On 07/06/16 09:39, Daniel Bristot de Oliveira wrote:

Ciao Juri,

Ciao, :-)

On 06/07/2016 07:14 AM, Juri Lelli wrote:

quoted

Interesting. And your test is using cpuset controller to partion
DEADLINE tasks and then modify groups concurrently?

Yes. I was studying the partitioning/admission control of the
deadline scheduler, to document it.

I was using the minimal task from sched deadline's documentation
as the load (the ./m in the bellow script). 

Here is the script I was using in the test:

Thanks for sharing it. It is somewhat similar to some of my test
scripts, but I've got a question below.

-----------%<------------------------------------------------------------
#!/bin/sh

# I am running on a 8 cpus box, you need to adjust the
# cpu mask to match to your cpu topology.

cd /sys/fs/cgroup/cpuset

# global settings
# echo 1 > cpuset.cpu_exclusive
echo 0 > cpuset.sched_load_balance

# a cpuset to run ordinary load:

if [ ! -d ordinary ]; then
	mkdir ordinary
	echo 0-3 > ordinary/cpuset.cpus
	echo 0 > ordinary/cpuset.mems
	echo 0 > ordinary/cpuset.cpu_exclusive
	# the load balance can be enabled on this cpuset.
	echo 1 > ordinary/cpuset.sched_load_balance
fi

# move all threads to ordinary cpuset 
ps -eL -o lwp | while read tid; do
	echo $tid >> ordinary/tasks 2> /dev/null || echo "thread $tid is pinned or died"
done

echo $$ > ordinary/tasks
cat /proc/self/cpuset
~/m &

# a single cpu cpuset (partitioned)
if [ ! -d partitioned ]; then
	mkdir partitioned
	echo 4 > partitioned/cpuset.cpus
	echo 0 > partitioned/cpuset.mems
	echo 0 > partitioned/cpuset.cpu_exclusive
fi

echo $$ > partitioned/tasks
cat /proc/self/cpuset
~/m &

# a set of cpus (clustered)
if [ ! -d clustered ]; then
	mkdir clustered
	echo 5-7 > clustered/cpuset.cpus
	echo 0 > clustered/cpuset.mems
	echo 0 > clustered/cpuset.cpu_exclusive

So, this and the partitioned one could actually overlap, since we don't
set cpu_exclusive. Is that right?

I guess affinity mask of both m processes gets set correclty, but I'm
not sure if we are missing one check in the admission control. Can you
actually create two overlapping sets and get DEADLINE tasks running in
them? For example, what happens if partitioned is [4] and clustered is
[4-7]? Does setattr() fail?

It is not really related to this patch, I'm just wondering if there is
another problem lying around.

Thanks,

- Juri

	# the load balance can be enabled on this cpuset.
	echo 1 > clustered/cpuset.sched_load_balance
fi

echo $$ > clustered/tasks
cat /proc/self/cpuset
~/m
----------->%------------------------------------------------------------

The problem rarely reproduces.

-- Daniel