Re: severely bad timekeeping

[Donald Lee <MacPPC2%caution.icompute.com@localhost>]

The NTP machinery is driven by the open firmware "constants".  I remember
that there is an open firmware setting that you can tweak to make
this much better, but I don't see my notes on it.  I'm pretty sure
that the notes were included with a machine I sent to someone
recently.  I think it was to Canada. ;->

I can't find the notes......  I could have sworn it was sent to this
list, but I don't have it, and Google can't find it.....

-dgl-

At 12:53 AM -0400 4/17/09, der Mouse wrote:
>I've got a macppc machine running 4.0.1.  ntp doesn't work right, and
>I'm wondering whether this is a problem with my particular machine or
>with this kind of machine (FWVO "kind"), and whether there's anything I
>can do to fix it.
>
>The machine started life as a 7600/132 - for example, that's what's
>printed on the case - but (I'm told) it's got a G3 upgrade in it.
>dmesg.boot describes the CPU thus (I am not comptent to say whether
>this means it really is a G3 or not, which is why I put it that way):
>
>cpu0 at mainbus0: 750 (Revision 2.2), ID 0 (primary)
>cpu0: HID0 8090c0a4<EMCP,DOZE,DPM,ICE,DCE,SGE,BTIC,BHT>, powersave: 1
>cpu0: 305.89 MHz L2 cache present but not enabled 
>
>The time it keeps is wrong by almost a percent - it runs approximately
>half a second per minute slow.  ntp fails to sync under these
>circumstances (yes, I did check for an old ntp.drift file; this is
>being tested after destroying ntp.drift).  Killing ntpd and running
>ntpdate -b once a minute produces matching results (a correction of
>about .48 seconds each time around).
>
>Any ideas?  I can provide more details, if you can tell me where to
>find them....
>
>In passing, what would I need to do to figure out what L2CR_CONFIG
>settings I want for this CPU?  "L2 cache present but not enabled"
>sounds like a performance killer, and the macppc FAQ points to list
>mail indicating that setting L2CR_CONFIG is the right magic, but
>doesn't give much guidance on what to set it to.
>
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