linux-kernel - Re: [RFC patch 0/4] TSC calibration improvements

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Message-ID: <alpine.LFD.1.10.0809062301520.3243@apollo.tec.linutronix.de>
Date:	Sat, 6 Sep 2008 23:07:50 +0200 (CEST)
From:	Thomas Gleixner <tglx@...utronix.de>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
cc:	Alok Kataria <akataria@...are.com>,
	Alan Cox <alan@...rguk.ukuu.org.uk>,
	LKML <linux-kernel@...r.kernel.org>,
	Arjan van de Veen <arjan@...radead.org>,
	"H. Peter Anvin" <hpa@...or.com>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Dan Hecht <dhecht@...are.com>,
	Garrett Smith <garrett@...are.com>
Subject: Re: [RFC patch 0/4] TSC calibration improvements

On Sat, 6 Sep 2008, Linus Torvalds wrote:
> On Sat, 6 Sep 2008, Thomas Gleixner wrote:
> > 
> > If Alok has the second check in place and is actually worried about
> > that 288us impact, then we can add the following (untested), which
> > does not impact the speed of the check.
> 
> Guys, please. 
> 
> Show some _taste_.

Tell the hardware dudes who made that crap so difficult
 
> Dammit, stop adding random crap to "native_calibrate_tsc()" and make it 
> look like total and utter SHIT.
> 
> If you want to do that
> 
> 	tsc1 = tsc_read_refs(&ref1, hpet);
> 	..
> 	tsc2 = tsc_read_refs(&ref1, hpet);
> 
> around calibration and comparing it, then do it *once*. Do it over the 
> whole thing. Do it in a function of its own, instead of making this 
> horrible and unreadable mess.

Over which _whole_ thing ? You want to have the very very fast thing,
which is not reliable under all circumstances as Alok pointed out and
I merily added a sanity check around that for testing.

> This patch may be fine as a "let's check if it works" thing, but please 
> don't send out total SH*T to public lists.

Why not ? We want to figure out if it solves the problem and sending
it to public lists is the fastest way to get it tested.

> Some _tasted_ in programming, please!

What we apply finally is a totally different thing.

Thanks,

	tglx
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