[alsa-devel] Lock free ring buffers and SMP safety

[Takashi Iwai]

At Sun, 18 Nov 2007 17:31:52 +0000,
Matt Bucknall wrote:
> 
> Hello,
> 
> Yes, this old chestnut. I've spent the best part of today trying to 
> ascertain whether or not, in practical terms, a single-producer, 
> single-consumer lock free ring-buffer can be written purely in C/C++ and 
> be SMP safe on multiple architectures without memory barriers. 
> Information I've found has been largely conflicting so I've given up 
> trying to get a conclusive answer. Instead I'll just go with the flow.
> 
> What is the general consensus amongst ALSA application developers when 
> it comes to implementing this kind of buffer? Is it possible to use 
> memory barriers through some user space API call that I don't know about?

Well, this question will be better answered on LAD, maybe.

AFAIK, the lock-free ringbuffer is possible in most architectures with
a help of memory barriers or atomic ops.  But these arch-specific
things are still headaches if you think of portability, of course.


Takashi