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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] Offline state in scheduling
On 29/06/10 12:42, Yuyang Du wrote: Is it right to say the time HVM waits for I/O equals the offline time (given no administrator pauses)? There are some I/O events that are handled inside of Xen (such as APIC accesses); these don't cause a vcpu to be paused. I think in the normal course of operation, an HVM vcpu is only paused when doing I/O. Other reasons might be administrator pause, migration, save/restore, domain creation, memory sharing / page swapping, and so on. But if you aren't doing any of those, I think I/O done in QEMU would be the only reason. I am testing apache web server in a HVM, and I find that vcpu blocking state makes up a large portion. Since the HVM can not issue SCHED_block hypercalls, so the blocking state means the VM is not cpu intensive and often executes HLT to halt itself? Yes. If you take a trace to include VMX / SVM events, and use xenalyze, you should be able to see the HLT vmexit before blocking. -George _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel
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