Hello,

I just saw this postedon reddit, I'm not sure but I thought it might
be relevant to this discussion.

http://bartoszmilewski.wordpress.com/2008/11/05/who-ordered-memory-fences-on-an-\
x86/

cheers,
Steve

On Fri, Oct 31, 2008 at 2:17 PM, oja_i_i <ml@...> wrote:
> --- In liblf-dev@yahoogroups.com, Bjorn Roche <bjorn@...> wrote:
>>
>>
>> On Oct 30, 2008, at 5:10 PM, James McCartney wrote:
>>
>> > On Wed, Oct 29, 2008 at 11:37 AM, Bjorn Roche <bjorn@...>
>> > wrote:
>> > > Plus, gcc, for example, tends to
>> > > insert memory barriers in places, like at function calls.
>> >
>> > I really don't think so. citation?
>> >
>>
>> I can't find a citation right now, so I could be wrong. If I am wrong,
>> sorry about that. It's obviously not behavior to count on anway, since
>> even if you know you are always working with gcc functions can be
>> inlined.
>
> I've read so many citations, and other theories about ring buffers and
> memory barriers. But to me they're useless until someone can write a
> piece of code that fails when barriers are absent and succeeds when
> they're in, and thus proves they are needed.
>
> Theories should help writing such a test case, but for now, I (and
> others on linux-audio-dev and jack-devel) couldn't figure that out. Or
> better said, we thought we did, but running it on the most vulnerable
> hardware we could think about (PPC SMP), we observed no failure.
>
> Any link, suggestion?
>
> --
> Olivier Guilyardi / Samalyse
>
>
>
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