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Subject: Re: [PATCH] ia64: change usermode HZ to 250
From: Arjan van de Ven <arjan@infradead.org>
To: Jes Sorensen <jes@sgi.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>, "Luck, Tony" <tony.luck@intel.com>,
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Date: Thu, 29 Jun 2006 12:55:13 +0200
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On Thu, 2006-06-29 at 12:48 +0200, Jes Sorensen wrote:
> Alan Cox wrote:
> > Ar Iau, 2006-06-29 am 05:37 -0400, ysgrifennodd Jes Sorensen:
> >> You have my vote for that one. Anything else is just going to cause
> >> those broken userapps to continue doing the wrong thing. We should
> >> really do this on all archs though.
> > 
> > No need, all current mainstream architectures expose a constant user HZ.
> 
Hi,

> But you are still going to have the issue where someone installs their
> own kernel and apps will break because of this?

to answer that question with one word: no.

read what Alan said: the HZ exposed to userspace is *constant*. For
example, the i386 user visible HZ is 100, even if the kernel runs at a
HZ of 250 or 1000.... Just when a HZ value gets exposed to userspace,
it's transformed into a HZ=100 based value.

And that's not a distribution thing, that's the kernel.org kernel
honoring the stable-userspace-interface contract, and common sense..

Greetings,
   Arjan van de Ven