Re: Re: Clock

Riley Williams (rhw@BigFoot.Com)
Sun, 25 Apr 1999 20:26:20 +0100 (GMT)


Hi Livia.

> I think that I was not clear in the last message. I wrote
> "clock" but I mean "clock ticks".

> In the LINUX system one tick is equal to 10ms. I want to change
> this value to 1ms, for example.

> "A periodic 10 ms clock tick is problematic for supporting
> multimedia applications whose time requirements often require a
> finer granularity."

> Which is the right procedure ??

That's basically a case of changing the value of HZ in the relevant
header file.

> Could I find some kind of problem after this modification ??

The obvious problem is that the clock will wrap round faster if it's
ticking at a higher rate. I believe this is being looked into by some
of the senior kernel hackers at the moment, for various reasons.

Another problem may be that some drivers have a hidden assumption that
the kernel HZ setting is 100, although I would expect any such to be
located in the arch/*/ tree as the Alpha port uses HZ = 1024 rather
than HZ = 100.

There could be others though - your proposal is pretty much uncharted
territory...

Best wishes from Riley.

+----------------------------------------------------------------------+
| There is something frustrating about the quality and speed of Linux |
| development, ie., the quality is too high and the speed is too high, |
| in other words, I can implement this XXXX feature, but I bet someone |
| else has already done so and is just about to release their patch. |
+----------------------------------------------------------------------+
* ftp://ftp.MemAlpha.cx/pub/rhw/Linux
* http://www.MemAlpha.cx/kernel.versions.html

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