• Denys Vlasenko's avatar
    net: force inlining of netif_tx_start/stop_queue, sock_hold, __sock_put · f9a7cbbf
    Denys Vlasenko authored
    Sometimes gcc mysteriously doesn't inline
    very small functions we expect to be inlined. See
        https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66122
    Arguably, gcc should do better, but gcc people aren't willing
    to invest time into it, asking to use __always_inline instead.
    
    With this .config:
    http://busybox.net/~vda/kernel_config_OPTIMIZE_INLINING_and_Os,
    the following functions get deinlined many times.
    
    netif_tx_stop_queue: 207 copies, 590 calls:
    	55                      push   %rbp
    	48 89 e5                mov    %rsp,%rbp
    	f0 80 8f e0 01 00 00 01 lock orb $0x1,0x1e0(%rdi)
    	5d                      pop    %rbp
    	c3                      retq
    
    netif_tx_start_queue: 47 copies, 111 calls
    	55                      push   %rbp
    	48 89 e5                mov    %rsp,%rbp
    	f0 80 a7 e0 01 00 00 fe lock andb $0xfe,0x1e0(%rdi)
    	5d                      pop    %rbp
    	c3                      retq
    
    sock_hold: 39 copies, 124 calls
    	55                      push   %rbp
    	48 89 e5                mov    %rsp,%rbp
    	f0 ff 87 80 00 00 00    lock incl 0x80(%rdi)
    	5d                      pop    %rbp
    	c3                      retq
    
    __sock_put: 6 copies, 13 calls
    	55                      push   %rbp
    	48 89 e5                mov    %rsp,%rbp
    	f0 ff 8f 80 00 00 00    lock decl 0x80(%rdi)
    	5d                      pop    %rbp
    	c3                      retq
    
    This patch fixes this via s/inline/__always_inline/.
    
    Code size decrease after the patch is ~2.5k:
    
        text      data      bss       dec     hex filename
    56719876  56364551 36196352 149280779 8e5d80b vmlinux_before
    56717440  56364551 36196352 149278343 8e5ce87 vmlinux
    Signed-off-by: default avatarDenys Vlasenko <dvlasenk@redhat.com>
    CC: David S. Miller <davem@davemloft.net>
    CC: linux-kernel@vger.kernel.org
    CC: netdev@vger.kernel.org
    CC: netfilter-devel@vger.kernel.org
    Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
    f9a7cbbf
sock.h 61.6 KB