[PATCH v3 28/32] powerpc/64s: interrupt implement exit logic in C

[Christophe Leroy]

Le 25/02/2020 à 18:35, Nicholas Piggin a écrit :
> Implement the bulk of interrupt return logic in C. The asm return code
> must handle a few cases: restoring full GPRs, and emulating stack store.
> 
> The stack store emulation is significantly simplfied, rather than creating
> a new return frame and switching to that before performing the store, it
> uses the PACA to keep a scratch register around to perform thestore.
> 
> The asm return code is moved into 64e for now. The new logic has made
> allowance for 64e, but I don't have a full environment that works well
> to test it, and even booting in emulated qemu is not great for stress
> testing. 64e shouldn't be too far off working with this, given a bit
> more testing and auditing of the logic.
> 
> This is slightly faster on a POWER9 (page fault speed increases about
> 1.1%), probably due to reduced mtmsrd.
> 

How do you measure 'page fault' speed ?