On Thu, Oct 1, 2020 at 7:49 AM Chris Goldsworthy
<cgoldswo@xxxxxxxxxxxxxx> wrote:
> On 2020-09-29 21:46, Chris Goldsworthy 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@xxxxxxxxxx>
> >> Cc: Liam Mark <lmark@xxxxxxxxxxxxxx>
> >> Cc: Laura Abbott <labbott@xxxxxxxxxx>
> >> Cc: Brian Starkey <Brian.Starkey@xxxxxxx>
> >> Cc: Hridya Valsaraju <hridya@xxxxxxxxxx>
> >> Cc: Suren Baghdasaryan <surenb@xxxxxxxxxx>
> >> Cc: Sandeep Patil <sspatil@xxxxxxxxxx>
> >> Cc: Ørjan Eide <orjan.eide@xxxxxxx>
> >> Cc: Robin Murphy <robin.murphy@xxxxxxx>
> >> Cc: Ezequiel Garcia <ezequiel@xxxxxxxxxxxxx>
> >> Cc: Simon Ser <contact@xxxxxxxxxxx>
> >> Cc: James Jones <jajones@xxxxxxxxxx>
> >> Cc: linux-media@xxxxxxxxxxxxxxx
> >> Cc: dri-devel@xxxxxxxxxxxxxxxxxxxxx
> >> Signed-off-by: John Stultz <john.stultz@xxxxxxxxxx>
> >> ---
> >> 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 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 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;
>
> Hey John,
>
> Correct me if I'm wrong, but I think that in order for pp.dma_dir to be
> used in either page_pool_alloc_pages() or page_pool_put_full_page(), we
> need to at least have PP_FLAG_DMA_MAP set (to have
> page_pool_dma_sync_for_device() called, PP_FLAG_DMA_SYNC_DEV should also
> be set I think). I think you'd also need to to have pp->dev set. Are
> we setting dma_dir with the intention of doing the necessary CMOs before
> we start using the page?
Looking, I think my setting of the dma_dir there on the pool is
unnecessary (and as you point out, it doesn't have much effect as long
as the PP_FLAG_DMA_MAP isn't set).
I'm really only using the pagepool as a page cache, and the dmabuf ops
are still used for mapping and syncing operations.
thanks
-john
