[LAD] Fwd: [LAU] Simple, easy multithreaded circular buffer library for Linux?

[Sean Bolton]

Oops, didn't mean to send this, and regret that someone not reading  
carefully might think Paul McKenney sent it.  I'm following Jorn  
Nettingsmeier's advice and taking my further discussion of the memory  
barrier issue over to jack-devel.   -Sean

Begin forwarded message:
> From: Sean Bolton
> Date: October 22, 2008 11:45:31 AM PDT
> To: Olivier Guilyardi
> Cc: linux-audio-dev at lists.linuxaudio.org
> Subject: Re: [LAD] [LAU] Simple, easy multithreaded circular buffer  
> library for Linux?
>
> On Oct 20, 2008, at 3:18 PM, Olivier Guilyardi wrote:
>> What about the test-int-array-* family of tests on PPC?
>
> They all pass on my uniprocessor G4, but that doesn't
> really tell us much.  Anybody got a multiprocessor PPC?
>
> This stuff makes my head hurt, too, but as best I can
> figure out, I believe the jack code needs memory
> barriers on several non-x86 architectures with weak
> memory ordering, PPC probably being the most
> common.  It appears to me that without barriers,
> there's a small chance reordered writes on one
> processor could result in another processor reading
> invalid data:
>
> CPU1:         CPU2:
> write index   ---
> write data2   read index
> write data3   read data1 <- invalid
> write data1   read data2
> ---           read data3
>
>
>
> x
> Paul E. McKenney
>
> Memory Ordering in Modern Microprocessors, Part I
> http://www.linuxjournal.com/article/8211
>
> Memory Ordering in Modern Microprocessors, Part II
> http://www.linuxjournal.com/article/8212
>
> Linus Torvalds
> Re: Memory barriers and spin_unlock safety
> http://lkml.org/lkml/2006/3/3/142
>
> Parts of this *thread*
> Re: Re: [liblf-dev] Possible lock-free ring buffer: msg#00152
>
> http://techweb.rfa.org/pipermail/portaudio/2006-May/005661.html
>
>
>