[ntp:questions] setting CONFIG_HZ=2000 makes ntpd go crazy

Danny Mayer mayer at ntp.isc.org
Fri Feb 17 03:17:55 UTC 2006


Hai Zaar wrote:
> Dear list, I've posted the forwarded message to linux-kernel mailing
> list but there were no any answers. May be here someone can provide a
> hint.
> 
> Thanks.
> 
> P.S I'm not on the list, so please CC me.
> 
> 
> ---------- Forwarded message ----------
> From: Hai Zaar <haizaar at gmail.com>
> Date: Feb 13, 2006 8:58 AM
> Subject: setting CONFIG_HZ=2000 makes ntpd go crazy
> To: linux-kernel at vger.kernel.org
> Cc: "Yanover, Igor" <igor.yanover at intel.com>
> 
> 
> Dear list,
> I use the patch below to speed up HZ from 1000 to 2000. I use this hack
> starting from kernel  2.6.7 and I have not experienced any particular
> problems. Recently I've started to use NTP and  have noticed that ntp
> client loose synchronization, if this patch is applied, i.e. it
> connects, synchronizes, and then after a few polls,  jitter just jumps
> to 5 digit number. I've rechecked the behavior on the kernel 2.6.11
> and results are the same - applied patch just "skews up" ntpd, while
> there are no any problems with vanilla kernels.
> 
> Is the patch incorrect in any way?
> 
This problem with Linux kernels has been discussed so frequently we know
have a Twiki entry on the subject:
https://ntp.isc.org/bin/view/Support/KnownOsIssues#Section_9.2.3.

Danny



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