[PATCH net-next v4 4/4] mvneta: recycle buffers

Matteo Croce
2021-05-11T13:34:20Z

From: Matteo Croce <mcroce@microsoft.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@microsoft.com>
---
drivers/net/ethernet/marvell/mvneta.c | 11 +++++++----
1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/drivers/net/ethernet/marvell/mvneta.c b/drivers/net/ethernet/marvell/mvneta.c
index 7d5cd9bc6c99..6d2f8dce4900 100644
--- a/drivers/net/ethernet/marvell/mvneta.c
+++ b/drivers/net/ethernet/marvell/mvneta.c
@@ -2320,7 +2320,7 @@ mvneta_swbm_add_rx_fragment(struct mvneta_port *pp,
}

static struct sk_buff *
-mvneta_swbm_build_skb(struct mvneta_port *pp, struct mvneta_rx_queue *rxq,
+mvneta_swbm_build_skb(struct mvneta_port *pp, struct page_pool *pool,
struct xdp_buff *xdp, u32 desc_status)
{
struct skb_shared_info *sinfo = xdp_get_shared_info_from_buff(xdp);
@@ -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), pool);

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), pool);
}

return skb;
@@ -2425,7 +2428,7 @@ static int mvneta_rx_swbm(struct napi_struct *napi,
mvneta_run_xdp(pp, rxq, xdp_prog, &xdp_buf, frame_sz, &ps))
goto next;

- skb = mvneta_swbm_build_skb(pp, rxq, &xdp_buf, desc_status);
+ skb = mvneta_swbm_build_skb(pp, pp, &xdp_buf, desc_status);
if (IS_ERR(skb)) {
struct mvneta_pcpu_stats *stats = this_cpu_ptr(pp->stats);

--
2.31.1