netdev - [PATCH net-next 5/5] skbuff: refill skb_cache early from deferred-to-consume entries

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Date:   Mon, 11 Jan 2021 18:29:44 +0000
From:   Alexander Lobakin <alobakin@...me>
To:     "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>
Cc:     Eric Dumazet <edumazet@...gle.com>,
        Edward Cree <ecree@...arflare.com>,
        Jonathan Lemon <jonathan.lemon@...il.com>,
        Willem de Bruijn <willemb@...gle.com>,
        Miaohe Lin <linmiaohe@...wei.com>,
        Alexander Lobakin <alobakin@...me>,
        Steffen Klassert <steffen.klassert@...unet.com>,
        Guillaume Nault <gnault@...hat.com>,
        Yadu Kishore <kyk.segfault@...il.com>,
        Al Viro <viro@...iv.linux.org.uk>, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH net-next 5/5] skbuff: refill skb_cache early from deferred-to-consume entries

Instead of unconditional queueing of ready-to-consume skbuff_heads
to flush_skb_cache, feed skb_cache with them instead if it's not
full already.
This greatly reduces the frequency of kmem_cache_alloc_bulk() calls.

Signed-off-by: Alexander Lobakin <alobakin@...me>
---
 net/core/skbuff.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 57a7307689f3..ba0d5611635e 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -904,6 +904,11 @@ static inline void _kfree_skb_defer(struct sk_buff *skb)
 	/* drop skb->head and call any destructors for packet */
 	skb_release_all(skb);
 
+	if (nc->skb_count < NAPI_SKB_CACHE_SIZE) {
+		nc->skb_cache[nc->skb_count++] = skb;
+		return;
+	}
+
 	/* record skb to CPU local list */
 	nc->flush_skb_cache[nc->flush_skb_count++] = skb;
 
-- 
2.30.0