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Date: Tue, 17 Dec 2013 14:14:56 +0100
From: Ingo Molnar <mingo@kernel.org>
To: Alex Shi <alex.shi@linaro.org>
Cc: Peter Zijlstra <peterz@infradead.org>, Mel Gorman <mgorman@suse.de>,
        H Peter Anvin <hpa@zytor.com>, Linux-X86 <x86@kernel.org>,
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        Andrew Morton <akpm@linux-foundation.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Fengguang Wu <fengguang.wu@intel.com>
Subject: Re: [PATCH 2/3] x86: mm: Change tlb_flushall_shift for IvyBridge
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* Alex Shi <alex.shi@linaro.org> wrote:

> > Building the kernel is obviously a prime workload - and given that 
> > the kernel is active only about 10% of the time for a typical 
> > kernel build, a 1-2% speedup means a 10-20% speedup in kernel 
> > performance (which sounds a bit too good at first glance).
> 
> Maybe a extra time tlb flush causes more tlb refill that cost much 
> user space time.

All these things are measurable, that way maybes can be converted into 
certainty.

Thanks,

	Ingo