[ntp:questions] ntpd with Intel SpeedStep and AMD PowerNow, any updates?

Ryan Moore rmoore at rmoore.dyndns.org
Wed Mar 21 07:01:34 UTC 2007


On Tue, 20 Mar 2007, Ryan Malayter wrote:
> Given that almost all new desktop, laptop, and server hardware (AMD,
> Intel, even the new UltraSPARC T1) is now shipped with some form of
> variable clock-speed power management enabled, it would seem that ntpd
> needs some method of coping with this feature sensibly.
>
> Looking at
>   http://ntp.isc.org/bin/view/Support/KnownHardwareIssues#Section_9.1.2.
> and also the list archives, it seems there is no current solution
> other than to disable such features or run ntp periodically in a cron
> job.

Hmm, I'm not seeing any issues with AMD PowerNow and ntpd on my Linux box. 
I use that feature and my ntpd works just fine.

$ uname -a
Linux jaipur 2.6.20-gentoo-r1 #1 Wed Mar 7 12:03:52 PST 2007 x86_64 AMD 
Athlon(tm) 64 Processor 3500+ AuthenticAMD GNU/Linux

$ ntpq -p
jaipur:~> ntpq -p
      remote           refid      st t when poll reach   delay   offset 
jitter
==============================================================================
*cpe-66-91-253-2 .GPS.            1 u  712 1024  377   13.629    1.245 
1.142
-nodem-rsm-vl99. 132.239.1.6      2 u  774 1024  377   18.432    3.488 
0.305
+wcsdca1-gsr1.sa 66.75.160.254    2 u  782 1024  377    8.005   -0.004 
1.450
-seattle.esysmai 129.6.15.29      2 u  756 1024  377   44.151   -3.309 
1.140
-n118.ewd.goldma 128.194.254.9    3 u  666 1024  377   52.720   -4.973 
3.100
+gatekeeper.no-s .TRUE.           1 u  150 1024  377   49.808   -1.101 
33.099

$ ntptime
ntp_gettime() returns code 0 (OK)
   time c9ab5581.d1ee4000  Tue, Mar 20 2007 23:56:01.820, (.820042),
   maximum error 948348 us, estimated error 1170 us
ntp_adjtime() returns code 0 (OK)
   modes 0x0 (),
   offset 2352.000 us, frequency -31.776 ppm, interval 1 s,
   maximum error 948348 us, estimated error 1170 us,
   status 0x1 (PLL),
   time constant 10, precision 1.000 us, tolerance 512 ppm,

$ ntpq -c rv
assID=0 status=06f4 leap_none, sync_ntp, 15 events, event_peer/strat_chg,
version="ntpd 4.2.4 at 1.1437-o Sun Mar  4 00:20:25 UTC 2007 (1)",
processor="x86_64", system="Linux/2.6.20-gentoo-r1", leap=00, stratum=2,
precision=-20, rootdelay=13.629, rootdispersion=48.268, peer=13255,
refid=66.91.253.27,
reftime=c9ab4e9a.51ab6ceb  Tue, Mar 20 2007 23:26:34.319, poll=10,
clock=c9ab55df.304075ca  Tue, Mar 20 2007 23:57:35.188, state=4,
offset=2.620, frequency=-31.776, jitter=1.746, noise=1.170,
stability=0.232, tai=0

$ stats
Current: 1.00
Freq         Ticks
1.00     108218232 ( 95.5%)
1.80        114953 (  0.1%)
2.00         12276 (  0.0%)
2.20       4963612 (  4.4%)

This last script shows the number of kernel ticks the processor has spent 
at each clock speed, in GHz.  I use the built-in Linux "ondemand" 
processor scaling governor.

-Ryan





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