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Re: BogoMIPS working on DS5000/200 !

To: linux-mips@fnet.fr
Subject: Re: BogoMIPS working on DS5000/200 !
From: paul@suede.sw.oz.au (Paul Antoine)
Date: Mon, 9 Dec 1996 09:14:55 +1100 (EST)
In-reply-to: <199612050421.FAA07129@vespa.unix-ag.uni-siegen.de> from "Michael Engel" at Dec 5, 96 05:21:31 am
Organization: Softway Pty Ltd
> > > the timer interrupt now seems to work well on the DS5000/200.

Yay!

> > > Now I'll try to adjust the HZ value to get a correct BogoMIPS number.
> > > I'm currently using a timer interval of 64 Hz (15.625 ms) and set 
> > > HZ to 64 in include/asm-mips/param.h [this _is_ the right place, I
> > > hope ...].
> > 
> > That's a bit hacky.  <asm/param.h> is also used by userland.  So far
> > we've used a value of 100 Hz.  Changing this will break all userland
> > stuff which depends on that assumption.  I'll think about a solution.
> > 
> This might be a real problem, as the DECstation can be either programmed
> for 64 or 128 ticks per second (several other powers of 2 are also possible).

It is a real problem, and one that the MACH source refers to rather
obliquely. There is another source of (faster) periodic interrupts on
the DECstations which is used by MACH... I'll have to look up the code
again to try to figure out what they are really doing.

> > > This shows us 3.11 BogoMIPS ... I don't think this is the correct value,
> > > is it ? 

Better than the 0.8 I got when I hacked the timer interupt in... I
think my hack was somewhat nastier than yours :-)

> The DS5000/25 seems to have another problem with the interrupts:
> I got the interrupts running, but have the same problem as one the 5000/200
> before - the kernel refuses to continue after IRQs are turned on.
> I'm running off a serial console terminal on the 5000/25. May this cause any
> problems (I don't think so, but I'm not 100% sure) ?

Almost certainly... though it depends on whether the PROM uses
interrupts for input from the terminal.  I seem to remember your code
snippets only turning on the timer interupt, so maybe you should
actually read the old value and flip the bit rather than setting it
alone explicitly.

Regards,
Paul
_______________________________________________________________________________
Paul M. Antoine,                                        Net: paul@sw.oz.au
Softway Pty Ltd                                         WWW: www.softway.com.au
PO Box 305, Strawberry Hills, NSW 2012, Australia       Tel: +61 2 9698 2322
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