Re: [LAD] Realtime threads and security

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From: Fons Adriaensen <fons@...>

To: <linux-audio-dev@...>

Subject: Re: [LAD] Realtime threads and security

Date: Thursday, February 17, 2011 - 10:04 pm

On Thu, Feb 17, 2011 at 10:53:54PM +0100, Robin Gareus wrote:

> /proc/sys/kernel/sched_rt_runtime_us

quoted text

> /proc/sys/kernel/sched_rt_period_us
>
> > I've been told than on OSX, when a process runs in realtime, it is only allowed
> > to use a certain ratio of CPU time. And if it goes over this limit, it loses its
> > priority. Is there something comparable on Linux? Maybe with the files in
> > /proc/sys that you mention?
>
> not exactly. /proc kernel.sched_rt_runtime_us globally limits realtime
> scheduling time. To limit it per process you'll need cgroups.

Still this provides protection against any RT-process that goes
out of control. If the limit is exceeded, all RT procs will be
blocked for the next sched_rt_period_us (default seems to be 1s),
which should give you the opportunity to kill the offending process.

There seem to be some restrictions on runtime / period, this must
be between 0.95 and 1.00 or zero. Which means that in order to adjust
period you first need to set runtime to zero, then adjust period, then
reset runtime to a value within the accepted range.

--
FA

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Messages in current thread:

[LAD] Realtime threads and security, Olivier Guilyardi, (Thu Feb 17, 8:40 pm)

Re: [LAD] Realtime threads and security, Daniel Poelzleithner, (Fri Feb 18, 1:43 pm)

Re: [LAD] Realtime threads and security, Olivier Guilyardi, (Wed Feb 23, 10:10 am)

Re: [LAD] Realtime threads and security, Daniel Poelzleithner, (Wed Feb 23, 5:24 pm)

Re: [LAD] Realtime threads and security, Olivier Guilyardi, (Fri Feb 25, 3:23 pm)

Re: [LAD] Realtime threads and security, Paul Davis, (Fri Feb 25, 3:29 pm)

Re: [LAD] Realtime threads and security, torbenh, (Fri Feb 25, 3:56 pm)

Re: [LAD] Realtime threads and security, Olivier Guilyardi, (Fri Feb 25, 3:54 pm)

Re: [LAD] Realtime threads and security, Paul Davis, (Fri Feb 25, 4:32 pm)

Re: [LAD] Realtime threads and security, Olivier Guilyardi, (Fri Feb 25, 4:40 pm)

Re: [LAD] Realtime threads and security, Olivier Guilyardi, (Fri Feb 25, 4:31 pm)

Re: [LAD] Realtime threads and security, Paul Davis, (Fri Feb 25, 4:33 pm)

Re: [LAD] Realtime threads and security, Olivier Guilyardi, (Fri Feb 25, 4:49 pm)

Re: [LAD] Realtime threads and security, Paul Davis, (Fri Feb 25, 4:54 pm)

Re: [LAD] Realtime threads and security, Paul Davis, (Thu Feb 17, 8:48 pm)

Re: [LAD] Realtime threads and security, Olivier Guilyardi, (Thu Feb 17, 9:27 pm)

Re: [LAD] Realtime threads and security, Robin Gareus, (Thu Feb 17, 9:54 pm)

Re: [LAD] Realtime threads and security, Olivier Guilyardi, (Wed Feb 23, 10:22 am)

Re: [LAD] Realtime threads and security, Robin Gareus, (Wed Feb 23, 7:28 pm)

Re: [LAD] Realtime threads and security, Olivier Guilyardi, (Thu Feb 24, 2:59 pm)

Re: [LAD] Realtime threads and security, Robin Gareus, (Thu Feb 24, 6:01 pm)

Re: [LAD] Realtime threads and security, Olivier Guilyardi, (Thu Feb 24, 7:09 pm)

Re: [LAD] Realtime threads and security, Fons Adriaensen, (Thu Feb 17, 10:04 pm)

Re: [LAD] Realtime threads and security, Olivier Guilyardi, (Fri Feb 18, 12:17 pm)

Re: [LAD] Realtime threads and security, torbenh, (Fri Feb 18, 11:19 am)

Re: [LAD] Realtime threads and security, Paul Davis, (Thu Feb 17, 9:55 pm)