To: Ingo Oeser <ioe-lkml@...>, Dimitri Sivanich <sivanich@...>
Cc: Peter Zijlstra <a.p.zijlstra@...>, 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@...>, Randy.Dunlap <rddunlap@...>, <suresh.b.siddha@...>, Thomas Gleixner <tglx@...>
>> I would really appreciate some way to keep the kernel from using
btw Ingo, I just realized that maxcpu= option is exactly what you need.
Here is how you can use it.
Boot your system with maxcpus=1. That way the kernel will only bring up
processor 0. I'm assuming cpu0 is "good" otherwise your system is totally
busted :). Other cpus will stay off-line and will not be initialized.
Then once the system boots you can selectively bring "good" processors online
by doing
echo 1 > /sys/devices/system/cpu/cpuN/online
This actually solves the case you're talking about (ie ignoring bad
processors) instead of partially covering it with isolcpus=.
Dimitri, you can probably use that too. ie Boot the thing with most CPUs
offline and then bring them online. That way you'll know for sure that no
timers, works, hard-/soft-irqs, etc are running on them.
So I expect two ACKs for isolcpu= removal from both of you, in bold please :)
Max
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