While the system heap can return non-contiguous pages, try to allocate larger order pages if possible.
This will allow slight performance gains and make implementing page pooling easier.
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: Daniel Mentz danielmentz@google.com Cc: Chris Goldsworthy cgoldswo@codeaurora.org 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 Reviewed-by: Brian Starkey brian.starkey@arm.com Signed-off-by: John Stultz john.stultz@linaro.org --- v3: * Use page_size() rather then opencoding it v5: * Add comment explaining order size rational --- drivers/dma-buf/heaps/system_heap.c | 89 +++++++++++++++++++++++------ 1 file changed, 71 insertions(+), 18 deletions(-)
diff --git a/drivers/dma-buf/heaps/system_heap.c b/drivers/dma-buf/heaps/system_heap.c index 32b17a5c8079..17e0e9a68baf 100644 --- a/drivers/dma-buf/heaps/system_heap.c +++ b/drivers/dma-buf/heaps/system_heap.c @@ -40,6 +40,20 @@ struct dma_heap_attachment { bool mapped; };
+#define HIGH_ORDER_GFP (((GFP_HIGHUSER | __GFP_ZERO | __GFP_NOWARN \ + | __GFP_NORETRY) & ~__GFP_RECLAIM) \ + | __GFP_COMP) +#define LOW_ORDER_GFP (GFP_HIGHUSER | __GFP_ZERO | __GFP_COMP) +static gfp_t order_flags[] = {HIGH_ORDER_GFP, LOW_ORDER_GFP, LOW_ORDER_GFP}; +/* + * The selection of the orders used for allocation (1MB, 64K, 4K) is designed + * to match with the sizes often found in IOMMUs. Using order 4 pages instead + * of order 0 pages can significantly improve the performance of many IOMMUs + * by reducing TLB pressure and time spent updating page tables. + */ +static const unsigned int orders[] = {8, 4, 0}; +#define NUM_ORDERS ARRAY_SIZE(orders) + static struct sg_table *dup_sg_table(struct sg_table *table) { struct sg_table *new_table; @@ -275,8 +289,11 @@ static void system_heap_dma_buf_release(struct dma_buf *dmabuf) int i;
table = &buffer->sg_table; - for_each_sgtable_sg(table, sg, i) - __free_page(sg_page(sg)); + for_each_sg(table->sgl, sg, table->nents, i) { + struct page *page = sg_page(sg); + + __free_pages(page, compound_order(page)); + } sg_free_table(table); kfree(buffer); } @@ -294,6 +311,26 @@ static const struct dma_buf_ops system_heap_buf_ops = { .release = system_heap_dma_buf_release, };
+static struct page *alloc_largest_available(unsigned long size, + unsigned int max_order) +{ + struct page *page; + int i; + + for (i = 0; i < NUM_ORDERS; i++) { + if (size < (PAGE_SIZE << orders[i])) + continue; + if (max_order < orders[i]) + continue; + + page = alloc_pages(order_flags[i], orders[i]); + if (!page) + continue; + return page; + } + return NULL; +} + static int system_heap_allocate(struct dma_heap *heap, unsigned long len, unsigned long fd_flags, @@ -301,11 +338,13 @@ static int system_heap_allocate(struct dma_heap *heap, { struct system_heap_buffer *buffer; DEFINE_DMA_BUF_EXPORT_INFO(exp_info); + unsigned long size_remaining = len; + unsigned int max_order = orders[0]; struct dma_buf *dmabuf; struct sg_table *table; struct scatterlist *sg; - pgoff_t pagecount; - pgoff_t pg; + struct list_head pages; + struct page *page, *tmp_page; int i, ret = -ENOMEM;
buffer = kzalloc(sizeof(*buffer), GFP_KERNEL); @@ -317,25 +356,35 @@ static int system_heap_allocate(struct dma_heap *heap, buffer->heap = heap; buffer->len = len;
- table = &buffer->sg_table; - pagecount = len / PAGE_SIZE; - if (sg_alloc_table(table, pagecount, GFP_KERNEL)) - goto free_buffer; - - sg = table->sgl; - for (pg = 0; pg < pagecount; pg++) { - struct page *page; + INIT_LIST_HEAD(&pages); + i = 0; + while (size_remaining > 0) { /* * Avoid trying to allocate memory if the process * has been killed by SIGKILL */ if (fatal_signal_pending(current)) - goto free_pages; - page = alloc_page(GFP_KERNEL | __GFP_ZERO); + goto free_buffer; + + page = alloc_largest_available(size_remaining, max_order); if (!page) - goto free_pages; + goto free_buffer; + + list_add_tail(&page->lru, &pages); + size_remaining -= page_size(page); + max_order = compound_order(page); + i++; + } + + table = &buffer->sg_table; + if (sg_alloc_table(table, i, GFP_KERNEL)) + goto free_buffer; + + sg = table->sgl; + list_for_each_entry_safe(page, tmp_page, &pages, lru) { sg_set_page(sg, page, page_size(page), 0); sg = sg_next(sg); + list_del(&page->lru); }
/* create the dmabuf */ @@ -355,14 +404,18 @@ static int system_heap_allocate(struct dma_heap *heap, /* just return, as put will call release and that will free */ return ret; } - return ret;
free_pages: - for_each_sgtable_sg(table, sg, i) - __free_page(sg_page(sg)); + for_each_sgtable_sg(table, sg, i) { + struct page *p = sg_page(sg); + + __free_pages(p, compound_order(p)); + } sg_free_table(table); free_buffer: + list_for_each_entry_safe(page, tmp_page, &pages, lru) + __free_pages(page, compound_order(page)); kfree(buffer);
return ret;