On 6/17/2023 12:01 AM, Jakub Kicinski wrote:

On Wed, 14 Jun 2023 10:14:25 -0700 Tony Nguyen wrote:

quoted

+static bool idpf_rx_can_reuse_page(struct idpf_rx_buf *rx_buf)
+{
+	unsigned int last_offset = PAGE_SIZE - rx_buf->buf_size;
+	struct idpf_page_info *pinfo;
+	unsigned int pagecnt_bias;
+	struct page *page;
+
+	pinfo = &rx_buf->page_info[rx_buf->page_indx];
+	pagecnt_bias = pinfo->pagecnt_bias;
+	page = pinfo->page;
+
+	if (unlikely(!dev_page_is_reusable(page)))
+		return false;
+
+	if (PAGE_SIZE < 8192) {
+		/* For 2K buffers, we can reuse the page if we are the
+		 * owner. For 4K buffers, we can reuse the page if there are
+		 * no other others.
+		 */
+		if (unlikely((page_count(page) - pagecnt_bias) >
+			     pinfo->reuse_bias))
+			return false;
+	} else if (pinfo->page_offset > last_offset) {
+		return false;
+	}
+
+	/* If we have drained the page fragment pool we need to update
+	 * the pagecnt_bias and page count so that we fully restock the
+	 * number of references the driver holds.
+	 */
+	if (unlikely(pagecnt_bias == 1)) {
+		page_ref_add(page, USHRT_MAX - 1);
+		pinfo->pagecnt_bias = USHRT_MAX;
+	}
+
+	return true;
+}

If you want to do local recycling you must use the page pool first,
and then share the analysis of how much and why the recycling helps.

We are working on refactoring all the Intel drivers to use the page pool 
API in a unified way and our plan is to update IDPF driver as well, as 
part of that effort.

Thanks,
Pavan