target/linux/generic/pending-4.19/650-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