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

[Andy Lutomirski]

On Wed, Sep 6, 2017 at 3:16 PM, Andi Kleen <andi@xxxxxxxxxxxxxx> wrote:
> Andy Lutomirski <luto@xxxxxxxxxx> 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