40m QIL Cryo_Lab CTN SUS_Lab TCS_Lab OMC_Lab CRIME_Lab FEA ENG_Labs OptContFac Mariner WBEEShop
  40m Log  Not logged in ELOG logo
Entry  Thu Mar 11 14:27:56 2021, gautam, Update, CDS, timesync issue? timesync.pngc1lscMods.png
    Reply  Thu Mar 11 18:46:06 2021, gautam, Update, CDS, cds reboot CDSoverview.png
       Reply  Fri Mar 12 03:28:51 2021, Koji, Update, CDS, cds reboot 
          Reply  Fri Mar 12 11:02:38 2021, gautam, Update, CDS, cds reboot timeDrift.png
Message ID: 15904     Entry time: Thu Mar 11 14:27:56 2021     Reply to this: 15905
Author: gautam 
Type: Update 
Category: CDS 
Subject: timesync issue? 

I have recently been running into hitting the 4MB/s data rate limit on testpoints - basically, I can't run DTT TF and spectrum measurements that I was able to while locking the interferometer, which I certainly was able to this time last year. AFAIK, the major modification made was the addition of 4 DQ channels for the in-air BHD experiment - assuming the data is transmitted as double precision numbers, i estimate the additional load due to this change was ~500KB/s. Probably there is some compression so it is a bit more efficient (as this naive calc would suggest we can only record 32 channels and I counted 41 full rate channels in the model), but still, can't think of anything else that has changed. Anyway, I removed the unused parts and recompiled/re-installed the models (c1lsc and c1omc). Holding off on a restart until I decide I have the energy to recover the CDS system from the inevitable crash. For documentation I'm also attaching screenshot of the schematic of the changes made.

Anyway, the main point of this elog is that at the compilation stage, I got a warning I've never seen before:

Building front-end Linux kernel module c1lsc...
make[1]: Warning: File 'GNUmakefile' has modification time 13 s in the future
make[1]: warning:  Clock skew detected.  Your build may be incomplete.

This prompted me to check the system time on c1lsc and FB - you can see there is a 1 minute offset (it is not a delay in me issuing the command to the two machines)! I am suspecting this NTP action is the reason. So maybe a model reboot is in order. Sigh

Attachment 1: timesync.png  99 kB  | Hide | Hide all
timesync.png
Attachment 2: c1lscMods.png  405 kB  | Hide | Hide all
c1lscMods.png
ELOG V3.1.3-