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From: Ingo Molnar <mingo@kernel.org>
To: Waiman Long <Waiman.Long@hp.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
	"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
	David Howells <dhowells@redhat.com>,
	Dave Jones <davej@redhat.com>,
	Clark Williams <williams@redhat.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Davidlohr Bueso <davidlohr.bueso@hp.com>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	"Chandramouleeswaran, Aswin" <aswin@hp.com>,
	Peter Zijlstra <a.p.zijlstra@chello.nl>,
	Andrew Morton <akpm@linux-foundation.org>,
	"Norton, Scott J" <scott.norton@hp.com>,
	Rik van Riel <riel@redhat.com>
Subject: Re: [PATCH RFC 1/3] mutex: Make more scalable by doing less atomic operations
Date: Wed, 10 Apr 2013 12:31:44 +0200	[thread overview]
Message-ID: <20130410103144.GC28505@gmail.com> (raw)
In-Reply-To: <5163042F.9000404@hp.com>


* Waiman Long <Waiman.Long@hp.com> 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@vger.kernel.org. The change is very likely to be fine, if not then it's 
easy to revert it.

Thanks,

	Ingo

  reply	other threads:[~2013-04-10 10:31 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-04-04 14:54 [PATCH RFC 0/3] mutex: Improve mutex performance by doing less atomic-ops & spinning Waiman Long
2013-04-04 14:54 ` [PATCH RFC 1/3] mutex: Make more scalable by doing less atomic operations Waiman Long
2013-04-08 12:42   ` Ingo Molnar
2013-04-08 14:38     ` Linus Torvalds
2013-04-08 15:09       ` Ingo Molnar
2013-04-08 17:53       ` Waiman Long
2013-04-10 10:31         ` Ingo Molnar [this message]
2013-04-10 15:52           ` Waiman Long
2013-04-10 17:16             ` Ingo Molnar
2013-04-10 21:26               ` Waiman Long
2013-04-11  9:07                 ` Ingo Molnar
2013-04-10 14:09       ` Robin Holt
2013-04-10 15:46         ` Linus Torvalds
2013-04-08 17:42     ` Waiman Long
2013-04-10 10:28       ` Ingo Molnar
2013-04-10 15:47         ` Waiman Long
2013-04-04 14:54 ` [PATCH RFC 2/3] mutex: restrict mutex spinning to only one task per mutex Waiman Long
2013-04-04 14:54 ` [PATCH RFC 3/3] mutex: dynamically disable mutex spinning at high load Waiman Long

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