x86/asm: Force inlining of cpu_relax()
On x86, cpu_relax() simply calls rep_nop(), which generates one instruction, PAUSE (aka REP NOP). With this config: http://busybox.net/~vda/kernel_config_OPTIMIZE_INLINING_and_Os gcc-4.7.2 does not always inline rep_nop(): it generates several copies of this: <rep_nop> (16 copies, 194 calls): 55 push %rbp 48 89 e5 mov %rsp,%rbp f3 90 pause 5d pop %rbp c3 retq See: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66122 This patch fixes this via s/inline/__always_inline/ on rep_nop() and cpu_relax(). ( Forcing inlining only on rep_nop() causes GCC to deinline cpu_relax(), with almost no change in generated code). text data bss dec hex filename 88118971 19905208 36421632 144445811 89c1173 vmlinux.before 88118139 19905208 36421632 144444979 89c0e33 vmlinux Signed-off-by:Denys Vlasenko <dvlasenk@redhat.com> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Link: http://lkml.kernel.org/r/1443096149-27291-1-git-send-email-dvlasenk@redhat.comSigned-off-by:
Ingo Molnar <mingo@kernel.org>
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