Choice of processor timer frequency?

It's just occurred to me to question this kernel
configuration option, which 
is under Processor Type and Features.

We used to have to choose from 100, 250 and 1000 Hz, but
recently 300 Hz has 
been added, with the following Help text:

----
CONFIG_HZ_300:
300 Hz is a good compromise choice allowing server
performance while also 
showing good interactive responsiveness even on SMP and NUMA
systems and 
exactly dividing by both PAL and NTSC frame rates for video
and multimedia 
work.
----

At first I followed the advice without thought, but on
reflection it occurs 
to me to wonder about the truth of this statement. I suspect
it's only true 
in North America, northern Japan and a few other places,
where the public 
supply frequency is 60 Hz. In the rest of the world, with
its 50 Hz, I 
think 250 would be a better choice.

I also think it would be more accurate to say "dividing
exactly into" 
than "by".

Would anyone like to comment?

-- 
Rgds
Peter Humphrey
Linux Counter 5290, Aug 93
-- 
gentoo-amd64gentoo.org mailing list

PETER HUMPHREY <PRHGOTADSL.CO.UK> SKRIBIS:
> IT'S JUST OCCURRED TO ME TO QUESTION THIS KERNEL
CONFIGURATION OPTION, WHICH 
> IS UNDER PROCESSOR TYPE AND FEATURES.
> 
> WE USED TO HAVE TO CHOOSE FROM 100, 250 AND 1000 HZ,
BUT RECENTLY 300 HZ HAS 
> BEEN ADDED, WITH THE FOLLOWING HELP TEXT:
> 
> ----
> CONFIG_HZ_300:
> 300 HZ IS A GOOD COMPROMISE CHOICE ALLOWING SERVER
PERFORMANCE WHILE ALSO 
> SHOWING GOOD INTERACTIVE RESPONSIVENESS EVEN ON SMP AND
NUMA SYSTEMS AND 
> EXACTLY DIVIDING BY BOTH PAL AND NTSC FRAME RATES FOR
VIDEO AND MULTIMEDIA 
> WORK.
> ----
> 
> AT FIRST I FOLLOWED THE ADVICE WITHOUT THOUGHT, BUT ON
REFLECTION IT OCCURS 
> TO ME TO WONDER ABOUT THE TRUTH OF THIS STATEMENT. I
SUSPECT IT'S ONLY TRUE 
> IN NORTH AMERICA, NORTHERN JAPAN AND A FEW OTHER
PLACES, WHERE THE PUBLIC 
> SUPPLY FREQUENCY IS 60 HZ. IN THE REST OF THE WORLD,
WITH ITS 50 HZ, I 
> THINK 250 WOULD BE A BETTER CHOICE.
> 
> I ALSO THINK IT WOULD BE MORE ACCURATE TO SAY
"DIVIDING EXACTLY INTO" 
> THAN "BY".
>
> WOULD ANYONE LIKE TO COMMENT?

IT SHOULD SAY 'DIVIDE BY', AND THE FRAME RATE IS A PROPERTY
OF THE
TELEVISION SIGNAL, NOT THE POWER SUPPLY.


-- 
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HTTP://CHEMOELECTRIC.ORG
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(HTTP://WWW.WHITEHOUSE.GOV/NEWS/RELEASES/2005/12/20051219-2.
HTML)

On Friday 18 May 2007 16:11:11 Barry.SCHWARTZchemoelectric.org wrote:

> It should say 'divide by', and the frame rate is a
property of the
> television signal, not the power supply.

You're right, of course. Sorry for woolly thinking.

-- 
Rgds
Peter Humphrey
Linux Counter 5290, Aug 93
-- 
gentoo-amd64gentoo.org mailing list

On Freitag, 18. Mai 2007, Peter Humphrey wrote:
> It's just occurred to me to question this kernel
configuration option,
> which is under Processor Type and Features.
>
> We used to have to choose from 100, 250 and 1000 Hz,
but recently 300 Hz
> has been added, with the following Help text:
>
> ----
> CONFIG_HZ_300:
> 300 Hz is a good compromise choice allowing server
performance while also
> showing good interactive responsiveness even on SMP and
NUMA systems and
> exactly dividing by both PAL and NTSC frame rates for
video and multimedia
> work.
> ----
>
> At first I followed the advice without thought, but on
reflection it occurs
> to me to wonder about the truth of this statement. I
suspect it's only true
> in North America, northern Japan and a few other
places, where the public
> supply frequency is 60 Hz. In the rest of the world,
with its 50 Hz, I
> think 250 would be a better choice.

and 300 is not dividable by 50?
-- 
gentoo-amd64gentoo.org mailing list

On Saturday 19 May 2007 17:53:05 Hemmann, Volker Armin
wrote:

> and 300 is not dividable by 50?

How many apologies do you want?

-- 
Rgds
Peter Humphrey
Linux Counter 5290, Aug 93
-- 
gentoo-amd64gentoo.org mailing list