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[Xen-devel] Re: Xen scheduler
On 21/04/07 06:03 +0000, pak333@xxxxxxxxxxx wrote:
Hi, On running on a dual/quad core does the Xen scheduler take into account the physical layout of the cores. For example if a VM has two vcpus, and there are 4 physical cpus free, will it take care to assign the 2vcpus (from a VM) to 2 pcpus on the same socket.
The scheduler only knows the affinity of vcpus for physical cpus. The affinity is determined by a userspace application and can be modified using a domain control hypercall. Look inxen/common/domctl.c around line 568 for the following:
case XEN_DOMCTL_setvcpuaffinity: case XEN_DOMCTL_getvcpuaffinity: When the credit scheduler migrates a vcpu to a pcpu, it only considers pcpus for which the affinity bit is set. If the userspace application sets affinity such that only the bits set for pcpus on the same socket, then the vcpu will only run on pcpu's sharing the samesocket.
Mike -- Mike D. Day IBM LTC Cell: 919 412-3900 Sametime: ncmike@xxxxxxxxxx AIM: ncmikeday Yahoo: ultra.runner PGP key: http://www.ncultra.org/ncmike/pubkey.asc _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel
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