On 4/10/24 02:49, Jakub Kicinski wrote:
On Mon, 08 Apr 2024 11:38:04 +0200 Julien Panis wrote:+static struct sk_buff *am65_cpsw_alloc_skb(struct am65_cpsw_rx_chn *rx_chn, + struct net_device *ndev, + unsigned int len, + int desc_idx, + bool allow_direct) +{ + struct sk_buff *skb; + struct page *page; + + page = page_pool_dev_alloc_pages(rx_chn->page_pool); + if (unlikely(!page)) + return NULL; + + len += AM65_CPSW_HEADROOM; + + skb = build_skb(page_address(page), len);You shouldn't build the skb upfront any more. Give the page to the HW, once HW sends you a completion - build the skbs. If build fails (allocation failure) just give the page back to HW. If it succeeds, however, you'll get a skb which is far more likely to be cache hot.
Not sure I get this point. "Give the page to the HW" = Do you mean that I should dma_map_single() a full page (|PAGE_SIZE|) in am65_cpsw_nuss_rx_push() ?
+ if (unlikely(!skb)) { + page_pool_put_full_page(rx_chn->page_pool, page, allow_direct); + rx_chn->pages[desc_idx] = NULL; + return NULL; + }
