Re: changing ulimit from rc.local in order to start audio scripts from there

Paul Davis <paul@xxxxxxxxxxxxxxxxxxxxx> · Mon, 9 Oct 2017 18:00:07 -0400

renice has nothing to do with realtime scheduling and is of no use or importance in tuning scheduling of realtime applications.

On Mon, Oct 9, 2017 at 4:09 PM, Bill Purvis <bill@xxxxxxxxx> wrote:

    On 09/10/17 19:15, Athanasios Silis
      wrote:

                Hi there,

                I have setup an audio system around jackd based on
                ubuntu studio (14.04 LTS). I have written various
                scripts to setup jackd and clients. It is tested and up
                running. Now I would like to add a cmd in rc.local in
                order for the whole system to be brought up at boot.

              I tried

            #set limits

            su - nass -c "ulimit -r 95 -l unlimited" 2>&1 |
              tee -a  /tmp/audio.log

            #verify limits

            su - nass -c "ulimit -r -l" 2>&1 | tee -a 
              /tmp/audio.log

            #boot audio stuff

            su - nass -c "cd /home/nass/audio_setup/scripts ; bash
              ./cmdaudio start" 2>&1 | tee -a  /tmp/audio.log

            However the ulimit "set" command fails with message

            ulimit: real-time priority: cannot modify limit: Operation
            not permitted

          I read that ulimits are not ready yet at this time. Is there a
          way to forcefully "bring them up" in order to have them set
          for the user "nass" before starting the audio scripts ??

        Thank you

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    ulimit is built-in to the command shell program. I'd suggest you
      encase your commands in a shell script

      with the ulimit at the start, and invoke that, via su, from
      rc.local.

      However, I suspect that will still reject the request. I'd suggest
      you look at starting the programs,

      then use the renice command (see man renice) to alter the priority
      once they are running.

      You need to be root to raise the priority of a process above
      normal.

      Bill

    -- 
+----------------------------------------+
| Bill Purvis                            |
| email: bill@xxxxxxxxx                  |
+----------------------------------------+

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