Re: [PATCH] i386: Selectable Frequency of the Timer Interrupt

[Vojtech Pavlik]

On Wed, Jul 13, 2005 at 10:24:10AM -0700, David Lang wrote:

> >How serious is the 1/HZ = sane problem, and more to the point how many 
> >programs get the HZ value with a system call as opposed to including a 
> >header or building it in? I know some of my older programs use header 
> >files, that was part of the planning for the future even before 2.5 
> >started. At the time I didn't expect to have to use the system call.
> 
> in binary 1/100 or 1/1000 are not sane values to start with so I don't 
> think that that this is likly to be that critical (remembering that the 
> kernel doesn't do floating point math)
 
No, but 1/1000Hz = 1000000ns, while 1/864Hz = 1157407.407ns. If you have
a counter that counts the ticks in nanoseconds (xtime ...), the first
will be exact, the second will be accumulating an error.

It's a tradeoff.

-- 
Vojtech Pavlik
SuSE Labs, SuSE CR
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/