On Fri, Mar 4, 2016 at 3:01 PM, Jesper Dangaard Brouer
<bro...@redhat.com> wrote:
> /* build_skb() is wrapper over __build_skb(), that specifically
> * takes care of skb->head and skb->pfmemalloc
> * This means that if @frag_size is not zero, then @data must be backed
> @@ -490,8 +500,8 @@ struct sk_buff *__napi_alloc_skb(struct napi_struct
> *napi, unsigned int len,
>
> len += NET_SKB_PAD + NET_IP_ALIGN;
>
> - if ((len > SKB_WITH_OVERHEAD(PAGE_SIZE)) ||
> - (gfp_mask & (__GFP_DIRECT_RECLAIM | GFP_DMA))) {
> + if (unlikely((len > SKB_WITH_OVERHEAD(PAGE_SIZE)) ||
> + (gfp_mask & (__GFP_DIRECT_RECLAIM | GFP_DMA)))) {
Why unlikely? I know it is better for the common case where most
likely linear SKBs are << SKB_WITH_OVERHEAD(PAGE_SIZE)), but what
about the case of Hardware LRO, where linear SKB is likely to be >>
SKB_WITH_OVERHEAD(PAGE_SIZE)).
> skb = __alloc_skb(len, gfp_mask, SKB_ALLOC_RX, NUMA_NO_NODE);
> if (!skb)
> goto skb_fail;
> @@ -508,11 +518,20 @@ struct sk_buff *__napi_alloc_skb(struct napi_struct
> *napi, unsigned int len,
> if (unlikely(!data))
> return NULL;
>
> - skb = __build_skb(data, len);
> - if (unlikely(!skb)) {
> +#define BULK_ALLOC_SIZE 8
> + if (!nc->skb_count) {
> + nc->skb_count = kmem_cache_alloc_bulk(skbuff_head_cache,
> + gfp_mask,
> BULK_ALLOC_SIZE,
> + nc->skb_cache);
> + }
> + if (likely(nc->skb_count)) {
> + skb = (struct sk_buff *)nc->skb_cache[--nc->skb_count];
> + } else {
> + /* alloc bulk failed */
> skb_free_frag(data);
> return NULL;
> }
> + skb = ___build_skb(data, len, skb);
>
> /* use OR instead of assignment to avoid clearing of bits in mask */
> if (nc->page.pfmemalloc)
>
