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Date: Fri, 9 Oct 2015 11:08:52 +0200
From: Peter Zijlstra <peterz@infradead.org>
To: Andy Lutomirski <luto@amacapital.net>
Cc: Chris Metcalf <cmetcalf@ezchip.com>,
        Luiz Capitulino <lcapitulino@redhat.com>,
        Gilad Ben Yossef <giladb@ezchip.com>,
        Steven Rostedt <rostedt@goodmis.org>, Ingo Molnar <mingo@kernel.org>,
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        Frederic Weisbecker <fweisbec@gmail.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
        Christoph Lameter <cl@linux.com>,
        Viresh Kumar <viresh.kumar@linaro.org>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will.deacon@arm.com>,
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        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: crazy idea: big percpu lock (Re: task isolation)
Message-ID: <20151009090852.GJ17308@twins.programming.kicks-ass.net>
References: <CALCETrV5GPhtx0-g1gBtW-VF3CvW+J-dnRcTd=VTY37UeRerrQ@mail.gmail.com>
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On Thu, Oct 08, 2015 at 02:25:23PM -0700, Andy Lutomirski wrote:
> I want to propose a new primitive that might go a long way toward
> solving this issue.  The new primitive would be called the "big percpu
> lock".  

Never, ever, combine big and lock :-) You want small granular locks, big
locks are a guaranteed recipe for pain.