Messages in this thread | | | Date | Mon, 03 Sep 2012 14:07:30 +0300 | From | Avi Kivity <> | Subject | Re: [PATCH v7 2/3] KVM: x86: trace mmio begin and complete |
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On 08/27/2012 12:51 PM, Dong Hao wrote: > From: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com> > > 'perf kvm stat record/report' will use kvm_exit and kvm_mmio(read...) to > calculate mmio read emulated time for the old kernel, in order to trace > mmio read event more exactly, we add kvm_mmio_begin to trace the time when > mmio read begins, also, add kvm_io_done to trace the time when mmio/pio is > completed >
Why is this so critical?
If a lot of time is spent in in-kernel mmio, then 'perf top' will report it. Otherwise the time between kvm_exit and kvm_entry describes the time spent in the host. Not all of it is mmio handling, but it is quite close.
-- error compiling committee.c: too many arguments to function
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