[PATCH net-next 6/6] mvneta: recycle buffers

Matteo Croce
2021-03-22T17:05:31Z

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 | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/marvell/mvneta.c b/drivers/net/ethernet/marvell/mvneta.c
index a635cf84608a..8b3250394703 100644
--- a/drivers/net/ethernet/marvell/mvneta.c
+++ b/drivers/net/ethernet/marvell/mvneta.c
@@ -2332,7 +2332,7 @@ 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);
@@ -2344,7 +2344,7 @@ 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));
+ skb_mark_for_recycle(skb, skb_frag_page(frag), &xdp->rxq->mem);
}

return skb;
--
2.30.2