[Fuego] [PATCH v2] Benchmark.cyclictest: add a warning for rt

Daniel Sangorrin daniel.sangorrin at toshiba.co.jp
Mon Nov 5 05:26:20 UTC 2018


Hi Tim,

> -----Original Message-----
> From: fuego-bounces at lists.linuxfoundation.org
> <fuego-bounces at lists.linuxfoundation.org> On Behalf Of Tim.Bird at sony.com
> Sent: Saturday, November 3, 2018 9:15 AM
> To: lixm.fnst at cn.fujitsu.com; fuego at lists.linuxfoundation.org
> Subject: Re: [Fuego] [PATCH v2] Benchmark.cyclictest: add a warning for rt
> 
> 
> 
> > -----Original Message-----
> > From: Li Xiaoming on  Thursday, November 01, 2018 8:35 PM
> >
> > details: add a warning if CONFIG_RT_GROUP_SCHED enabled in kernel.
> >
> > Signed-off-by: Li Xiaoming <lixm.fnst at cn.fujitsu.com>
> > ---
> >  engine/tests/Benchmark.cyclictest/fuego_test.sh | 8 ++++++++
> >  1 file changed, 8 insertions(+)
> >
> > diff --git a/engine/tests/Benchmark.cyclictest/fuego_test.sh
> > b/engine/tests/Benchmark.cyclictest/fuego_test.sh
> > index 319f361..d233b87 100755
> > --- a/engine/tests/Benchmark.cyclictest/fuego_test.sh
> > +++ b/engine/tests/Benchmark.cyclictest/fuego_test.sh
> > @@ -4,6 +4,14 @@ NEED_ROOT=1
> >
> >  function test_pre_check {
> >      assert_define BENCHMARK_CYCLICTEST_PARAMS
> > +
> > +    if check_kconfig "CONFIG_RT_GROUP_SCHED=y"; then
> > +        echo "WARNING: CONFIG_RT_GROUP_SCHED enabled in your kernel.
> > Please check the RT"
> > +        echo "settings as following if this test failed with 'Unable to change
> > scheduling policy'."
> > +        echo "- If the user does not need the RT groups functionality, disable
> > CONFIG_RT_GROUP_SCHED and compile the kernel again, or 'sysctl -w
> > kernel.sched_rt_runtime_us=-1'"
> > +        echo "- If the user does want to use RT groups functionality, put the
> > sshd daemon into a cgroup with assigned runtime"
> 
> This last bullet point seems to be missing a word.  I don't understand it.
> 
> Can you please describe more what it means to "put the ssh daemon into a cgroup
> with
> assigned runtime"?

Sorry about that. How about using this wording?

"Assign the ssh daemon service a realtime budget by specifying the cpu.rt_runtime_us attribute."

For a longer desciption check here:
https://www.freedesktop.org/wiki/Software/systemd/MyServiceCantGetRealtime/
A third option is to simply assign your service a realtime budget. For that use ControlGroupAttribute=cpu.rt_runtime_us 500000 in its [Service] or suchlike. See the kernel documentation for details. The latter two options are not available for System V services. A possible solution is to write a small wrapper service file that simply calls the SysV script's start verb in ExecStart= and the stop verb in ExecStop=. (It also needs to set RemainAfterExit=1 and Type=forking!)

Thanks,
Daniel





> 
> > +    fi
> > +
> >  }
> >
> >  function test_build {
> > --
> > 2.7.4
> 
> 
> I applied this patch, but some more clarity in the wording might be nice.
>  -- Tim
> 
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