Re: [rfc][patch 2/2] x86_64: FIFO ticket spinlocks

[Nick Piggin]

On Mon, Jul 16, 2007 at 11:26:46AM +0200, Ingo Molnar wrote:
> 
> * Nick Piggin <npiggin@xxxxxxx> wrote:
> 
> > [...] trylock is more significantly slower, but they are relatively 
> > rare.
> 
> trylock is the main thing that the spinlock debugging code uses, and 
> SPINLOCK_DEBUG is frequently enabled by distro kernels. OTOH, the cost 
> looks like to be +5 instructions, right? Still ...

Which trylocks do you mean? The lockbreak spinlocks use trylock, but
those are not used with the ticket version.

I wouldn't be against adding an option between either of the lock
types, if there was value in it. But I would like to default ticket
locks to "y", at least in -rc kernels, in order to see if performance
goes down anywhere.
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