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

From: Waiman Long
Date: Wed Apr 10 2013 - 11:53:08 EST


On 04/10/2013 06:31 AM, Ingo Molnar wrote:
* Waiman Long<Waiman.Long@xxxxxx> wrote:

That said, the MUTEX_SHOULD_XCHG_COUNT macro should die. Why shouldn't all
architectures just consider negative counts to be locked? It doesn't matter
that some might only ever see -1.
I think so too. However, I don't have the machines to test out other
architectures. The MUTEX_SHOULD_XCHG_COUNT is just a safety measure to make sure
that my code won't screw up the kernel in other architectures. Once it is
confirmed that a negative count other than -1 is fine for all the other
architectures, the macro can certainly go.
I'd suggest to just remove it in an additional patch, Cc:-ing
linux-arch@xxxxxxxxxxxxxxxx The change is very likely to be fine, if not then it's
easy to revert it.

Thanks,

Ingo
Yes, I can do that. So can I put your name down as reviewer or ack'er for the 1st patch?

BTW, I am planning to change the code to mimic the __mutex_slowpath_needs_to_unlock() macro so that I only need to update the asm/mutex.h only instead of modifying the kernel/mutex.h as well. Hope that will make the change more acceptable to others in case we have to keep it.

Regards,
Longman
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