[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-users] Setting CPU (core) frequency from dom0
Hi Kevin, Thank you very much for the reply. PLease see comments below. Alberto On Wed, Nov 19, 2008 at 7:05 PM, Tian, Kevin <kevin.tian@xxxxxxxxx> wrote:
I would like to control frequency from dom0. I want to arbitrarily set the CPU frequency to a value and have it stay there (regardless of the load on that CPU) until I change it.
Yes, I thik this is what I need (ability to manually change frequency). Do you have an ETA (estimated time of arrival) for that functionality?
OK. I will do that. By the way, I have been running onto an error when booting (in mode A). The function cpufreq_time_setup() in linux-2.6.18-xen.hg/arch/i386/kernel/time-xen.c is printing the following message during boot (and returning -ENODEV to its caller): failed to set up cpufreq notifier Further examination of the code shows that this happens when notifier_chain_register() in linux-2.6.18-xen.hg/kernel/sys.c returns 0. The problem is that in the code I have, that function ALWAYS returns 0. The code for that function is as follows: static int notifier_chain_register(struct notifier_block **nl, struct notifier_block *n) { while ((*nl) != NULL) { if (n->priority > (*nl)->priority) break; nl = &((*nl)->next); } n->next = *nl; rcu_assign_pointer(*nl, n); return 0; } think (but are not 100% sure yet) that as a result of this error, dom0 is not creating a cpufreq /sys interface (i.e Do you happen to know what may be going on? perhaps I am just misreading the code? or perhaps not disabling PROCESSOR_EXTERNAL_CONTROL is what is causing this behavior? I will run some experiments on this last thing today. Thanks again, Alberto
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