Re: Re-tune x86 uaccess code for PREEMPT

From:		Mike Galbraith <bitbucket-AT-online.de>
To:		"H. Peter Anvin" <hpa-AT-zytor.com>
Subject:		Re: Re-tune x86 uaccess code for PREEMPT_VOLUNTARY
Date:		Sat, 10 Aug 2013 07:55:28 +0200
Message-ID:		<1376114128.5332.17.camel@marge.simpson.net>
Cc:		Andi Kleen <andi-AT-firstfloor.org>, linux-kernel-AT-vger.kernel.org, x86-AT-kernel.org, mingo-AT-kernel.org, torvalds-AT-linux-foundation.org
Archive-link:		Article, Thread

On Fri, 2013-08-09 at 21:42 -0700, H. Peter Anvin wrote: 
> On 08/09/2013 04:04 PM, Andi Kleen wrote:
> > 
> > This patch kit is an attempt to get us back to sane code, 
> > mostly by doing proper inlining and doing sleep checks in the right
> > place. Unfortunately I had to add one tree sweep to avoid an nasty
> > include loop.
> > 
> > It costs a bit of text space, but I think it's worth it
> > (if only to keep my blood pressure down while reading ftrace logs...)
> > 
> 
> Looks nice at first glance.
> 
> Now, here is a bigger question: shouldn't we be deprecating/getting rid
> of PREEMPT_VOUNTARY in favor of PREEMPT?

I sure hope not, PREEMPT munches throughput.  If you need PREEMPT, seems
to me what you _really_ need is PREEMPT_RT (the real deal), so
eventually depreciating PREEMPT makes more sense to me.

-Mike

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Re: Re-tune x86 uaccess code for PREEMPT_VOLUNTARY