kernel: use bulk free in kfree_skb_list to improve performance
[openwrt/openwrt.git] / target / linux / generic / pending-4.14 / 650-net-use-bulk-free-in-kfree_skb_list.patch
1 From: Felix Fietkau <nbd@nbd.name>
2 Date: Sat, 23 Mar 2019 18:26:10 +0100
3 Subject: [PATCH] net: use bulk free in kfree_skb_list
4
5 Since we're freeing multiple skbs, we might as well use bulk free to save a
6 few cycles. Use the same conditions for bulk free as in napi_consume_skb.
7
8 Signed-off-by: Felix Fietkau <nbd@nbd.name>
9 ---
10
11 --- a/net/core/skbuff.c
12 +++ b/net/core/skbuff.c
13 @@ -666,12 +666,44 @@ EXPORT_SYMBOL(kfree_skb);
14
15 void kfree_skb_list(struct sk_buff *segs)
16 {
17 - while (segs) {
18 - struct sk_buff *next = segs->next;
19 + struct sk_buff *next = segs;
20 + void *skbs[16];
21 + int n_skbs = 0;
22
23 - kfree_skb(segs);
24 - segs = next;
25 + while ((segs = next) != NULL) {
26 + next = segs->next;
27 +
28 + if (segs->fclone != SKB_FCLONE_UNAVAILABLE) {
29 + kfree_skb(segs);
30 + continue;
31 + }
32 +
33 + if (!skb_unref(segs))
34 + continue;
35 +
36 + trace_kfree_skb(segs, __builtin_return_address(0));
37 +
38 + /* drop skb->head and call any destructors for packet */
39 + skb_release_all(segs);
40 +
41 +#ifdef CONFIG_SLUB
42 + /* SLUB writes into objects when freeing */
43 + prefetchw(segs);
44 +#endif
45 +
46 + skbs[n_skbs++] = segs;
47 +
48 + if (n_skbs < ARRAY_SIZE(skbs))
49 + continue;
50 +
51 + kmem_cache_free_bulk(skbuff_head_cache, n_skbs, skbs);
52 + n_skbs = 0;
53 }
54 +
55 + if (!n_skbs)
56 + return;
57 +
58 + kmem_cache_free_bulk(skbuff_head_cache, n_skbs, skbs);
59 }
60 EXPORT_SYMBOL(kfree_skb_list);
61