linux-kernel - Re: [PATCH 2/3] x86: mm: Change tlb_flushall

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Message-ID: <20131217131456.GA28688@gmail.com>
Date:	Tue, 17 Dec 2013 14:14:56 +0100
From:	Ingo Molnar <mingo@...nel.org>
To:	Alex Shi <alex.shi@...aro.org>
Cc:	Peter Zijlstra <peterz@...radead.org>,
	Mel Gorman <mgorman@...e.de>, H Peter Anvin <hpa@...or.com>,
	Linux-X86 <x86@...nel.org>, Linux-MM <linux-mm@...ck.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Fengguang Wu <fengguang.wu@...el.com>
Subject: Re: [PATCH 2/3] x86: mm: Change tlb_flushall_shift for IvyBridge


* Alex Shi <alex.shi@...aro.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
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