On Fri, Dec 8, 2023 at 9:56 AM David Ahern dsahern@kernel.org wrote:
On 12/7/23 5:52 PM, Mina Almasry wrote:
diff --git a/net/core/dev.c b/net/core/dev.c index b8c8be5a912e..30667e4c3b95 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -2120,6 +2120,41 @@ static int netdev_restart_rx_queue(struct net_device *dev, int rxq_idx) return err; }
+struct page_pool_iov *netdev_alloc_dmabuf(struct netdev_dmabuf_binding *binding) +{
struct dmabuf_genpool_chunk_owner *owner;struct page_pool_iov *ppiov;unsigned long dma_addr;ssize_t offset;ssize_t index;dma_addr = gen_pool_alloc_owner(binding->chunk_pool, PAGE_SIZE,Any reason not to allow allocation sizes other than PAGE_SIZE? e.g., 2048 for smaller MTUs or 8192 for larger ones. It can be a property of page_pool and constant across allocations vs allowing different size for each allocation.
Only for simplicity. Supporting non-PAGE_SIZE is certainly possible, but in my estimation it's a huge can of worms worthy of itss own series. I find this series complicated to implement and review and support as-is, and if reasonable I would like to punt that as a future improvement.
At the minimum, I think the needed changes are:
1. The memory provider needs to report to the page pool the alloc size. 2. The page_pool needs to handle non-PAGE_SIZE memory regions. 3. The drivers need to handle non-PAGE_SIZE memory regions. Drivers today handle fragged pages, but that is different because it's a PAGE_SIZE region that is fragged. This is a non-PAGE_SIZE region in the first place. 4. Any PAGE_SIZE assumptions in the entire net stack need to be removed.
At Google we mostly use page aligned MTUs so we're likely not that interested in sub PAGE_SIZE allocations, but we are interested in n * PAGE_SIZE allocations, but, I hope, in a separate followup effort.