Re: Screen goes blank for 1-2 seconds

From	Bijan Soleymani <bijan@psq.com>
Newsgroups	linux.debian.user
Subject	Re: Screen goes blank for 1-2 seconds
Date	2022-01-27 06:10 +0100
Message-ID	<DK5cJ-3je-3@gated-at.bofh.it> (permalink)
References	<DK4JH-2SL-1@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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On 2022-01-26 11:35 p.m., Pankaj Jangid wrote> I don’t want to file any 
bug report till I have some concrete data. So
> my question is - how do I diagnose such an issue and produce some data
> for debugging. So that I can hand it over to maintainers.

This one line script will sleep for 0.01 seconds at a time and then 
print the current time in milliseconds to a file.

while `true`; do sleep 0.01; date +"%T.%3N" ; done > time.txt

Run that and look at the output in time.txt afterwards to make sure the 
system didn't actually stop. (even if it stopped it might still be a 
graphics issue, but at least it's another data point).

Output will look like:
23:41:20.670
23:41:20.686
23:41:20.701
23:41:20.715
23:41:20.732
23:41:20.749
23:41:20.766
23:41:20.785
23:41:20.803
23:41:20.821

(due to the overhead of running sleep and date there's more than 0.01 
seconds per iteration)

This script will give you the biggest time differences:
perl -e 'while(<>){chomp; $old_time = $time; $time = $_; $old_ms = 
$cur_ms ; $_ =~ s/.*[.]//; $cur_ms = $_; $delta = $cur_ms - $old_ms; 
$delta = $delta % 1000; if (defined($old_ms)){print "$delta: $old_time 
$time\n";}}' < time.txt  | sort -n | tail

The output is:
20: 23:50:50.384 23:50:50.404
20: 23:50:51.036 23:50:51.056
20: 23:51:06.262 23:51:06.282
20: 23:51:46.577 23:51:46.597
21: 23:50:42.553 23:50:42.574
21: 23:50:43.999 23:50:44.020
24: 23:50:59.126 23:50:59.150
25: 23:50:41.680 23:50:41.705
25: 23:50:50.192 23:50:50.217
25: 23:50:53.255 23:50:53.280

So in my case the biggest delay was 25ms (at time 23:50:53). If you see 
anything longer than 100ms you'll know the system has gotten stuck 
during the blank interval.

Bijan

Thread

Screen goes blank for 1-2 seconds Pankaj Jangid <pankaj@codeisgreat.org> - 2022-01-27 05:40 +0100
  Re: Screen goes blank for 1-2 seconds David Wright <deblis@lionunicorn.co.uk> - 2022-01-27 06:00 +0100
    Re: Screen goes blank for 1-2 seconds Pankaj Jangid <pankaj@codeisgreat.org> - 2022-01-27 15:10 +0100
  Re: Screen goes blank for 1-2 seconds Bijan Soleymani <bijan@psq.com> - 2022-01-27 06:10 +0100
    Re: Screen goes blank for 1-2 seconds Pankaj Jangid <pankaj@codeisgreat.org> - 2022-01-27 15:20 +0100
  Re: Screen goes blank for 1-2 seconds "hdv@gmail" <hdv.jadev@gmail.com> - 2022-01-27 10:10 +0100
    Re: Screen goes blank for 1-2 seconds Bijan Soleymani <bijan@psq.com> - 2022-01-27 10:30 +0100
      Re: Screen goes blank for 1-2 seconds Bijan Soleymani <bijan@psq.com> - 2022-01-27 10:50 +0100
        Re: Screen goes blank for 1-2 seconds "hdv@gmail" <hdv.jadev@gmail.com> - 2022-01-27 11:10 +0100
          Re: Screen goes blank for 1-2 seconds Bijan Soleymani <bijan@psq.com> - 2022-01-27 11:20 +0100
            Re: Screen goes blank for 1-2 seconds "hdv@gmail" <hdv.jadev@gmail.com> - 2022-01-27 11:40 +0100
              Re: Screen goes blank for 1-2 seconds Bijan Soleymani <bijan@psq.com> - 2022-01-27 16:50 +0100
              Re: Screen goes blank for 1-2 seconds "hdv@gmail" <hdv.jadev@gmail.com> - 2022-02-09 21:00 +0100
    Re: Screen goes blank for 1-2 seconds Pankaj Jangid <pankaj@codeisgreat.org> - 2022-01-27 15:30 +0100
  Re: Screen goes blank for 1-2 seconds Vincent Lefevre <vincent@vinc17.net> - 2022-01-27 11:50 +0100
    Re: Screen goes blank for 1-2 seconds Vincent Lefevre <vincent@vinc17.net> - 2022-01-27 11:50 +0100
      Re: Screen goes blank for 1-2 seconds Tim Woodall <debianuser@woodall.me.uk> - 2022-01-27 12:20 +0100
        Re: Screen goes blank for 1-2 seconds Pankaj Jangid <pankaj@codeisgreat.org> - 2022-01-27 15:40 +0100
    Re: Screen goes blank for 1-2 seconds Pankaj Jangid <pankaj@codeisgreat.org> - 2022-01-27 15:40 +0100
  Re: Screen goes blank for 1-2 seconds Dan Ritter <dsr@randomstring.org> - 2022-01-27 12:40 +0100
    Re: Screen goes blank for 1-2 seconds Pankaj Jangid <pankaj@codeisgreat.org> - 2022-01-27 15:30 +0100
      Re: Screen goes blank for 1-2 seconds Pankaj Jangid <pankaj@codeisgreat.org> - 2022-01-28 08:10 +0100
        Re: Screen goes blank for 1-2 seconds Pankaj Jangid <pankaj@codeisgreat.org> - 2022-01-28 14:40 +0100
          Re: Screen goes blank for 1-2 seconds "hdv@gmail" <hdv.jadev@gmail.com> - 2022-01-28 14:50 +0100
            Re: Screen goes blank for 1-2 seconds Bijan Soleymani <bijan@psq.com> - 2022-01-28 15:40 +0100
              Re: Screen goes blank for 1-2 seconds "hdv@gmail" <hdv.jadev@gmail.com> - 2022-01-28 16:20 +0100
                Re: Screen goes blank for 1-2 seconds Bijan Soleymani <bijan@psq.com> - 2022-01-28 16:50 +0100
                Re: Screen goes blank for 1-2 seconds "hdv@gmail" <hdv.jadev@gmail.com> - 2022-01-28 17:00 +0100
                Re: Screen goes blank for 1-2 seconds "Andrew M.A. Cater" <amacater@einval.com> - 2022-01-28 17:00 +0100
                Re: Screen goes blank for 1-2 seconds "hdv@gmail" <hdv.jadev@gmail.com> - 2022-01-28 17:10 +0100
                Re: Screen goes blank for 1-2 seconds "Andrew M.A. Cater" <amacater@einval.com> - 2022-01-28 21:40 +0100
  Re: Screen goes blank for 1-2 seconds Pankaj Jangid <pankaj@codeisgreat.org> - 2022-02-06 17:10 +0100
    Re: Screen goes blank for 1-2 seconds Pankaj Jangid <pankaj@codeisgreat.org> - 2022-02-09 14:10 +0100

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