netdev - Re: [PATCH net-next] tcp: split tcp_check

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Message-ID: <CAAVpQUAvyQvZnP3E3PwyX_hRvLSbo3TVsZJaVWFTXWrpYf_9vg@mail.gmail.com>
Date: Tue, 3 Feb 2026 16:30:08 -0800
From: Kuniyuki Iwashima <kuniyu@...gle.com>
To: Eric Dumazet <edumazet@...gle.com>
Cc: "David S . Miller" <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>, 
	Paolo Abeni <pabeni@...hat.com>, Simon Horman <horms@...nel.org>, 
	Neal Cardwell <ncardwell@...gle.com>, netdev@...r.kernel.org, eric.dumazet@...il.com
Subject: Re: [PATCH net-next] tcp: split tcp_check_space() in two parts

On Mon, Feb 2, 2026 at 9:09 PM Eric Dumazet <edumazet@...gle.com> wrote:
>
> tcp_check_space() is fat and not inlined.
>
> Move its slow path in (out of line) __tcp_check_space()
> and make tcp_check_space() an inline function for better TCP performance.
>
> $ scripts/bloat-o-meter -t vmlinux.old vmlinux.new
> add/remove: 2/2 grow/shrink: 4/0 up/down: 708/-582 (126)
> Function                                     old     new   delta
> __tcp_check_space                              -     521    +521
> tcp_rcv_established                         1860    1916     +56
> tcp_rcv_state_process                       3342    3384     +42
> tcp_event_new_data_sent                      248     286     +38
> tcp_data_snd_check                            71     106     +35
> __pfx___tcp_check_space                        -      16     +16
> __pfx_tcp_check_space                         16       -     -16
> tcp_check_space                              566       -    -566
> Total: Before=24896373, After=24896499, chg +0.00%
>
> Signed-off-by: Eric Dumazet <edumazet@...gle.com>

Reviewed-by: Kuniyuki Iwashima <kuniyu@...gle.com>