Re: Question about barriers for ARM on tools/perf/

From: Will Deacon <will.deacon@arm.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>,
	Ingo Molnar <mingo@kernel.org>, David Ahern <dsahern@gmail.com>,
	Jiri Olsa <jolsa@redhat.com>, Namhyung Kim <namhyung@gmail.com>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: Question about barriers for ARM on tools/perf/
Date: Fri, 8 May 2015 17:45:35 +0100	[thread overview]
Message-ID: <20150508164534.GK25587@arm.com> (raw)
In-Reply-To: <20150508152759.GO27504@twins.programming.kicks-ass.net>

On Fri, May 08, 2015 at 04:27:59PM +0100, Peter Zijlstra wrote:
> On Fri, May 08, 2015 at 11:57:01AM -0300, Arnaldo Carvalho de Melo wrote:
> > Em Fri, May 08, 2015 at 03:48:20PM +0100, Will Deacon escreveu:
> 
> > > Do you know what the objection to the intrinsics was? I believe that
> > > the __sync versions are deprecated in favour of the C11-like __atomic
> > > flavours, so if that was all the objection was about then we could use
> > > one or the other depending on what the compiler supports.
> > 
> > Peter? Ingo?
> 
> I cannot remember, the __sync things should mostly work I suppose, and
> if you wrap then in the normal atomic interface we don't have to learn
> yet another API.

Yeah, I think that's a good idea.

> That said, I've successfully lifted this kernel code into userspace in
> the past.

Lifting a copy isn't too bad, it's using the same file that worries me.

Will