[PATCH net-next] net: inline napi_skb_cache_get()

[PATCH net-next] net: inline napi_skb_cache_get()

[Eric Dumazet]

clang is inlining it already, gcc (14.2) does not.

Small space cost (215 bytes on x86_64) but faster sk_buff allocations.

$ scripts/bloat-o-meter -t net/core/skbuff.gcc.before.o net/core/skbuff.gcc.after.o
add/remove: 0/1 grow/shrink: 4/1 up/down: 359/-144 (215)
Function                                     old     new   delta
__alloc_skb                                  471     611    +140
napi_build_skb                               245     363    +118
napi_alloc_skb                               331     416     +85
skb_copy_ubufs                              1869    1885     +16
skb_shift                                   1445    1413     -32
napi_skb_cache_get                           112       -    -112
Total: Before=59941, After=60156, chg +0.36%

Signed-off-by: Eric Dumazet <edumazet@google.com>
---
 net/core/skbuff.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index a56133902c0d9c47b45a4a19b228b151456e5051..9e94590914b7f9b1cc748262c73eb5aa4f9d2df8 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -280,7 +280,7 @@ EXPORT_SYMBOL(__netdev_alloc_frag_align);
  */
 static u32 skbuff_cache_size __read_mostly;
 
-static struct sk_buff *napi_skb_cache_get(bool alloc)
+static inline struct sk_buff *napi_skb_cache_get(bool alloc)
 {
 	struct napi_alloc_cache *nc = this_cpu_ptr(&napi_alloc_cache);
 	struct sk_buff *skb;
-- 
2.52.0.457.g6b5491de43-goog

Re: [PATCH net-next] net: inline napi_skb_cache_get()

[Paolo Abeni]

On 1/12/26 2:15 PM, Eric Dumazet wrote:
> clang is inlining it already, gcc (14.2) does not.
> 
> Small space cost (215 bytes on x86_64) but faster sk_buff allocations.
> 
> $ scripts/bloat-o-meter -t net/core/skbuff.gcc.before.o net/core/skbuff.gcc.after.o
> add/remove: 0/1 grow/shrink: 4/1 up/down: 359/-144 (215)
> Function                                     old     new   delta
> __alloc_skb                                  471     611    +140
> napi_build_skb                               245     363    +118
> napi_alloc_skb                               331     416     +85
> skb_copy_ubufs                              1869    1885     +16
> skb_shift                                   1445    1413     -32
> napi_skb_cache_get                           112       -    -112
> Total: Before=59941, After=60156, chg +0.36%
> 
> Signed-off-by: Eric Dumazet <edumazet@google.com>

Not blocking this patch, but I'm wondering if we should consider
defining an 'inline_for_performance' macro for both documentation
purpose and to allow no inline for size-sensitive build.

Paolo

Re: [PATCH net-next] net: inline napi_skb_cache_get()

[Eric Dumazet]

On Thu, Jan 15, 2026 at 12:29 PM Paolo Abeni <pabeni@redhat.com> wrote:
>
> On 1/12/26 2:15 PM, Eric Dumazet wrote:
> > clang is inlining it already, gcc (14.2) does not.
> >
> > Small space cost (215 bytes on x86_64) but faster sk_buff allocations.
> >
> > $ scripts/bloat-o-meter -t net/core/skbuff.gcc.before.o net/core/skbuff.gcc.after.o
> > add/remove: 0/1 grow/shrink: 4/1 up/down: 359/-144 (215)
> > Function                                     old     new   delta
> > __alloc_skb                                  471     611    +140
> > napi_build_skb                               245     363    +118
> > napi_alloc_skb                               331     416     +85
> > skb_copy_ubufs                              1869    1885     +16
> > skb_shift                                   1445    1413     -32
> > napi_skb_cache_get                           112       -    -112
> > Total: Before=59941, After=60156, chg +0.36%
> >
> > Signed-off-by: Eric Dumazet <edumazet@google.com>
>
> Not blocking this patch, but I'm wondering if we should consider
> defining an 'inline_for_performance' macro for both documentation
> purpose and to allow no inline for size-sensitive build.

Yes, I saw mm/slub.c was using __fastpath_inline, but conditional to
CONFIG_SLUB_TINY,
and forcing __always_inline

#ifndef CONFIG_SLUB_TINY
#define __fastpath_inline __always_inline
#else
#define __fastpath_inline
#endif

(For some reason clang is not very smart at compiling mm/slub.c, I am
preparing a series to help with that)

Re: [PATCH net-next] net: inline napi_skb_cache_get()

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net-next.git (main)
by Paolo Abeni <pabeni@redhat.com>:

On Mon, 12 Jan 2026 13:15:15 +0000 you wrote:
> clang is inlining it already, gcc (14.2) does not.
> 
> Small space cost (215 bytes on x86_64) but faster sk_buff allocations.
> 
> $ scripts/bloat-o-meter -t net/core/skbuff.gcc.before.o net/core/skbuff.gcc.after.o
> add/remove: 0/1 grow/shrink: 4/1 up/down: 359/-144 (215)
> Function                                     old     new   delta
> __alloc_skb                                  471     611    +140
> napi_build_skb                               245     363    +118
> napi_alloc_skb                               331     416     +85
> skb_copy_ubufs                              1869    1885     +16
> skb_shift                                   1445    1413     -32
> napi_skb_cache_get                           112       -    -112
> Total: Before=59941, After=60156, chg +0.36%
> 
> [...]

Here is the summary with links:
  - [net-next] net: inline napi_skb_cache_get()
    https://git.kernel.org/netdev/net-next/c/d4596891e72c

You are awesome, thank you!
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