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net: use NAPI_SKB_CACHE_FREE to keep 32 as default to do bulk free

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- Replace NAPI_SKB_CACHE_HALF with NAPI_SKB_CACHE_FREE
- Only free 32 skbs in napi_skb_cache_put()

Since the first patch adjusting NAPI_SKB_CACHE_SIZE to 128, the number
of packets to be freed in the softirq was increased from 32 to 64.
Considering a subsequent net_rx_action() calling napi_poll() a few
times can easily consume the 64 available slots and we can afford
keeping a higher value of sk_buffs in per-cpu storage, decrease
NAPI_SKB_CACHE_FREE to 32 like before. So now the logic is 1) keeping
96 skbs, 2) freeing 32 skbs at one time.

Suggested-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Jason Xing <kernelxing@tencent.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Alexander Lobakin <aleksander.lobakin@intel.com>
Link: https://patch.msgid.link/20251118070646.61344-4-kerneljasonxing@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Jason Xing
2025-11-18 15:06:45 +08:00
committed by Jakub Kicinski
parent 01d7385618
commit 2d67b5c5c6
1 changed files with 8 additions and 6 deletions
Download Patch File Download Diff File Expand all files Collapse all files

14
net/core/skbuff.c
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@@ -225,7 +225,7 @@ static void skb_under_panic(struct sk_buff *skb, unsigned int sz, void *addr)
#define NAPI_SKB_CACHE_SIZE 128
#define NAPI_SKB_CACHE_BULK 32
#define NAPI_SKB_CACHE_HALF (NAPI_SKB_CACHE_SIZE / 2)
#define NAPI_SKB_CACHE_FREE 32
struct napi_alloc_cache {
local_lock_t bh_lock;
@@ -1445,7 +1445,6 @@ void __consume_stateless_skb(struct sk_buff *skb)
static void napi_skb_cache_put(struct sk_buff *skb)
{
struct napi_alloc_cache *nc = this_cpu_ptr(&napi_alloc_cache);
u32 i;
if (!kasan_mempool_poison_object(skb))
return;
@@ -1454,13 +1453,16 @@ static void napi_skb_cache_put(struct sk_buff *skb)
nc->skb_cache[nc->skb_count++] = skb;
if (unlikely(nc->skb_count == NAPI_SKB_CACHE_SIZE)) {
for (i = NAPI_SKB_CACHE_HALF; i < NAPI_SKB_CACHE_SIZE; i++)
u32 i, remaining = NAPI_SKB_CACHE_SIZE - NAPI_SKB_CACHE_FREE;
for (i = remaining; i < NAPI_SKB_CACHE_SIZE; i++)
kasan_mempool_unpoison_object(nc->skb_cache[i],
skbuff_cache_size);
kmem_cache_free_bulk(net_hotdata.skbuff_cache, NAPI_SKB_CACHE_HALF,
nc->skb_cache + NAPI_SKB_CACHE_HALF);
nc->skb_count = NAPI_SKB_CACHE_HALF;
kmem_cache_free_bulk(net_hotdata.skbuff_cache,
NAPI_SKB_CACHE_FREE,
nc->skb_cache + remaining);
nc->skb_count = remaining;
}
local_unlock_nested_bh(&napi_alloc_cache.bh_lock);
}