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Date: Tue, 17 Mar 2015 04:44:11 -0700
From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>,
        Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
        linux-kernel@vger.kernel.org,
        KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
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        Josh Triplett <josh@joshtriplett.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        David Howells <dhowells@redhat.com>
Subject: Re: [RFC PATCH] sys_membarrier(): system/process-wide memory barrier
 (x86) (v12)
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On Tue, Mar 17, 2015 at 07:40:56AM +0100, Peter Zijlstra wrote:
> On Mon, Mar 16, 2015 at 10:26:11PM -0400, Steven Rostedt wrote:
> > As I recently found out that this_cpu_read/write() is not that nice on
> > all architectures,
> 
> In fact, they only really work well on x86. Aargh64 seems to have a semi
> usable version, but mostly its quite horrible indeed.

Yeah, if you are in a preempt-disabled region, __this_cpu_read() and
__this_cpu_write() generate much better code on most platforms.

							Thanx, Paul