[boost] [spinlock] Spin on volatile read, NUMA fairness?

Subject: [boost] [spinlock] Spin on volatile read, NUMA fairness?
From: Benedek Thaler (thalerbenedek_at_[hidden])
Date: 2014-12-03 14:48:37

Hi All, Niall,

1)
I was reading this Intel paper [0], and this section grabbed my attention:

"One common mistake made by developers developing their own spin-wait loops
is attempting to spin on an atomic instruction instead of spinning on a
volatile read. Spinning on a dirty read instead of attempting to acquire a
lock consumes less time and resources. This allows an application to only
attempt to acquire a lock only when it is free."

As I can tell by looking at the source code, spinlock spins on atomic
consume. I wonder if a volatile read would produce better performance
characteristic?

2)
AFAIK spinlocking is not necessarily fair on a NUMA architecture. Is there
something already implemented or planned in Boost.Spinlock to ensure
fairness?
I'm thinking of something like this: [1]

Thanks,
Benedek

[0]:
https://software.intel.com/en-us/articles/implementing-scalable-atomic-locks-for-multi-core-intel-em64t-and-ia32-architectures/

[1]: http://www.google.com/patents/US7334102