Messages in this thread | | | From | Jeff Moyer <> | Subject | Re: the maxcpus= boot parameter broke somewhere along the line | Date | Mon, 02 Apr 2012 10:38:27 -0400 |
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"Srivatsa S. Bhat" <srivatsa.bhat@linux.vnet.ibm.com> writes:
> On 04/02/2012 07:35 PM, Jeff Moyer wrote: > >> "Srivatsa S. Bhat" <srivatsa.bhat@linux.vnet.ibm.com> writes: >> >>> Looking at the mention of udev above, and considering the commit you bisected >>> to, I think it would be good to see whether someone is writing 1 to >>> /sys/device/system/cpu/cpu*/online and hence the cpus are getting hot-added >>> towards the end of boot. Maybe that sounds stupid, but worth a try :) >>> >>> So can you try the debug patch below? It applies on latest linux-3.3-rc6+ >> >> Sorry it took me so long to get back to you. You're patch did, in fact, >> trigger: >> >> udev: starting version 147 >> CPU 3 online initated from userspace >> SMP alternatives: switching to SMP code >> WARNING! power/level is deprecated; use power/control instead >> Booting Node 0 Processor 3 APIC 0x3 >> NMI watchdog: enabled, takes one hw-pmu counter. >> CPU 1 online initated from userspace >> Booting Node 0 Processor 1 APIC 0x2 >> NMI watchdog: enabled, takes one hw-pmu counter. >> CPU 2 online initated from userspace >> Booting Node 0 Processor 2 APIC 0x1 >> NMI watchdog: enabled, takes one hw-pmu counter. >> CPU 1 online initated from userspace >> CPU 3 online initated from userspace >> CPU 2 online initated from userspace >> > > > Aha! Just like I thought! > So there is no kernel bug with respect to the maxcpus= boot parameter :-)
But this IS a change in behaviour (using older kernels, the maxcpus= boot parameter works just fine). So, what exactly has changed is my question, and what is the right way to fix it?
Cheers, Jeff
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