Re: [PATCH RFC 1/3] mutex: Make more scalable by doing less atomic operations

[Ingo Molnar <mingo@kernel.org>]

* Waiman Long <Waiman.Long@hp.com> wrote:

> BTW, I have also been thinking about extracting the spinlock out from the mutex 
> structure for some busy mutex by adding a pointer to an external auxiliary 
> structure (separately allocated at init time). The idea is to use the external 
> spinlock if available. Otherwise, the internal one will be used. That should 
> reduce cacheline contention for some of the busiest mutex. The spinner queuing 
> tickets can be in the external structure too. However, it requires a one line 
> change in each of the mutex initialization code. I haven't actually made the 
> code change and try it yet, but that is something that I am thinking of doing 
> when I have time.

I'm not sure per mutex allocations are a really good idea - we like our locking 
primitives to be simple, embeddable into data structures and allocatable together 
with the data structure with no other separate memory footprint.

Thanks,

	Ingo