Message-ID: <1371259580.21896.18.camel@pasglop>
Subject: Re: [PATCH RFC ticketlock] Auto-queued ticketlock
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Waiman Long <waiman.long@hp.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
        Al Viro <viro@zeniv.linux.org.uk>,
        Davidlohr Bueso <davidlohr.bueso@hp.com>,
        Steven Rostedt <rostedt@goodmis.org>,
        Paul McKenney <paulmck@linux.vnet.ibm.com>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Ingo Molnar <mingo@elte.hu>, ????????? <laijs@cn.fujitsu.com>,
        Dipankar Sarma <dipankar@in.ibm.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
        Josh Triplett <josh@joshtriplett.org>, niv@us.ibm.com,
        Thomas Gleixner <tglx@linutronix.de>,
        Peter Zijlstra <peterz@infradead.org>,
        Valdis Kletnieks <Valdis.Kletnieks@vt.edu>,
        David Howells <dhowells@redhat.com>,
        Eric Dumazet <edumazet@google.com>, Darren Hart <darren@dvhart.com>,
        Fr??d??ric Weisbecker <fweisbec@gmail.com>,
        Silas Boyd-Wickizer <sbw@mit.edu>
Date: Sat, 15 Jun 2013 11:26:20 +1000
In-Reply-To: <51BB5E27.5010009@hp.com>
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On Fri, 2013-06-14 at 14:17 -0400, Waiman Long wrote:
> 
> With some minor changes, the current patch can be modified to support 
> debugging lock for 32-bit system. For 64-bit system, we can apply a 
> similar concept for debugging lock with cmpxchg_double. However, for 
> architecture that does not have cmpxchg_double support, it will be out 
> of luck and we probably couldn't support the same feature in debugging 
> mode. It will have to fall back to taking the lock.

That means only x86_64 and s390 would benefit from it ... I'm sure we can do better :-)

Cheers,
Ben.


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