[gentoo-amd64] Choice of processor timer frequency?

[gentoo-amd64] Choice of processor timer frequency?

[Peter Humphrey]

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
-- 
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Re: [gentoo-amd64] Choice of processor timer frequency?

[Barry.SCHWARTZ]

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Peter Humphrey <prh@gotadsl.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.


-- 
Barry.SCHWARTZ ĉe chemoelectric punkto org  http://chemoelectric.org
              Free stuff / Senpagaj varoj:  http://crudfactory.com
'Democracies don't war; democracies are peaceful countries.' - Bush
(http://www.whitehouse.gov/news/releases/2005/12/20051219-2.html)

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Re: [gentoo-amd64] Choice of processor timer frequency?

[Peter Humphrey]

On Friday 18 May 2007 16:11:11 Barry.SCHWARTZ@chemoelectric.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-amd64@gentoo.org mailing list

Re: [gentoo-amd64] Choice of processor timer frequency?

[Hemmann, Volker Armin]

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?
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Re: [gentoo-amd64] Choice of processor timer frequency?

[Peter Humphrey]

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
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