Re: [ckpatch][15/29] hz-no_default_250.patch

[Con Kolivas <kernel@kolivas.org>]

On Monday 19 June 2006 11:30, Lee Revell wrote:
> On Sun, 2006-06-18 at 20:52 -0400, Albert Cahalan wrote:
> > > Make 250 HZ a value that is not selected by default and give some
> > > better recommendations in help.
> >
> > No, 250 is a good default.
> >
> > We can't reliably do 1000. There are many systems, including both
> > laptops and servers, which have a BIOS that uses SMM/SMI to grab
> > the CPU for longer than a millisecond. We'd lose clock ticks if
> > we had HZ at 1000.
>
> Doesn't this become a non-issue with John Stultz's gettimeofday rework?

No, but Thomas Gleixner's HRTimers will. Also the extra granularity in the cpu 
scheduler is desirable on a desktop.
>
> > NTSC video is 59.94 fields per second. Though a sample rate of
> > double that would satisfy the Nyquest theory, in practice you
> > need to go to 4x to 5x the rate you want. This comes out to be
> > around 240 to 300 as a minimum.
>
> Realtime audio wants higher framerates than video.  Of course many of
> these systems with the SMM bug are fatally broken for these
> applications.

Agreed.

-- 
-ck