I''ve recently started tracking xen-unstable. One of the big changes I noticed was the split of struct domain into struct vcpu and struct domain. Could someone precisely describe how a domain is related to a VPU. By looking at the code, it seems that o each VPU is associated with a single domain o each domain can be associated with multiple VCPUs My naive understanding at this point is that a VCPU is sort of an execution container for domains (function of # of cores, # of processors, hyperthreads etc). At any single point in time, a domain must be associated with a single VPU. If and when it migrates to a different container, this association changes. But I''m not sure if thats the right way to think about it because I couldn''t see anything that points me to the "current'' VCPU of a domain. Most code that has to relate domains to VCPUs just iterates through the vpus array. TIA, Diwaker -- Web/Blog/Gallery: http://floatingsun.net _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Hi, On 7/21/05, Diwaker Gupta <diwaker.lists@gmail.com> wrote:> > I''ve recently started tracking xen-unstable. One of the big changes I > noticed was the split of struct domain into struct vcpu and struct > domain. > > Could someone precisely describe how a domain is related to a VPU. By > looking at the code, it seems that > > o each VPU is associated with a single domain > o each domain can be associated with multiple VCPUsI''m also new to Xen, but what you discribe looks like VPU = virtual processing unit. what you''ve said basically is a discription of a design to comprise that a VPU belongs to only one domain, but each domain can have several VPUs.. Why should a VPU migrate? From that description I would assume that VPUs don''t migrate from domain.. but they (possibly) can be removed from a domain has long has this stays with at least one VPU, and can be added to a domain, if such vpu isn''t assigned to a domain yet... At any single point in time, a domain> must be associated with a single VPU. If and when it migrates to a > different container, this association changes.If that''s true, there wouldn''t be SMP for domains, since they are assossiated with only one VPU. But I''m not sure if thats the right way to think about it because I> couldn''t see anything that points me to the "current'' VCPU of a > domain. Most code that has to relate domains to VCPUs just iterates > through the vpus array. > > TIA, > Diwaker > -- > Web/Blog/Gallery: http://floatingsun.net > > _______________________________________________ > Xen-users mailing list > Xen-users@lists.xensource.com > http://lists.xensource.com/xen-users >-- Miguel Sousa Filipe _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
> what you''ve said basically is a discription of a design to comprise that a > VPU belongs to only one domain, but each domain can have several VPUs.. > Why should a VPU migrate? From that description I would assume that VPUs > don''t migrate from domain.. but they (possibly) can be removed from a domain > has long has this stays with at least one VPU, and can be added to a domain, > if such vpu isn''t assigned to a domain yet...Not the VPU, I was suggesting perhaps the domain migrates from one VCPU to another.> If that''s true, there wouldn''t be SMP for domains, since they are > assossiated with only one VPU.I thought SMP support for guests was still not functional. AFAIK, domains are still pinned to a single CPU. Am I wrong? It''ll be great if someone with more authoritative knowledge can shed a light on this :) Diwaker -- Web/Blog/Gallery: http://floatingsun.net _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
> > If that''s true, there wouldn''t be SMP for domains, since they are > > assossiated with only one VPU. > > I thought SMP support for guests was still not functional. AFAIK, > domains are still pinned to a single CPU. Am I wrong?You are correct. Btw, VPU is a term you just made up, so don''t read too much into it. -- "The rules of programming are transitory; only Tao is eternal. Therefore you must contemplate Tao before you receive enlightenment." "How will I know when I have received enlightenment?" asked the novice. "Your program will then run correctly," replied the master. _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
> > > If that''s true, there wouldn''t be SMP for domains, since > they are > > > assossiated with only one VPU. > > > > I thought SMP support for guests was still not functional. AFAIK, > > domains are still pinned to a single CPU. Am I wrong? > You are correct. Btw, VPU is a term you just made up, so > don''t read too much into it.This is untrue for the unstable/3.0 tree: SMP guests are true SMP. Ian _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users