Hi,
I am not sure if this is the right place to ask this question. I read this paper written by Antonios Motakis, Alexander Spyridakis, Daniel Raho about performance analysis of KVM/ARM.
I learned alot from this excellent paper. But one thing confuses me. In section 4.1, PMU cycle counter is used to measure time cost of memory allocation loop in guest's user mode. But in section 5.2, it is written that "... because the performance counters are not accessible from a guest running under KVM-on-ARM".
So, I am wondering if it is possible to use PMU cycle counter in guest, both kernel mode and user mode? I tried to use kernel module to enable user mode access to cycle counter in host and it worked. But it seems that guest kernel I am using doesn't support kernel module (I am using this one: http://www.virtualopensystems.com/media/arndale/guest-zImage). I tried to add a syscall to enable user mode access but failed either (got illegal instruction error when programming counter in user mode).
Can anyone give me any instruction or pointer on this? Thanks very much!
Btw. I am looking forward to these features because I am trying to compare kvm/x86 and kvm/arm by measuring time cost like VM_exit, VM_entry, address translation.
Best regards,
Tom Cheng
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