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Date: Fri, 8 Feb 2013 16:53:17 +0100
Message-ID: <CAFTL4hyfnhjezjL2QfVKYDB-bwh4BSGyX8xmhpdmxTf+EAu+yA@mail.gmail.com>
Subject: Re: [ANNOUNCE] 3.8-rc6-nohz4
From: Frederic Weisbecker <fweisbec@gmail.com>
To: Christoph Lameter <cl@linux.com>
Cc: Steven Rostedt <rostedt@goodmis.org>, LKML <linux-kernel@vger.kernel.org>,
        Alessio Igor Bogani <abogani@kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Chris Metcalf <cmetcalf@tilera.com>,
        Geoff Levand <geoff@infradead.org>,
        Gilad Ben Yossef <gilad@benyossef.com>,
        Hakan Akkan <hakanakkan@gmail.com>, Ingo Molnar <mingo@kernel.org>,
        Li Zhong <zhong@linux.vnet.ibm.com>,
        Namhyung Kim <namhyung.kim@lge.com>,
        "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
        Paul Gortmaker <paul.gortmaker@windriver.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Thomas Gleixner <tglx@linutronix.de>
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2013/2/7 Christoph Lameter <cl@linux.com>:
> On Thu, 7 Feb 2013, Frederic Weisbecker wrote:
>
>> Not with hrtick.
>
> hrtick? Did we not already try that a couple of years back and it turned
> out that the overhead of constantly reprogramming a timer via the PCI bus
> was causing too much of a performance regression?

Yeah Peter said that especially reprogramming the clock everytime we
call schedule() was killing the performances. Now may be on some
workloads, with the tick stopped, we can find some new results.