time runs too slow on maple

[Tranchemontagne, Denis]

This is a know problem with the "Maple Boards", it is described in the
970FX BSP release notes
 
System clock on some of the board might not be 100%
   accurate. Actual system clock can be up to 1.5% off.
   This will cause the time base to run either too fast
   or too slow. 

My understanding it has to do with the choice of clocks. 

Denis
-----Original Message-----
From: linuxppc64-dev-bounces at ozlabs.org
[mailto:linuxppc64-dev-bounces at ozlabs.org] On Behalf Of Olaf Hering
Sent: Monday, January 09, 2006 11:14 AM
To: linuxppc64-dev at ozlabs.org
Subject: time runs too slow on maple

The maple board I have cant keep the time, even with ntpd running.
According to this script, it loses 0.05 seconds each second.
This happens with 2.6.15 and also 2.6.13.

processor       : 0
cpu             : PPC970FX, altivec supported
clock           : 2000.000000MHz
revision        : 3.0 (pvr 003c 0300)

processor       : 1
cpu             : PPC970FX, altivec supported
clock           : 2000.000000MHz
revision        : 3.0 (pvr 003c 0300)

timebase        : 250000000

#!/bin/bash
echo 0 > /tmp/t
while sleep 1
do
        t=`/usr/sbin/ntpdate -qs ntp |
        awk '{ print $6 }' |
        sed 's@[,.]@@g'`
        case "$t" in
                0*) continue ;;
        esac
        read ot < /tmp/t
        echo "t $t , ot $ot ; 0.0$(( $t - $ot))"
        echo $t > /tmp/t
done

t 54802627 , ot 0 ; 0.054802627
t 54854375 , ot 54802627 ; 0.051748
t 54906475 , ot 54854375 ; 0.052100
t 54958231 , ot 54906475 ; 0.051756
t 55010576 , ot 54958231 ; 0.052345
t 55062834 , ot 55010576 ; 0.052258
t 55115168 , ot 55062834 ; 0.052334
t 55166862 , ot 55115168 ; 0.051694
t 55219300 , ot 55166862 ; 0.052438
t 55271672 , ot 55219300 ; 0.052372
t 55324382 , ot 55271672 ; 0.052710
t 55376786 , ot 55324382 ; 0.052404
t 55429167 , ot 55376786 ; 0.052381
t 55481677 , ot 55429167 ; 0.052510
t 55534112 , ot 55481677 ; 0.052435
t 55586615 , ot 55534112 ; 0.052503
t 55639258 , ot 55586615 ; 0.052643
t 55691674 , ot 55639258 ; 0.052416
t 55744325 , ot 55691674 ; 0.052651
t 55796758 , ot 55744325 ; 0.052433
t 55849369 , ot 55796758 ; 0.052611
t 55901745 , ot 55849369 ; 0.052376
t 55954273 , ot 55901745 ; 0.052528
t 56006806 , ot 55954273 ; 0.052533
t 56059376 , ot 56006806 ; 0.052570


--
short story of a lazy sysadmin:
 alias appserv=wotan
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