If there are two guest running one with 1 VCPU and other with 2 VCPU with equal weight and no cap on a dual core machine, how will Xen assign the physical CPUs to guests? Does Xen treats weight on domain basis? If that''s true then VCPU of domain with one VCPU will be scheduled twice as often then the VCPU of other domain. Right? _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
Hi, Agarwal It should be run as you suggested. Xen treats weight on domain basis. But this situation changes, if you pin to some vcpu to pcpu. Thanks Atsushi SAKAI "Agarwal, Lomesh" <lomesh.agarwal@intel.com> wrote:> If there are two guest running one with 1 VCPU and other with 2 VCPU > with equal weight and no cap on a dual core machine, how will Xen assign > the physical CPUs to guests? Does Xen treats weight on domain basis? If > that''s true then VCPU of domain with one VCPU will be scheduled twice as > often then the VCPU of other domain. Right? >_______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
So that means on one physical CPU domain with one VCPU will run all the time while on the other physical CPU VCPUs of other domain will alternate. Right? Can someone give me timeline of how VCPUs are scheduled on physical CPU. Domain 1 - VCPU A and B Domain 2 - VCPU C Physical CPU X and Y -----Original Message----- From: Atsushi SAKAI [mailto:sakaia@jp.fujitsu.com] Sent: Wednesday, January 31, 2007 5:09 PM To: Agarwal, Lomesh Cc: xen-devel@lists.xensource.com Subject: Re: [Xen-devel] xen scheduler question Hi, Agarwal It should be run as you suggested. Xen treats weight on domain basis. But this situation changes, if you pin to some vcpu to pcpu. Thanks Atsushi SAKAI "Agarwal, Lomesh" <lomesh.agarwal@intel.com> wrote:> If there are two guest running one with 1 VCPU and other with 2 VCPU > with equal weight and no cap on a dual core machine, how will Xenassign> the physical CPUs to guests? Does Xen treats weight on domain basis?If> that''s true then VCPU of domain with one VCPU will be scheduled twiceas> often then the VCPU of other domain. Right? >_______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
Hi, Agwal Your suggestion is right for typical cases but not guraranteed. this case should be applied for cpu-intensive jobs. Typical case is shown as follows. timeline ----> pCPUx Dom1vcpuA Dom1vcpuB pCPUY Dom2vcpuC Dom2vcpuC Typcal credit value is shown as follows For more detail see the code.(common/sched_credit.c) Every 30msec recalculate and give the credit to each vcpu. and account the credit each 10msec. Dom1vcpuA 15msec 5msec -5msec -15msec| 0msec 0msec 0msec 0msec| Dom1vcpuB 15msec 15msec 15msec 15msec|30msec 20msec 10msec 0msec| Dom2vcpuC 30msec 20msec 10msec 0msec|30msec 20msec 10msec 0msec| Thanks Atsushi SAKAI "Agarwal, Lomesh" <lomesh.agarwal@intel.com> wrote:> So that means on one physical CPU domain with one VCPU will run all the > time while on the other physical CPU VCPUs of other domain will > alternate. Right? > Can someone give me timeline of how VCPUs are scheduled on physical CPU. > Domain 1 - VCPU A and B > Domain 2 - VCPU C > Physical CPU X and Y > > -----Original Message----- > From: Atsushi SAKAI [mailto:sakaia@jp.fujitsu.com] > Sent: Wednesday, January 31, 2007 5:09 PM > To: Agarwal, Lomesh > Cc: xen-devel@lists.xensource.com > Subject: Re: [Xen-devel] xen scheduler question > > Hi, Agarwal > > It should be run as you suggested. > Xen treats weight on domain basis. > > But this situation changes, if you pin to some vcpu to pcpu. > > Thanks > Atsushi SAKAI > > > "Agarwal, Lomesh" <lomesh.agarwal@intel.com> wrote: > > > If there are two guest running one with 1 VCPU and other with 2 VCPU > > with equal weight and no cap on a dual core machine, how will Xen > assign > > the physical CPUs to guests? Does Xen treats weight on domain basis? > If > > that''s true then VCPU of domain with one VCPU will be scheduled twice > as > > often then the VCPU of other domain. Right? > > > > _______________________________________________ > Xen-devel mailing list > Xen-devel@lists.xensource.com > http://lists.xensource.com/xen-devel_______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel