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Re: [RFC 00/17] Pile o' entry stack changes

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On Wed, Sep 6, 2017 at 3:16 PM, Andi Kleen <andi@firstfloor.org> wrote:
> Andy Lutomirski <luto@kernel.org> writes:
>>
>>  - Lots of people (Linus included) have asked to convert the entry
>>    code to pop registers on exit instead of movqing them off the
>>    stack.  This makes a bunch of progress in that direction.
>
> You should benchmark it on Atoms. Likely it's a regression there
> because they don't have the special PUSH/POP acceleration.

I'm not entirely sure this is a worthwhile reason.  Atom will lose a
few cycles due to POP throughput, but there's a lot less decode
bandwidth needed and we save a cache line or two.

--Andy

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[RFC 00/17] Pile o' entry stack changes Andy Lutomirski <luto@kernel.org> - 2017-09-06 23:50 +0200
  [RFC 04/17] x86/asm/64: Simplify reg restore code in the standard IRET paths Andy Lutomirski <luto@kernel.org> - 2017-09-06 23:50 +0200
  [RFC 03/17] x86/asm/64: Move SWAPGS into the common iret-to-usermode path Andy Lutomirski <luto@kernel.org> - 2017-09-06 23:50 +0200
  [RFC 02/17] x86/asm/64: Split the iret-to-user and iret-to-kernel paths Andy Lutomirski <luto@kernel.org> - 2017-09-06 23:50 +0200
  Re: [RFC 00/17] Pile o' entry stack changes Andi Kleen <andi@firstfloor.org> - 2017-09-07 00:20 +0200
    Re: [RFC 00/17] Pile o' entry stack changes Andy Lutomirski <luto@kernel.org> - 2017-09-07 02:10 +0200
      Re: [RFC 00/17] Pile o' entry stack changes Ingo Molnar <mingo@kernel.org> - 2017-09-07 09:10 +0200

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