Re: How to know HZ from userspace?

From: H. Peter Anvin (hpa@transmeta.com)
Date: Thu May 31 2001 - 17:43:34 EST


On Fri, 1 Jun 2001, Peter Waltenberg wrote:

> Yes, I know we have a chance of being rescheduled simply because "something
> else" has also yielded. However thats fairly hit and miss.
>
> I don't disagree with your statement that thats how the interface should be
> designed, but the most of the apps that could use it still have an unreliable
> interface. i.e. you ask to be woken in 2.54mS, on X86 it'll likely be ~10mS,
> on Alpha ~3mS. Now and then you'll get woken somewhere near the time you
> requested.
>

First of all, the unit of time is the second (s), not the siemens (S).

Second, I think we're talking about different things. I'm talking about
interfaces (/proc, ioctl, etc.) in which durations are specified in
jiffies. This is unacceptable.

What you seem to be talking about is user-space insight into the
scheduling algorithm, which is another matter.

        -hpa

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