Hi, With my college, I was wondering what is the best optimization for our setup. I''ve got 2 VM with 16GB of RAM and 4 vCPU to each one. My server got 2 CPU with 4 cores inside (makes 8 CPU). What produce the best performance : 1) Give ALL cpu to my 2 VM and each ones will take its 4 vCPU where it can 2) Give CPU 0-3 to VM1 and CPU 4-7 to VM2 : each vm own the 4 cores from 1 CPU 3) Give CPU 0,1,4,5 to VM1 and 2,3,6,7 to VM2 : mix cores between the both CPU Thanks by advance for any information or point me to any docs talking about this ! _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Hi, you can asign all DomUs all cores. In the case of 100% utilisation of both DomUs, the xen-scheduler provides 50% CPU time from all the CPUs for each DomU. If one DomU idles and the other one, need 100% CPU, it will get the power of all the 8 Cores. Regards - Michael Schmidt L.M.J schrieb:> Hi, > > With my college, I was wondering what is the best optimization for our > setup. I''ve got 2 VM with 16GB of RAM and 4 vCPU to each one. My server got > 2 CPU with 4 cores inside (makes 8 CPU). What produce the best performance > : > 1) Give ALL cpu to my 2 VM and each ones will take its 4 vCPU where it > can > 2) Give CPU 0-3 to VM1 and CPU 4-7 to VM2 : each vm own the 4 cores from > 1 CPU > 3) Give CPU 0,1,4,5 to VM1 and 2,3,6,7 to VM2 : mix cores between the > both CPU > > Thanks by advance for any information or point me to any docs talking > about this ! > > _______________________________________________ > Xen-users mailing list > Xen-users@lists.xensource.com > http://lists.xensource.com/xen-users >_______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Hi, Xen has different CPU schedulers. The default is the credit scheduler - this is a "fair" scheduler. Here cou can read more about it: http://wiki.xensource.com/xenwiki/CreditScheduler Mit freundlichen Gruessen / Best Regards Michael SchmidtAm 09.04.10 09:09, schrieb L.M.J:> On Fri, 02 Apr 2010 10:29:53 +0200, Michael Schmidt > <michael.schmidt@xncore.com> wrote: > >> Hi, >> >> you can assign all DomUs all cores. >> In the case of 100% utilization of both DomUs, the xen-scheduler >> provides 50% CPU time from all the CPUs for each DomU. >> If one DomU idles and the other one, need 100% CPU, it will get the >> power of all the 8 Cores. >> > Thanks Michael for your fast reply. I would like to share what I''ve heard > from Vmware : when you assigned 4 CPU to a VM, Vmware wait to have 4 cores > free at the same time before give them to the VM which could slow down your > VM instead of speed up. > Is there the same issue with Xen ? > > > >> L.M.J schrieb: >> >>> Hi, >>> >>> With my college, I was wondering what is the best optimization for our >>> setup. I''ve got 2 VM with 16GB of RAM and 4 vCPU to each one. My server >>> got 2 CPU with 4 cores inside (makes 8 CPU). What produce the best >>> performance : >>> 1) Give ALL cpu to my 2 VM and each ones will take its 4 vCPU where it >>> > can > >>> 2) Give CPU 0-3 to VM1 and CPU 4-7 to VM2 : each vm own the 4 cores >>> > from 1 CPU > >>> 3) Give CPU 0,1,4,5 to VM1 and 2,3,6,7 to VM2 : mix cores between the >>> > both CPU > >>> Thanks by advance for any information or point me to any docs talking >>> > about this ! > >_______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
The question you ask is a multidimensional optimization of a function that has discontinuities and depends on both the nature of workloads and the specifics of the CPUs. What specific CPUs are you referring to? Basic rule: 1. Dedicate a single core to dom0 (a core meaning real core not a hyperthread path that looks like a core to an OS). 2. Limit dom0 to 512mb or less memory That''s it. Anything else is likely talk and theorizing that is simply wasting air. Far better to deploy your rotliafs and start testing. I''ll be amazed if configuration of the credit scheduler has a substantive impact at this point. Peter Sent from my iPhone On Apr 9, 2010, at 3:27 AM, Michael Schmidt <michael.schmidt@xncore.com> wrote:> Hi, > > Xen has different CPU schedulers. The default is the credit > scheduler - this is a "fair" scheduler. > Here cou can read more about it: > > http://wiki.xensource.com/xenwiki/CreditScheduler > > Mit freundlichen Gruessen / Best Regards > > Michael SchmidtAm 09.04.10 09:09, schrieb L.M.J: > >> On Fri, 02 Apr 2010 10:29:53 +0200, Michael Schmidt >> <michael.schmidt@xncore.com> wrote: >> >>> Hi, >>> >>> you can assign all DomUs all cores. >>> In the case of 100% utilization of both DomUs, the xen-scheduler >>> provides 50% CPU time from all the CPUs for each DomU. >>> If one DomU idles and the other one, need 100% CPU, it will get the >>> power of all the 8 Cores. >>> >> Thanks Michael for your fast reply. I would like to share what I''ve >> heard >> from Vmware : when you assigned 4 CPU to a VM, Vmware wait to have >> 4 cores >> free at the same time before give them to the VM which could slow >> down your >> VM instead of speed up. >> Is there the same issue with Xen ? >> >> >> >>> L.M.J schrieb: >>> >>>> Hi, >>>> >>>> With my college, I was wondering what is the best optimization >>>> for our >>>> setup. I''ve got 2 VM with 16GB of RAM and 4 vCPU to each one. My >>>> server >>>> got 2 CPU with 4 cores inside (makes 8 CPU). What produce the best >>>> performance : >>>> 1) Give ALL cpu to my 2 VM and each ones will take its 4 vCPU >>>> where it >>>> >> can >> >>>> 2) Give CPU 0-3 to VM1 and CPU 4-7 to VM2 : each vm own the 4 >>>> cores >>>> >> from 1 CPU >> >>>> 3) Give CPU 0,1,4,5 to VM1 and 2,3,6,7 to VM2 : mix cores >>>> between the >>>> >> both CPU >> >>>> Thanks by advance for any information or point me to any docs >>>> talking >>>> >> about this ! >> >> > > _______________________________________________ > Xen-users mailing list > Xen-users@lists.xensource.com > http://lists.xensource.com/xen-users_______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users