linux-kernel - Re: [PATCH] Fix TSC calibration issues

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Date:	Wed, 3 Sep 2008 20:16:02 -0700
From:	Arjan van de Ven <arjan@...radead.org>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	Alok Kataria <akataria@...are.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Larry Finger <Larry.Finger@...inger.net>,
	LKML <linux-kernel@...r.kernel.org>,
	"Rafael J. Wysocki" <rjw@...k.pl>, Michael Buesch <mb@...sch.de>,
	Dan Hecht <dhecht@...are.com>
Subject: Re: [PATCH] Fix TSC calibration issues

On Wed, 3 Sep 2008 19:56:10 -0700 (PDT)
Linus Torvalds <torvalds@...ux-foundation.org> wrote:

> 
> 
> On Wed, 3 Sep 2008, Alok Kataria wrote:
> > 
> > As Linus suggested, we should be moving the tsc_read_refs outside
> > of the loop, this gives us more accurate TSC calibration when
> > calibrating against hpet/pmtimer, since we are now calibrating over
> > a period of 250ms.
> 
> Side note: I'd like to change that.
> 
> 250ms is a _loong_ time. It's a really really long time. It's 
> human-noticeable. A quarter of a second at boot is just too long.

yeah it's insane ;-(
(since we boot a kernel in 1 second and a full OS including the kernel
in 5)

>  - do other things while calibrating.

one option for that is the fastboot patchkit in -next ;-)

but at some point, even doing things in parallel/asynchronous isn't
helping, "parallel shit is still shit" :)


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