[FROMLIST] net: stmmac: Convert prefetch() to net_prefetch() for rece…

…ived frames

next inclusion
from next-20250122
category: performance

The size of DMA descriptors is 32 bytes at most.
net_prefetch() for received frames, and keep prefetch() for descriptors.

This patch brings ~4.8% driver performance improvement in a TCP RX
throughput test with iPerf tool on a single isolated Cortex-A65 CPU
core, 2.92 Gbits/sec increased to 3.06 Gbits/sec.

Suggested-by: Joe Damato <[email protected]>
Signed-off-by: Furong Xu <[email protected]>
Reviewed-by: Yanteng Si <[email protected]>
Reviewed-by: Larysa Zaremba <[email protected]>
Reviewed-by: Joe Damato <[email protected]>
Signed-off-by: Paolo Abeni <[email protected]>

drivers/net/ethernet/stmicro/stmmac/stmmac_main.c

@@ -5429,7 +5429,9 @@ static int stmmac_rx(struct stmmac_priv *priv, int limit, u32 queue)
 
 			dma_sync_single_for_cpu(priv->device, buf->addr,
 						buf1_len, dma_dir);
-			prefetch(page_address(buf->page) + buf->page_offset);
+			net_prefetch(page_address(buf->page) +
+				buf->page_offset);
+
 			xdp_init_buff(&ctx.xdp, buf_sz, &rx_q->xdp_rxq);
 			xdp_prepare_buff(&ctx.xdp, page_address(buf->page),
 					 buf->page_offset, buf1_len, true);