Cc: Paul Jackson <pj@...>, <linux-kernel@...>, Con Kolivas <kernel@...>, Derek L. Fults <dfults@...>, devik <devik@...>, Dinakar Guniguntala <dino@...>, Emmanuel Pacaud <emmanuel.pacaud@...>, Frederik Deweerdt <deweerdt@...>, Ingo Molnar <mingo@...>, Matthew Dobson <colpatch@...>, Nick Piggin <nickpiggin@...>, <rostedt@...>, Oleg Nesterov <oleg@...>, Paul E. McKenney <paulmck@...>, Paul Menage <menage@...>, Peter Zijlstra <a.p.zijlstra@...>, Randy.Dunlap <rddunlap@...>, <suresh.b.siddha@...>, Thomas Gleixner <tglx@...>
Ah, I know exactly what you're talking about. However this is non-issue these
days. In order to clear cpuN from all the timers and other things all you need
to do is to bring that cpu off-line
echo 0 > /sys/devices/cpu/cpuN/online
and then bring it back online
echo 1 > /sys/devices/cpu/cpuN/online
There are currently a couple of issues with scheduler domains and hotplug
event handling. I do have the fix for them, and Paul had already acked it.
btw Disabling scheduler load balancer is not enough. Some timers are started
from the hard- and soft- irq handlers. Which means that you have to also
ensure that those CPUs do not handle any irqs (at least during
initialization). See my latest "default IRQ affinity" patch.
Because the same functionality is available via more flexible mechanism that
is actively supported. isolcpus= is a static mechanism that requires reboots.
cpusets and cpu hotplug let you dynamically repartition the system at any time.
Also isolcpus= conflicts with the scheduler domains created by the cpusets.
I'd either nuke it or expose it when cpusets are disabled.
In other words
- if cpusets are enabled people should use cpusets to configure cpu resources.
- if cpusets are disabled then we could provide a sysctl (sched_balancer_mask
for example) that lets us control which cpus are balanced and which aren't.
Max
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