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<== Date ==> <== Thread ==>

Subject: Re: drvTS/NTP issues?
From: "Brian McAllister" <[email protected]>
To: Peregrine McGehee <[email protected]>
Cc: [email protected]
Date: Thu, 01 Nov 2001 10:34:44 -0500
>>> On 10/31/2001 at 20:44:27 MST, Peregrine McGehee wrote:

  > we find that the IOC will sometimes and suddenly fall behind in
  > chunks of about 10 seconds - and never recover. The IOC has been as
  > much as 40 seconds behind the NTP clock.

  > We are running EPICS R3.13.1 on MVME-162s (old style and Petra) and
  > vxWorks 5.1.1.

This is a bug in EPICS NTP support which was fixed in R3.13.2.

>From the release notes:

>>> Changes since 3.13.1
>>> 
>>> drvTS.c 
>>> 
>>>     Fixed bug where time sync UDP client was getting in a state where
>>>     it was using the response from the previous request, and ending up
>>>     setting the time 10 seconds back.

The fix was essentially to always read all responses from the receive queue
(not just the first one) and use the latest one.

The only solution for R3.13.1 and earlier is to reboot the IOC.

----
Brian McAllister                    Controls Programmer/Beam Physicist
[email protected]                        MIT-Bates Linear Accelerator
(617) 253-9537                                           Middleton, MA


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