ionic: implement Rx page reuse

Rework the Rx buffer allocations to use pages twice when using
normal MTU in order to cut down on buffer allocation and mapping
overhead.

Instead of tracking individual pages, in which we may have
wasted half the space when using standard 1500 MTU, we track
buffers which use half pages, so we can use the second half
of the page rather than allocate and map a new page once the
first buffer has been used.

Signed-off-by: Shannon Nelson <snelson@pensando.io>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 9 insertions, 3 deletions

diff --git a/drivers/net/ethernet/pensando/ionic/ionic_dev.h b/drivers/net/ethernet/pensando/ionic/ionic_dev.h
index 690768ff0143..0f877c86eba6 100644
--- a/drivers/net/ethernet/pensando/ionic/ionic_dev.h
+++ b/drivers/net/ethernet/pensando/ionic/ionic_dev.h
@@ -170,9 +170,15 @@ typedef void (*ionic_desc_cb)(struct ionic_queue *q,
 			      struct ionic_desc_info *desc_info,
 			      struct ionic_cq_info *cq_info, void *cb_arg);
 
-struct ionic_page_info {
+#define IONIC_PAGE_SIZE				PAGE_SIZE
+#define IONIC_PAGE_SPLIT_SZ			(PAGE_SIZE / 2)
+#define IONIC_PAGE_GFP_MASK			(GFP_ATOMIC | __GFP_NOWARN |\
+						 __GFP_COMP | __GFP_MEMALLOC)
+
+struct ionic_buf_info {
 	struct page *page;
 	dma_addr_t dma_addr;
+	u32 page_offset;
 };
 
 struct ionic_desc_info {
@@ -187,8 +193,8 @@ struct ionic_desc_info {
 		struct ionic_txq_sg_desc *txq_sg_desc;
 		struct ionic_rxq_sg_desc *rxq_sgl_desc;
 	};
-	unsigned int npages;
-	struct ionic_page_info pages[IONIC_RX_MAX_SG_ELEMS + 1];
+	unsigned int nbufs;
+	struct ionic_buf_info bufs[IONIC_RX_MAX_SG_ELEMS + 1];
 	ionic_desc_cb cb;
 	void *cb_arg;
 };