Re: [PATCH v5 net-next 09/11] skbuff: allow to optionally use NAPI cache from __alloc_skb()
From: Alexander Duyck <hidden>
Date: 2021-02-12 03:19:56
Also in:
lkml
On Thu, Feb 11, 2021 at 11:00 AM Alexander Lobakin [off-list ref] wrote:
quoted hunk ↗ jump to hunk
Reuse the old and forgotten SKB_ALLOC_NAPI to add an option to get an skbuff_head from the NAPI cache instead of inplace allocation inside __alloc_skb(). This implies that the function is called from softirq or BH-off context, not for allocating a clone or from a distant node. Signed-off-by: Alexander Lobakin <redacted> --- net/core/skbuff.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-)diff --git a/net/core/skbuff.c b/net/core/skbuff.c index 9e1a8ded4acc..a0b457ae87c2 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c@@ -397,15 +397,20 @@ struct sk_buff *__alloc_skb(unsigned int size, gfp_t gfp_mask, struct sk_buff *skb; u8 *data; bool pfmemalloc; + bool clone; - cache = (flags & SKB_ALLOC_FCLONE) - ? skbuff_fclone_cache : skbuff_head_cache; + clone = !!(flags & SKB_ALLOC_FCLONE);
The boolean conversion here is probably unnecessary. I would make clone an int like flags and work with that. I suspect the compiler is doing it already, but it is better to be explicit.
+ cache = clone ? skbuff_fclone_cache : skbuff_head_cache;
if (sk_memalloc_socks() && (flags & SKB_ALLOC_RX))
gfp_mask |= __GFP_MEMALLOC;
/* Get the HEAD */
- skb = kmem_cache_alloc_node(cache, gfp_mask & ~__GFP_DMA, node);
+ if ((flags & SKB_ALLOC_NAPI) && !clone &&
Rather than having to do two checks you could just check for
SKB_ALLOC_NAPI and SKB_ALLOC_FCLONE in a single check. You could just
do something like:
if ((flags & (SKB_ALLOC_FCLONE | SKB_ALLOC_NAPI) == SKB_ALLOC_NAPI)
That way you can avoid the extra conditional jumps and can start
computing the flags value sooner.
quoted hunk ↗ jump to hunk
+ likely(node == NUMA_NO_NODE || node == numa_mem_id())) + skb = napi_skb_cache_get(); + else + skb = kmem_cache_alloc_node(cache, gfp_mask & ~GFP_DMA, node); if (unlikely(!skb)) return NULL; prefetchw(skb);@@ -436,7 +441,7 @@ struct sk_buff *__alloc_skb(unsigned int size, gfp_t gfp_mask, __build_skb_around(skb, data, 0); skb->pfmemalloc = pfmemalloc; - if (flags & SKB_ALLOC_FCLONE) { + if (clone) { struct sk_buff_fclones *fclones; fclones = container_of(skb, struct sk_buff_fclones, skb1); --2.30.1