diff options
| author | Eric Dumazet <edumazet@google.com> | 2025-10-16 18:29:11 +0000 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2025-10-20 17:37:57 -0700 |
| commit | a5cd3a60aa1d0366265638c43012e1ac1b3f6d6a (patch) | |
| tree | 91d9a2b42314ae51cc0e1618f794de607c003632 /net/core | |
| parent | 6ae022f8ac7ad581c31d3309afacdb8e33ef9c7f (diff) | |
net: shrink napi_skb_cache_{put,get}() and napi_skb_cache_get_bulk()
Following loop in napi_skb_cache_put() is unrolled by the compiler
even if CONFIG_KASAN is not enabled:
for (i = NAPI_SKB_CACHE_HALF; i < NAPI_SKB_CACHE_SIZE; i++)
kasan_mempool_unpoison_object(nc->skb_cache[i],
kmem_cache_size(net_hotdata.skbuff_cache));
We have 32 times this sequence, for a total of 384 bytes.
48 8b 3d 00 00 00 00 net_hotdata.skbuff_cache,%rdi
e8 00 00 00 00 call kmem_cache_size
This is because kmem_cache_size() is not an inline and not const,
and kasan_unpoison_object_data() is an inline function.
Cache kmem_cache_size() result in a variable, so that
the compiler can remove dead code (and variable) when/if
CONFIG_KASAN is unset.
After this patch, napi_skb_cache_put() is inlined in its callers,
and we avoid one kmem_cache_size() call in napi_skb_cache_get()
and napi_skb_cache_get_bulk().
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@google.com>
Reviewed-by: Alexander Lobakin <aleksander.lobakin@intel.com>
Link: https://patch.msgid.link/20251016182911.1132792-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'net/core')
| -rw-r--r-- | net/core/skbuff.c | 15 |
1 files changed, 10 insertions, 5 deletions
diff --git a/net/core/skbuff.c b/net/core/skbuff.c index 8eb3c5820724..5b4bc8b1c7d5 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -274,6 +274,11 @@ void *__netdev_alloc_frag_align(unsigned int fragsz, unsigned int align_mask) } EXPORT_SYMBOL(__netdev_alloc_frag_align); +/* Cache kmem_cache_size(net_hotdata.skbuff_cache) to help the compiler + * remove dead code (and skbuff_cache_size) when CONFIG_KASAN is unset. + */ +static u32 skbuff_cache_size __read_mostly; + static struct sk_buff *napi_skb_cache_get(void) { struct napi_alloc_cache *nc = this_cpu_ptr(&napi_alloc_cache); @@ -293,7 +298,7 @@ static struct sk_buff *napi_skb_cache_get(void) skb = nc->skb_cache[--nc->skb_count]; local_unlock_nested_bh(&napi_alloc_cache.bh_lock); - kasan_mempool_unpoison_object(skb, kmem_cache_size(net_hotdata.skbuff_cache)); + kasan_mempool_unpoison_object(skb, skbuff_cache_size); return skb; } @@ -345,11 +350,9 @@ u32 napi_skb_cache_get_bulk(void **skbs, u32 n) get: for (u32 base = nc->skb_count - n, i = 0; i < n; i++) { - u32 cache_size = kmem_cache_size(net_hotdata.skbuff_cache); - skbs[i] = nc->skb_cache[base + i]; - kasan_mempool_unpoison_object(skbs[i], cache_size); + kasan_mempool_unpoison_object(skbs[i], skbuff_cache_size); memset(skbs[i], 0, offsetof(struct sk_buff, tail)); } @@ -1437,7 +1440,7 @@ static void napi_skb_cache_put(struct sk_buff *skb) if (unlikely(nc->skb_count == NAPI_SKB_CACHE_SIZE)) { for (i = NAPI_SKB_CACHE_HALF; i < NAPI_SKB_CACHE_SIZE; i++) kasan_mempool_unpoison_object(nc->skb_cache[i], - kmem_cache_size(net_hotdata.skbuff_cache)); + skbuff_cache_size); kmem_cache_free_bulk(net_hotdata.skbuff_cache, NAPI_SKB_CACHE_HALF, nc->skb_cache + NAPI_SKB_CACHE_HALF); @@ -5125,6 +5128,8 @@ void __init skb_init(void) offsetof(struct sk_buff, cb), sizeof_field(struct sk_buff, cb), NULL); + skbuff_cache_size = kmem_cache_size(net_hotdata.skbuff_cache); + net_hotdata.skbuff_fclone_cache = kmem_cache_create("skbuff_fclone_cache", sizeof(struct sk_buff_fclones), 0, |