> -----Original Message-----
> From: Paolo Bonzini [mailto:[email protected]] On Behalf Of Paolo
> Bonzini
> Sent: Friday, January 05, 2018 3:32 AM
> To: Van De Ven, Arjan <[email protected]>; Linus Torvalds
> <[email protected]>; David Woodhouse <[email protected]>
> Cc: Tim Chen <[email protected]>; Thomas Gleixner
> <[email protected]>; Andy Lutomirski <[email protected]>; Greg KH
> <[email protected]>; Hansen, Dave <[email protected]>;
> Andrea Arcangeli <[email protected]>; Andi Kleen <[email protected]>;
> Linux Kernel Mail
> > personally I am comfortable with retpoline on Skylake, but I would
> > like to have IBRS as an opt in for the paranoid.
> >
>
> IBRS actually seems to perform more than decently on Skylake with the
> microcode updates we're shipping in RHEL---much more so than Broadwell
> or Haswell. Can you confirm that this is expected?
Retpoline outperforms IBRS even on skylake family (including the client
kabylake etc)
by some real margin, but IBRS is certainly not the end of the world either...
more a case of 'we can do even faster'. The difference also gets bigger in
retpoline's favor for older generations cpus.
