Re: [PATCH 02/29] x86, tsx: Add RTM intrinsics

Michael Neuling
2013-03-25T08:54:24Z

Andi Kleen <ak@linux.intel.com> wrote:

> > FYI the TM spec can be downloaded here:
> > https://www.power.org/documentation/power-isa-transactional-memory/
> >
> > You're example code looks like this:
>
> I don't think portable code will use this directly. Note it's in arch/x86/
>
> Generally portable code should use higher level interfaces, like
> elide_lock/elide_lock_adapt that hide the architecture specific
> details.
>
> If you want to do lock elision you would plug in some elision
> algorithm that works well at that level.
>
> > Secondly, can we make xbegin just return true/false and get the status
> > later if needed?
>
> I now removed xbegin() from the portable file, as it's only used
> in arch specific code.

OK, well most of my objections go away now.

> And FWIW I'm considering to change it to save a few instructions and
> go for the more efficient goto based interface in glibc.
>
> >
> > ppc = tcheck... should be fine, other than the name.
>
> Well x and tm doesn't really matter, but I already have x* so i'm inclined
> to keep it, unless people bikeshed too strongly. It should work for PPC too.

Well if you're moving it out of generic code then it doesn't really
matter anymore.

Mikey

>
> BTW if the percpu include loop hell is ever sorted out _xtest may
> even stop using XTEST.