Linux compatibility layer - ulimit - pthread_setschedparam failed: Operation not permitted

[Petr Fischer]

Hello,

I need to run some smalltalk VM (linux binary), that uses thread with higher priority for something like "heartbeat", and when I run this binary (VM) as regular user, this error occurs:

pthread_setschedparam failed: Operation not permitted

When I run it with "sudo" (as root user), everything is OK.

So I thought, OK, if it needs root access, it's a security risk and I will run it in isolated jail (created by ezjail)! But, there is another problem - in a jail, it does not work even with root permissions (sudo, root user inside jail), this error again:

pthread_setschedparam failed: Operation not permitted

Can I do something with this situation, I listed all sysctl vars, but nothing interesting, there is for example "security.bsd.unprivileged_idprio", but that is for idle priority, not realtime priority (not found something like *.rtprio).

Any ideas please? Thanks! pf