Messages in this thread | | | From | Alexey Dobriyan <> | Date | Thu, 26 Oct 2017 14:58:00 +0200 | Subject | Re: [PATCH v3] lib: optimize cpumask_next_and() |
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> - Refactored _find_next_common_bit into _find_next_bit., as suggested > by Yury Norov. This has no adverse effects on the performance side, > as the compiler successfully inlines the code.
1) Gentoo ships 5.4.0 which doesn't inline this code on x86_64 defconfig (which has OPTIMIZE_INLINING).
ffffffff813556c0 <find_next_bit>: ffffffff813556c0: 55 push rbp ffffffff813556c1: 48 89 d1 mov rcx,rdx ffffffff813556c4: 45 31 c0 xor r8d,r8d ffffffff813556c7: 48 89 f2 mov rdx,rsi ffffffff813556ca: 31 f6 xor esi,esi ffffffff813556cc: 48 89 e5 mov rbp,rsp ffffffff813556cf: e8 7c ff ff ff call ffffffff81355650 <_find_next_bit> ffffffff813556d4: 5d pop rbp ffffffff813556d5: c3 ret
2) Making "and" operation to be centerpiece of this code is kind of meh find_next_or_bit() will be hard to implement.
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