Hi! I'm having some problems related to the creation of a new service offering. I need to create one using the "Custom constrained" option to limit CPUs and memory. But, when "Custom constrained" is selected "CPU (in MHz)" is required.
(1) The first problem is that "CPU (in MHz)" has nothing to do with the CPU speed, right? The value configured as "CPU (in MHz)" is mapped to "shares" element in the cputune section of libvirt configuration of domain (KVM). Apparently this mapping is done using (N. CPUs) * CPU (in MHz). So, if I have a 1000 Mhz value in service offering and try to launch a VM with 80 CPUs, I will get 80000 configured as 'shares' value. 'Shares' is a relative value that defines how much CPU time a VM will have when compared to others. This description in MHz is very confusing. Could this be changed? (2) The second problem is why is this value required? Why couldn't we just inform the number of CPUs and memory to limit the ranges that service offering permits? In UI the value is required. Looking at createServiceOffering API definition the only two required parameters are displaytext and name. But trying to create I have: create serviceoffering name="Custom VM" displaytext="Custom VM" storagetype=shared provisioningtype=fat mincpunumber=2 maxcpunumber=80 minmemory=1000 maxmemory=1000000 offerha=true dynamicscalingenabled=true Error: (HTTP 431, error code 4350) For creating a custom compute offering min/max cpu and min/max memory/cpu speed should all be null or all specified (3) The third problem is about the value of "CPU (in MHz)". According to ( libvirt.org/formatdomain.html) the value should be in range [2, 262144]. But, for operating systems using cgroup v2 the maximum value is 10000. I know that Ubuntu 22.04 I'm using here is not supported yet. But this will be an issue as other OSs adopt cgroup v2 too. So, I think this parameter deserves attention. If the value of (N. CPU) * CPU (in MHz) is greater than 10000 I get "Value specified in CPUWeight is out of range" in hypervisor. As a workaround I configured service offering with 1 Mhz. This implies that VMs with more CPUs have much more chance to get the CPU than VMs with lower number of CPUs, because besides having more CPUs, they have more chance to get the host' CPUs. VM1 10 CPU * 1 MHz -> shares = 10 VM2 80 CPU * 1 MHz -> shares = 80 If we look at 1 CPU of VM2, it will have 8 times more chance to get the host's CPU than 1 CPU of VM1, right? Thank you! :) -- Jorge Luiz Corrêa Embrapa Agricultura Digital echo "CkpvcmdlIEx1aXogQ29ycmVhCkFu YWxpc3RhIGRlIFJlZGVzIGUgU2VndXJhbm NhCkVtYnJhcGEgQWdyaWN1bHR1cmEgRGln aXRhbCAtIE5USQpBdi4gQW5kcmUgVG9zZW xsbywgMjA5IChCYXJhbyBHZXJhbGRvKQpD RVAgMTMwODMtODg2IC0gQ2FtcGluYXMsIF NQClRlbGVmb25lOiAoMTkpIDMyMTEtNTg4 Mgpqb3JnZS5sLmNvcnJlYUBlbWJyYXBhLm JyCgo="|base64 -d -- __________________________ Aviso de confidencialidade Esta mensagem da Empresa Brasileira de Pesquisa Agropecuaria (Embrapa), empresa publica federal regida pelo disposto na Lei Federal no. 5.851, de 7 de dezembro de 1972, e enviada exclusivamente a seu destinatario e pode conter informacoes confidenciais, protegidas por sigilo profissional. Sua utilizacao desautorizada e ilegal e sujeita o infrator as penas da lei. Se voce a recebeu indevidamente, queira, por gentileza, reenvia-la ao emitente, esclarecendo o equivoco. Confidentiality note This message from Empresa Brasileira de Pesquisa Agropecuaria (Embrapa), a government company established under Brazilian law (5.851/72), is directed exclusively to its addressee and may contain confidential data, protected under professional secrecy rules. Its unauthorized use is illegal and may subject the transgressor to the law's penalties. If you are not the addressee, please send it back, elucidating the failure.
