lkml.org 
[lkml]   [2014]   [Feb]   [7]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [RFC][PATCH 0/5] arch: atomic rework
Hi Paul,

On Fri, Feb 07, 2014 at 04:50:28PM +0000, Paul E. McKenney wrote:
> On Fri, Feb 07, 2014 at 08:44:05AM +0100, Peter Zijlstra wrote:
> > On Thu, Feb 06, 2014 at 08:20:51PM -0800, Paul E. McKenney wrote:
> > > Hopefully some discussion of out-of-thin-air values as well.
> >
> > Yes, absolutely shoot store speculation in the head already. Then drive
> > a wooden stake through its hart.
> >
> > C11/C++11 should not be allowed to claim itself a memory model until that
> > is sorted.
>
> There actually is a proposal being put forward, but it might not make ARM
> and Power people happy because it involves adding a compare, a branch,
> and an ISB/isync after every relaxed load... Me, I agree with you,
> much preferring the no-store-speculation approach.

Can you elaborate a bit on this please? We don't permit speculative stores
in the ARM architecture, so it seems counter-intuitive that GCC needs to
emit any additional instructions to prevent that from happening.

Stores can, of course, be observed out-of-order but that's a lot more
reasonable :)

Will


\
 
 \ /
  Last update: 2014-02-08 04:21    [W:0.324 / U:0.440 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site