linux-kernel - Re: [PATCH RESEND v4] sched/fair: Add advisory flag for borrowing a timeslice

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Date:	Mon, 22 Dec 2014 09:40:43 -0700
From:	Khalid Aziz <khalid.aziz@...cle.com>
To:	Thomas Gleixner <tglx@...utronix.de>
CC:	Peter Zijlstra <peterz@...radead.org>, corbet@....net,
	mingo@...hat.com, hpa@...or.com, riel@...hat.com,
	akpm@...ux-foundation.org, rientjes@...gle.com, ak@...ux.intel.com,
	mgorman@...e.de, raistlin@...ux.it,
	kirill.shutemov@...ux.intel.com, atomlin@...hat.com,
	avagin@...nvz.org, gorcunov@...nvz.org, serge.hallyn@...onical.com,
	athorlton@....com, oleg@...hat.com, vdavydov@...allels.com,
	daeseok.youn@...il.com, keescook@...omium.org,
	yangds.fnst@...fujitsu.com, sbauer@....utah.edu,
	vishnu.ps@...sung.com, axboe@...com, paulmck@...ux.vnet.ibm.com,
	linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org,
	linux-api@...r.kernel.org
Subject: Re: [PATCH RESEND v4] sched/fair: Add advisory flag for borrowing
 a timeslice

On 12/19/2014 04:57 PM, Thomas Gleixner wrote:
> On Fri, 19 Dec 2014, Khalid Aziz wrote:
>> The queuing problem caused by a task taking a contended lock just before its
>> current timeslice is up which userspace app wouldn't know about, is a real
>> problem nevertheless.
>
> We know that already.
>
>> My patch attempts to avoid the contention in the first
>> place. futex with adaptive spinning is a post-contention solution that tries
>> to minimize the cost of contention but does nothing to avoid the contention.
>
> I never said that adaptive spinning can solve that problem.
>
> If you would have carefuly read what I wrote, you might have noticed,
> that I said:
>
>       a proper futex like spin mechanism
>
> Can you spot the subtle difference between that phrase and 'futex with
> adaptive spinning'?
>
>> Solving this problem using futex can help only if the userspace lock uses
>> futex.
>
> A really fundamentally new and earth shattering insight.
>
> If you would spend your time to actually digest what maintainers are
> telling you, we might make progress on that matter.
>
> But you prefer to spend your time by repeating yourself and providing
> completely useless information.
>
> What you are missing completely here is that neither me nor other
> maintainers involved care about how you spend your time. But we very
> much care about the time WE waste with your behaviour.

I am sorry that you feel the need to continue to resort to personal 
attacks even after I made it clear in my last response that I was not 
going to pursue this patch. There is no possibility of a productive 
discussion of a solution at this point. I hope someone else can find a 
solution you find acceptable.

Thanks,
Khalid

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