryan surenb@google.com Cc: Sandeep Patil sspatil@google.com Cc: Ørjan Eide orjan.eide@arm.com Cc: Robin Murphy robin.murphy@arm.com Cc: Ezequiel Garcia ezequiel@collabora.com Cc: Simon Ser contact@emersion.fr Cc: James Jones jajones@nvidia.com Cc: linux-media@vger.kernel.org Cc: dri-devel@lists.freedesktop.org Signed-off-by: John Stultz john.stultz@linaro.org
drivers/dma-buf/heaps/Kconfig | 1 + drivers/dma-buf/heaps/system_heap.c | 32 +++++++++++++++++++++++++---- 2 files changed, 29 insertions(+), 4 deletions(-)
diff --git a/drivers/dma-buf/heaps/Kconfig b/drivers/dma-buf/heaps/Kconfig index a5eef06c4226..f13cde4321b1 100644 --- a/drivers/dma-buf/heaps/Kconfig +++ b/drivers/dma-buf/heaps/Kconfig @@ -1,6 +1,7 @@ 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 systemheap 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 882a632e9bb7..9f57b4c8ae69 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>
struct dma_heap *sys_heap;
@@ -46,6 +47,7 @@ struct dma_heap_attachment { 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) { @@ -264,13 +266,17 @@ 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; 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);@@ -300,8 +306,7 @@ 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;@@ -406,6 +411,25 @@ 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];pp.dma_dir = DMA_BIDIRECTIONAL;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;This is cool, I didn't know about this pooling code under /net/core. Nice and compact.
Oh, bummer. I just realized when allocating w/ __GFP_ZERO from the page-pool, the logic doesn't actually clear pages when pulling from the cache. So unfortunately this is what accounts for much of the performance benefit I was seeing with this approach, so I'll have to retract my claim on the performance gain with this. :(
I've got a first pass at zeroing the pages we put into the pool, but the numbers are not so great just yet so I've got some further work to do.
thanks -john