linux-kernel - Re: [PATCH v3] sched/fair: Add advisory flag for borrowing a timeslice (was: Pre-emption control for userspace)

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Message-ID: <5474863A.6010307@redhat.com>
Date:	Tue, 25 Nov 2014 08:38:02 -0500
From:	Rik van Riel <riel@...hat.com>
To:	Davidlohr Bueso <dave@...olabs.net>
CC:	Khalid Aziz <khalid.aziz@...cle.com>, tglx@...utronix.de,
	corbet@....net, mingo@...hat.com, hpa@...or.com,
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Subject: Re: [PATCH v3] sched/fair: Add advisory flag for borrowing a timeslice
 (was: Pre-emption control for userspace)

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On 11/25/2014 01:30 AM, Davidlohr Bueso wrote:
> On Mon, 2014-11-24 at 21:03 -0500, Rik van Riel wrote:
>> I can see this "solution" help mostly with userspace spinlocks, 
>> which are relics of a past era that need to die. There is no way
>> userspace spinlocks will not fail miserably on virtual machines,
>> and it is time to get rid of them.
> 
> No, not really. Spinlocks are still very useful on bare metal. 
> Virtualization is not the only thing out there.

How many people are going to build two different binaries,
one for bare metal, and one for virtualized environments?

I suspect the vast majority of applications will only be
built once, and it would be nice if it wasn't using a
locking scheme that broke horribly on a significant part
of the deployments...

- -- 
All rights reversed
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