Messages in this thread | | | Date | Fri, 25 Sep 2015 13:44:23 +0200 | From | Borislav Petkov <> | Subject | Re: [PATCH] x86/processor.h: Force inlining of cpu_relax() |
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On Thu, Sep 24, 2015 at 02:02:29PM +0200, Denys Vlasenko wrote: > 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
Looks ok to me, text even grows smaller.
Acked-by: Borislav Petkov <bp@suse.de>
-- Regards/Gruss, Boris.
ECO tip #101: Trim your mails when you reply.
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