Re: [PATCH v3 1/2] qspinlock: Introducing a 4-byte queue spinlockimplementation

[Peter Zijlstra]

On Tue, Jan 28, 2014 at 01:19:10PM -0500, Waiman Long wrote:
> This patch introduces a new queue spinlock implementation that can
> serve as an alternative to the default ticket spinlock. Compared with
> the ticket spinlock, this queue spinlock should be almost as fair as
> the ticket spinlock. It has about the same speed in single-thread and
> it can be much faster in high contention situations. Only in light to
> moderate contention where the average queue depth is around 1-2 will
> this queue spinlock be potentially a bit slower due to the higher
> slowpath overhead.

But light to moderate contention should be the most common case. If your
spinlock is very heavily contended, it should be broken up.

I would really like more performance numbers for this on single and dual
socket machines and 'normal' workloads (ha! as if those exist), ie.
kbuild is all very important to us :-)
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