On Mon, Mar 24, 2014 at 01:20:46PM +0100, Andreas Färber wrote: > Am 21.03.2014 11:35, schrieb Igor Mammedov: > > BTW not related to hotplug but why I used link<>s: > > > > I've added link<>s as an attempt to visualize Andreas' idea to use them for > > Anthony's :) > > > hotplug and mgmt. It has it's own benefits if we try to provide more or > > less uniform QOM interface view for management. What I have in mind is that > > we could have tree like this: > > /machine/node[...]/dimm[...] > > /cpu[...]/core[...]/thread[...] > > > > where leaves are link<>s which are prebuilt at startup and set when device > > is added. It provides an easy to enumerate interface for mgmt and also > > gives us a quite informative path that encodes topology and later > > we could use it instead of custom properties. For example: > > > > device_add x86cpu,path=/machine/node[1]/cpu[0]/core[3]/thread[2] > > vs > > device_add x86cpu,apic-id=[who knows how it's calculated] > > This still collides with what Anthony and me have been saying about CPU > hot-add: It should not happen on thread level. cpu-add covers the > current approach, but device_add should add a full socket and definitely > not in that /machine/node[n]/... path. You or someone replied on Paolo's > NUMA thread that this was only as an internal convenience for lookups, > now you're pushing this as user ABI. NACK to the latter. > > I was hoping that we could let device_add auto-discover free link<> > slots like it does for buses today;
That's friendly for HMP but a huge maintainance pain. In the end hardly anyone uses HMP for hotplug so I don't think there's a lot of value in auto-discovery, make management as explicit as possible. > having two places to link the same > object would complicate that, so we need to be careful in designing our > link<>s: Having /machine/node[0]/cpu[0] be a link<> would mean no second > link<> directly on /machine/cpu[0], i.e. the NUMA node acting as a > sub-container of the board; on the other hand having a link<> to the > thread CPUState from some NUMA-specific path outside of the composition > model would still be possible due to the different link<> type but > having cpu[0] be a link to the actual socket object rules out using the > same name for a NUMA-only container object as proposed. > > > or > > device_add dimm,path=/machine/node[0]/dimm[5] > > vs > > device_add dimm,node=0,slot=5 > > > > i.e. being added device could decode all needed information from above > > provided path instead of creating a bunch of custom properties. > > Hm, the advantage of having properties there would be better error > checking in terms of restricting paths. I'd be open to having both. > > I do wonder in both cases if we should use paths relative to /machine to > avoid them cluttering the command line? > > Regards, > Andreas > > -- > SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg, Germany > GF: Jeff Hawn, Jennifer Guild, Felix Imendörffer; HRB 16746 AG Nürnberg
