On Fri, 2014-02-21 at 15:28 +0800, Lei Wen wrote:
> Actually, what I have experiment is as:
> 1. set top cpuset as disable load balance
> 2. set 0-2 cpus to "system", and enable its load balance
> 3. set 3 cpu to "rt" and disable load balance.
Exactly as I do, pertinent part of my cheezy script being...
# ...and fire up the shield
cset shield --userset=rtcpus --cpu=${START_CPU}-${END_CPU} --kthread=on
# If cpuset wasn't previously mounted (no obnoxious systemd),
# we just mounted it. Find the mount point.
if [ -z $CPUSET_ROOT ]; then
CPUSET_ROOT=$(grep cpuset /proc/mounts|cut -d ' ' -f2)
if [ -z $CPUSET_ROOT ]; then
# If it's not mounted now, bail.
echo EEK, cupset is not mounted!
exit
else
# ok, check for cgroup mount
if [ -f ${CPUSET_ROOT}/cpuset.cpus ]; then
CPUSET_PREFIX=cpuset.
fi
fi
fi
echo 0 > ${CPUSET_ROOT}/${CPUSET_PREFIX}sched_load_balance
echo 1 > ${CPUSET_ROOT}/system/${CPUSET_PREFIX}sched_load_balance
echo 0 > ${CPUSET_ROOT}/rtcpus/${CPUSET_PREFIX}sched_load_balance
echo 0 > ${CPUSET_ROOT}/rtcpus/${CPUSET_PREFIX}sched_relax_domain_level
> While by this way, root span always covering [0-2] which is seen
> by cpu 0-2, as you also mentioned.
> And it is true that if I disable load balance, I would see span mask
> get them merged.
>
> So how about below change?
> + if (!this_rq()->sd)
> + return;
> Suppose isolated cpu would lose its sd, could you help
> confirm it from crash too?
Yeah, isolated CPUs have no sd connectivity. I sent Peter a patchlet
offline showing what I do to keep nohz at bay.
> Or, you think it is wrong to do merge job when system group disable
> the load balance?
I think the construction stuff works fine, and !->sd is the perfect cue
to tell various things to keep their grubby mitts off of a CPU.
-Mike
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