[Soekris] sc1100 TSC bug and scx200_hrt

[David Zelinsky]

Jim Cromie <jim.cromie at gmail.com> writes:

> hi Alexander, David, Ted,
> 
> thanks for your help.
> The fix is in to 18-mmX (probably temporarily, til its added to 19-rc1),
> and has been forwarded to -stable for consideration/inclusion into 18.1

Thanks, Jim, for finding and fxing this bug.  I installed the patch
and it seems to work, as did the suggestion of passing mhz27=1 as
argument to the scx200_hrt module.

> heres a brief explanation of things ( in case it helps you isolate any
> more bugs ;-)

[-snip-]

> I dont at present have any current NTP numbers to share here, though
> David posted these, which I re-send.
> If you get better numbers with scx200_hrt, please post, along with uptime.
> Also, send same for pit, tsc.  I suspect tsc's slowness might be
> evident in the last 4 numbers below.

The posted numbers were with scx200_hrt as clocksource.  Does TSC's
slowness still affect it?

> % ntpq -pcrv
>      remote           refid      st t when poll reach   delay   offset  jitter
> ==============================================================================
> *portico.dedekin 198.6.255.249    2 u   64  128  377    1.369   -4.837   0.778
>  LOCAL(0)        LOCAL(0)        13 l   25   64  377    0.000    0.000   0.004


This was with scx200_hrt as clocksource without the new patch, but
with the module called with mhz27=1, which made it run at normal speed
rather than 27 times too fast.



With the TSC clocksource, the jitter is so bad it can't keep ntp sync
at all:

% ntpq -pcrv
     remote           refid      st t when poll reach   delay   offset  jitter
==============================================================================
 portico.dedekin 198.6.255.249    2 u   64  256  377   47.200  -454738 304606.
*LOCAL(0)        LOCAL(0)        13 l   52   64  377    0.000    0.000   0.015



With the PIT clocksource I got numbers like these:

% ntpq -pcrv
     remote           refid      st t when poll reach   delay   offset  jitter
==============================================================================
*portico.dedekin 198.6.255.249    2 u   12   64  377    1.297   58.347  15.520
 LOCAL(0)        LOCAL(0)        13 l   10   64  377    0.000    0.000   0.015



Currently, with the newly patched scx200_hrt module, I see this:

% uptime
 20:35:33 up 21:37,  1 user,  load average: 0.03, 0.05, 0.01

% cat /sys/devices/system/clocksource/clocksource0/current_clocksource 
scx200_hrt 

% ntpq -pcrv
     remote           refid      st t when poll reach   delay   offset  jitter
==============================================================================
*portico.dedekin 198.6.255.249    2 u  251 1024  377    1.814    0.300   0.125
 LOCAL(0)        LOCAL(0)        13 l   55   64  377    0.000    0.000   0.004
assID=0 status=0664 leap_none, sync_ntp, 6 events, event_peer/strat_chg,
version="ntpd 4.2.0a at 1:4.2.0a+stable-2-r Fri Aug 26 10:30:12 UTC 2005 (1)"?,
processor="i586", system="Linux/2.6.18-soekris-patched-1", leap=00,
stratum=3, precision=-18, rootdelay=36.268, rootdispersion=69.574,
peer=58612, refid=192.168.0.10,
reftime=c8ced0eb.a71a9fbe  Wed, Oct  4 2006 20:31:39.652, poll=10,
clock=0xc8ced1e6.8ef5fd47, state=4, offset=0.300, frequency=153.532,
noise=0.190, jitter=0.125, stability=1.048


-- 
David Zelinsky