linux-kernel - [PATCH net-next v2 5/5] mvneta: recycle buffers

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Message-Id: <20210402181733.32250-6-mcroce@linux.microsoft.com>
Date:   Fri,  2 Apr 2021 20:17:33 +0200
From:   Matteo Croce <mcroce@...ux.microsoft.com>
To:     netdev@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org,
        Jonathan Lemon <jonathan.lemon@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Ilias Apalodimas <ilias.apalodimas@...aro.org>,
        Jesper Dangaard Brouer <hawk@...nel.org>,
        Lorenzo Bianconi <lorenzo@...nel.org>,
        Saeed Mahameed <saeedm@...dia.com>,
        David Ahern <dsahern@...il.com>,
        Saeed Mahameed <saeed@...nel.org>, Andrew Lunn <andrew@...n.ch>
Subject: [PATCH net-next v2 5/5] mvneta: recycle buffers

From: Matteo Croce <mcroce@...rosoft.com>

Use the new recycling API for page_pool.
In a drop rate test, the packet rate increased di 10%,
from 269 Kpps to 296 Kpps.

perf top on a stock system shows:

Overhead  Shared Object     Symbol
  21.78%  [kernel]          [k] __pi___inval_dcache_area
  21.66%  [mvneta]          [k] mvneta_rx_swbm
   7.00%  [kernel]          [k] kmem_cache_alloc
   6.05%  [kernel]          [k] eth_type_trans
   4.44%  [kernel]          [k] kmem_cache_free.part.0
   3.80%  [kernel]          [k] __netif_receive_skb_core
   3.68%  [kernel]          [k] dev_gro_receive
   3.65%  [kernel]          [k] get_page_from_freelist
   3.43%  [kernel]          [k] page_pool_release_page
   3.35%  [kernel]          [k] free_unref_page

And this is the same output with recycling enabled:

Overhead  Shared Object     Symbol
  24.10%  [kernel]          [k] __pi___inval_dcache_area
  23.02%  [mvneta]          [k] mvneta_rx_swbm
   7.19%  [kernel]          [k] kmem_cache_alloc
   6.50%  [kernel]          [k] eth_type_trans
   4.93%  [kernel]          [k] __netif_receive_skb_core
   4.77%  [kernel]          [k] kmem_cache_free.part.0
   3.93%  [kernel]          [k] dev_gro_receive
   3.03%  [kernel]          [k] build_skb
   2.91%  [kernel]          [k] page_pool_put_page
   2.85%  [kernel]          [k] __xdp_return

The test was done with mausezahn on the TX side with 64 byte raw
ethernet frames.

Signed-off-by: Matteo Croce <mcroce@...rosoft.com>
---
 drivers/net/ethernet/marvell/mvneta.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/marvell/mvneta.c b/drivers/net/ethernet/marvell/mvneta.c
index f20dfd1d7a6b..f88c189b60a4 100644
--- a/drivers/net/ethernet/marvell/mvneta.c
+++ b/drivers/net/ethernet/marvell/mvneta.c
@@ -2331,7 +2331,7 @@ mvneta_swbm_build_skb(struct mvneta_port *pp, struct mvneta_rx_queue *rxq,
 	if (!skb)
 		return ERR_PTR(-ENOMEM);
 
-	page_pool_release_page(rxq->page_pool, virt_to_page(xdp->data));
+	skb_mark_for_recycle(skb, virt_to_page(xdp->data), &xdp->rxq->mem);
 
 	skb_reserve(skb, xdp->data - xdp->data_hard_start);
 	skb_put(skb, xdp->data_end - xdp->data);
@@ -2343,7 +2343,10 @@ mvneta_swbm_build_skb(struct mvneta_port *pp, struct mvneta_rx_queue *rxq,
 		skb_add_rx_frag(skb, skb_shinfo(skb)->nr_frags,
 				skb_frag_page(frag), skb_frag_off(frag),
 				skb_frag_size(frag), PAGE_SIZE);
-		page_pool_release_page(rxq->page_pool, skb_frag_page(frag));
+		/* We don't need to reset pp_recycle here. It's already set, so
+		 * just mark fragments for recycling.
+		 */
+		page_pool_store_mem_info(skb_frag_page(frag), &xdp->rxq->mem);
 	}
 
 	return skb;
-- 
2.30.2