From: Matteo Croce mcroce@microsoft.com
mainline inclusion from mainline-v5.14-rc1 commit d8ea89fe8a49 category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/I4CVS3 CVE: NA
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...
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In the RX buffer, the received data starts after a headroom used to align the IP header and to allow prepending headers efficiently. The prefetch() should take this into account, and prefetch from the very start of the received data.
We can see that ether_addr_equal_64bits(), which is the first function to access the data, drops from the top of the perf top output.
prefetch(data):
Overhead Shared Object Symbol 11.64% [kernel] [k] eth_type_trans
prefetch(data + MVPP2_MH_SIZE + MVPP2_SKB_HEADROOM):
Overhead Shared Object Symbol 13.42% [kernel] [k] build_skb 10.35% [mvpp2] [k] mvpp2_rx 9.35% [kernel] [k] __netif_receive_skb_core 8.24% [kernel] [k] kmem_cache_free 7.97% [kernel] [k] dev_gro_receive 7.68% [kernel] [k] page_pool_put_page 7.32% [kernel] [k] kmem_cache_alloc 7.09% [mvpp2] [k] mvpp2_bm_pool_put 3.36% [kernel] [k] eth_type_trans
Also, move the eth_type_trans() call a bit down, to give the RAM more time to prefetch the data.
Signed-off-by: Matteo Croce mcroce@microsoft.com Signed-off-by: David S. Miller davem@davemloft.net Reviewed-by: Yongxin Li liyongxin1@huawei.com Signed-off-by: Junxin Chen chenjunxin1@huawei.com Signed-off-by: Zheng Zengkai zhengzengkai@huawei.com --- drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c b/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c index e4360b1803bf..55c6f90f818b 100644 --- a/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c +++ b/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c @@ -3580,7 +3580,7 @@ static int mvpp2_rx(struct mvpp2_port *port, struct napi_struct *napi, goto err_drop_frame;
/* Prefetch header */ - prefetch(data); + prefetch(data + MVPP2_MH_SIZE + MVPP2_SKB_HEADROOM);
if (bm_pool->frag_size > PAGE_SIZE) frag_size = 0; @@ -3650,8 +3650,8 @@ static int mvpp2_rx(struct mvpp2_port *port, struct napi_struct *napi,
skb_reserve(skb, MVPP2_MH_SIZE + MVPP2_SKB_HEADROOM); skb_put(skb, rx_bytes); - skb->protocol = eth_type_trans(skb, dev); mvpp2_rx_csum(port, rx_status, skb); + skb->protocol = eth_type_trans(skb, dev);
napi_gro_receive(napi, skb); continue;