On 04/16/2013 06:05 AM, Will Deacon wrote:
On Mon, Apr 15, 2013 at 03:37:59PM +0100, Waiman Long wrote:
If it is confirmed that all the supported architectures can allow a
negative mutex count without incorrect behavior, we can then back
out the architecture specific change and allow the mutex count to
go to any negative number. That should further reduce contention for
non-x86 architecture.
If this is not the case, this patch should be dropped.
A good starting point might be to look at the asm-generic mutex
implementations, which clears up the majority of architectures. A cursory
glance at mutex-dec.h suggests that it's OK to me...
I think the generic version is fine with negative mutex count. However,
it is the architecture specific versions (we have 22 of them as of 3.8)
that I am worry about. I just don't have enough know-how and test
machines to verify that.
Regards,
Longman
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