[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] Granularity of Credit and RTDS Scheduler
Dear Xen developers,Recently I read a paper about possible theft of service attacks in Xen hypervisor. https://arxiv.org/pdf/1103.0759.pdfDue to the 10 ms intervals between sampling points, a malicious VM is able to run less than a interval and sleep to avoid being accounted. According to the info page of RTDS, it seems that after V4.7, a RTDS based scheduler achieves a granularity of microsecond. However, is it able that a VM runs for less than a microsecond and relinquish the host actively so as to keep its budget? A similar problem occurs in earlier Linux kernel, and it is fixed in today's Linux on x86 machines by utilizing a clock source TSC with a granularity of nanoseconds. I'd like to know if there is any reason that the Xen hypervisor does not choose a nanosecond scheduler? Thanks a lot. Best, Wenqiu _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx https://lists.xen.org/xen-devel
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