On Fri, 12 May 2017 12:58:12 +
David Laight wrote:
> From: Linus Torvalds
> > Sent: 11 May 2017 19:48
> ...
> > The one question I have is about "spin_on_cond()": since you
> > explicitly document that the "no spinning" case is expected to be the
> > default, I really think that the default
On Fri, May 12, 2017 at 5:58 AM, David Laight wrote:
>
> At least some versions of gcc convert while (cond) do {body}
> into if (cond) do {body} while (cond) even when 'cond'
> is a non-trivial expression and 'body' is trivial.
Afaik pretty much all versions of gcc do that, unless you use -Os
(wh
From: Linus Torvalds
> Sent: 11 May 2017 19:48
...
> The one question I have is about "spin_on_cond()": since you
> explicitly document that the "no spinning" case is expected to be the
> default, I really think that the default implementation should be
> along the lines if
>
> #define spin_on_c
On Thu, 11 May 2017 11:47:47 -0700
Linus Torvalds wrote:
> On Thu, May 11, 2017 at 9:57 AM, Nicholas Piggin wrote:
> >
> > If you find this acceptable, I'd like to start wiring in the powerpc
> > and adding the annotations to some important core spin loops (there's
> > not too many really). I'm
On Thu, May 11, 2017 at 9:57 AM, Nicholas Piggin wrote:
>
> If you find this acceptable, I'd like to start wiring in the powerpc
> and adding the annotations to some important core spin loops (there's
> not too many really). I'm hoping if you take this patch during this
> merge window, I'll be abl
Current busy-wait loops are implemented by repeatedly calling cpu_relax()
to give an arch option for a low-latency option to improve power and/or
SMT resource contention.
This poses some difficulties for powerpc, which has SMT priority setting
instructions (priorities determine how ifetch cycles a