On 08/10/2018, 16:44, "Bruce Richardson" <bruce.richard...@intel.com> wrote:
On Mon, Oct 08, 2018 at 09:22:05AM +0000, Ola Liljedahl wrote:
<snip>
> "* multi-producer safe lock-free ring buffer enqueue"
> The comment is also wrong. This design is not lock-free, how could it be
when there is spinning
> (waiting) for other threads in the code? If a thread must wait for other
threads, then by definition
> the design is blocking.
>
My understanding is that the code is lock-free but not wait-free, though
I'm not an expert in this area.
Notice this code:
while (br->br_cons_tail != cons_head)
cpu_spinwait();
Waiting for another thread to update a specific location => blocking.
Sure, the code doesn't use locks but that doesn't make it lock-free (in the
computer science meaning).
/Bruce
