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Groups > linux.kernel > #1464714
| From | Denys Vlasenko <dvlasenk@redhat.com> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: RFC: Petition Intel/AMD to add POPF_IF insn |
| Date | 2016-08-17 20:40 +0200 |
| Message-ID | <s7dUR-4LA-5@gated-at.bofh.it> (permalink) |
| References | <s7cP7-469-1@gated-at.bofh.it> <s7dUR-4LA-7@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
On 08/17/2016 07:30 PM, Christian König wrote: >> But in my measurements POPF is not fast even in the case where restored >> flags are not changed at all: >> >> mov $200*1000*1000, %eax >> pushf >> pop %rbx >> .balign 64 >> loop: push %rbx >> popf >> dec %eax >> jnz loop >> >> # perf stat -r20 ./popf_1g >> 4,929,012,093 cycles # 3.412 GHz ( +- 0.02% ) >> 835,721,371 instructions # 0.17 insn per cycle ( +- 0.02% ) >> 1.446185359 seconds time elapsed ( +- 0.46% ) >> >> If I replace POPF with a pop into an unused register, I get this: > > You are comparing apples and bananas here. Yes, I know. Pop into a register here is basically free. I'd also add a STI and measure how much it takes to enable interrupts, but unfortunately STI throws a #GP in CPL 3.
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RFC: Petition Intel/AMD to add POPF_IF insn Denys Vlasenko <dvlasenk@redhat.com> - 2016-08-17 19:30 +0200
Re: RFC: Petition Intel/AMD to add POPF_IF insn Linus Torvalds <torvalds@linux-foundation.org> - 2016-08-17 20:00 +0200
Re: RFC: Petition Intel/AMD to add POPF_IF insn Denys Vlasenko <dvlasenk@redhat.com> - 2016-08-17 21:00 +0200
Re: RFC: Petition Intel/AMD to add POPF_IF insn Andy Lutomirski <luto@amacapital.net> - 2016-08-17 21:20 +0200
Re: RFC: Petition Intel/AMD to add POPF_IF insn Denys Vlasenko <dvlasenk@redhat.com> - 2016-08-17 21:30 +0200
Re: RFC: Petition Intel/AMD to add POPF_IF insn Denys Vlasenko <dvlasenk@redhat.com> - 2016-08-17 21:40 +0200
Re: RFC: Petition Intel/AMD to add POPF_IF insn Linus Torvalds <torvalds@linux-foundation.org> - 2016-08-17 22:00 +0200
Re: RFC: Petition Intel/AMD to add POPF_IF insn Linus Torvalds <torvalds@linux-foundation.org> - 2016-08-17 21:40 +0200
Re: RFC: Petition Intel/AMD to add POPF_IF insn Linus Torvalds <torvalds@linux-foundation.org> - 2016-08-17 23:30 +0200
Re: RFC: Petition Intel/AMD to add POPF_IF insn Linus Torvalds <torvalds@linux-foundation.org> - 2016-08-17 23:40 +0200
Re: RFC: Petition Intel/AMD to add POPF_IF insn Andy Lutomirski <luto@amacapital.net> - 2016-08-17 23:50 +0200
Re: RFC: Petition Intel/AMD to add POPF_IF insn Linus Torvalds <torvalds@linux-foundation.org> - 2016-08-18 00:40 +0200
Re: RFC: Petition Intel/AMD to add POPF_IF insn Denys Vlasenko <dvlasenk@redhat.com> - 2016-08-18 15:30 +0200
Re: RFC: Petition Intel/AMD to add POPF_IF insn Denys Vlasenko <dvlasenk@redhat.com> - 2016-08-19 03:00 +0200
Re: RFC: Petition Intel/AMD to add POPF_IF insn Denys Vlasenko <dvlasenk@redhat.com> - 2016-08-19 03:10 +0200
Re: RFC: Petition Intel/AMD to add POPF_IF insn Linus Torvalds <torvalds@linux-foundation.org> - 2016-08-19 04:30 +0200
Re: RFC: Petition Intel/AMD to add POPF_IF insn Paolo Bonzini <pbonzini@redhat.com> - 2016-08-19 13:00 +0200
Re: RFC: Petition Intel/AMD to add POPF_IF insn Denys Vlasenko <dvlasenk@redhat.com> - 2016-08-18 11:30 +0200
Re: RFC: Petition Intel/AMD to add POPF_IF insn Denys Vlasenko <dvlasenk@redhat.com> - 2016-08-18 14:20 +0200
Re: RFC: Petition Intel/AMD to add POPF_IF insn Paolo Bonzini <pbonzini@redhat.com> - 2016-08-19 04:10 +0200
Re: RFC: Petition Intel/AMD to add POPF_IF insn Linus Torvalds <torvalds@linux-foundation.org> - 2016-08-17 21:50 +0200
Re: RFC: Petition Intel/AMD to add POPF_IF insn Linus Torvalds <torvalds@linux-foundation.org> - 2016-08-17 21:30 +0200
Re: RFC: Petition Intel/AMD to add POPF_IF insn Denys Vlasenko <dvlasenk@redhat.com> - 2016-08-17 20:40 +0200
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