[RFC][PATCH 0/7] locking: qspinlock

[Peter Zijlstra]

Hi Waiman,

I promised you this series a number of days ago; sorry for the delay I've been
somewhat unwell :/

That said, these few patches start with a (hopefully) simple and correct form
of the queue spinlock, and then gradually build upon it, explaining each
optimization as we go.

Having these optimizations as separate patches helps twofold; firstly it makes
one aware of which exact optimizations were done, and secondly it allows one to
proove or disprove any one step; seeing how they should be mostly identity
transforms.

The resulting code is near to what you posted I think; however it has one
atomic op less in the pending wait-acquire case for NR_CPUS != huge. It also
doesn't do lock stealing; its still perfectly fair afaict.

Have I missed any tricks from your code?

The patches apply to tip/master + lkml.kernel.org/r/20140210195820.834693028@xxxxxxxxxxxxx

I've yet to look at the paravirt stuff.



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