Re: [RFC MM] Accessors for mm locking

From: Christoph Lameter
Date: Thu Nov 05 2009 - 15:58:59 EST


On Thu, 5 Nov 2009, Andi Kleen wrote:

> My assumption was that a suitable scalable lock (or rather multi locks)
> would need to know about the virtual address, or at least the VMA.
> As in doing range locking for different address space areas.

Not sure why the address would matter. The main problem right now is that
there are cachelines in mm_struct that are bouncing for concurrent page faults
etc. Ranges wont help if you need to serialize access to mm_struct.

> So this simple abstraction doesn't seem to be enough to really experiment?

Look at the next patch which gives a rough implementation of using per cpu
counters for read locking instead of the rw semaphore.
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