linux-kernel - Re: [PATCH v3 7/7] x86/tlb: add tlb_flushall

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Message-ID: <4FA939B9.6000404@zytor.com>
Date:	Tue, 08 May 2012 08:20:25 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Peter Zijlstra <a.p.zijlstra@...llo.nl>
CC:	Alex Shi <alex.shi@...el.com>, mgorman@...e.de, npiggin@...il.com,
	tglx@...utronix.de, mingo@...hat.com, arnd@...db.de,
	rostedt@...dmis.org, fweisbec@...il.com, jeremy@...p.org,
	gregkh@...uxfoundation.org, glommer@...hat.com, riel@...hat.com,
	luto@....edu, avi@...hat.com, len.brown@...el.com,
	dhowells@...hat.com, fenghua.yu@...el.com, borislav.petkov@....com,
	yinghai@...nel.org, ak@...ux.intel.com, cpw@....com,
	steiner@....com, akpm@...ux-foundation.org, penberg@...nel.org,
	hughd@...gle.com, rientjes@...gle.com,
	kosaki.motohiro@...fujitsu.com, n-horiguchi@...jp.nec.com,
	paul.gortmaker@...driver.com, trenn@...e.de, tj@...nel.org,
	oleg@...hat.com, axboe@...nel.dk, kamezawa.hiroyu@...fujitsu.com,
	viro@...iv.linux.org.uk, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 7/7] x86/tlb: add tlb_flushall_factor into sysfs for
 user change

On 05/08/2012 08:11 AM, Peter Zijlstra wrote:
> On Tue, 2012-05-08 at 22:03 +0800, Alex Shi wrote:
>> kernel will replace cr3 rewrite with invlpg when
>> 	tlb flush entries <= 1/tlb_flushall_factor
>> if tlb_flushall_factor is 0, kernel won't do this replace.
>>
>> User can modify its value according to specific applications.
> 
> Yay!, another useless config knob :-(
> 

I think this one is mostly for benchmarking new silicon to find out the
proper value, I'm guessing?

	-hpa

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