On Thu, 2016-15-09 at 09:04:46 UTC, Nicholas Piggin wrote:
> mtmsrd with L=1 only affects MSR_EE and MSR_RI bits, and we always
> know what state those bits are, so the kernel MSR does not need to be
> loaded when modifying them.
>
> mtmsrd is often in the critical execution path, so avoiding depe
On Tue, 20 Sep 2016 14:25:48 +1000
Michael Ellerman wrote:
> Nicholas Piggin writes:
>
> > mtmsrd with L=1 only affects MSR_EE and MSR_RI bits, and we always
> > know what state those bits are, so the kernel MSR does not need to be
> > loaded when modifying them.
> >
> > mtmsrd is often in the
Nicholas Piggin writes:
> mtmsrd with L=1 only affects MSR_EE and MSR_RI bits, and we always
> know what state those bits are, so the kernel MSR does not need to be
> loaded when modifying them.
>
> mtmsrd is often in the critical execution path, so avoiding dependency
> on even L1 load is notica
mtmsrd with L=1 only affects MSR_EE and MSR_RI bits, and we always
know what state those bits are, so the kernel MSR does not need to be
loaded when modifying them.
mtmsrd is often in the critical execution path, so avoiding dependency
on even L1 load is noticable. On a POWER8 this saves about 3 c
