Re: [libvirt] [PATCH 0/3] RFC: qemu: drop vioserialaddr cache

On 05/14/2016 02:25 PM, Cole Robinson wrote: > qemuDomainObjPrivate caches three lists of device addresses: > > virDomainPCIAddressSetPtr pciaddrs; > virDomainCCWAddressSetPtr ccwaddrs; > virDomainVirtioSerialAddrSetPtr vioserialaddrs; > > Yet I can't quite tell what issue they fix... they are only used > at hotplug time for checking for address collisions, however it > appears that we can generate those lists on demand from the runtime > XML, which contains all the info we need. > > In truth I only looked deeply at the vioserialaddrs list... perhaps > PCI has more to it. But at least for virtio serial it looks like > this caching can be dropped. CCing jtomko who originally added it > > If this is acceptable, dropping all the caching will be a step > towards unifying all uses of qemuDomainAssignAddresses, rather > than sprinkling around a dozen call sites throughout the code. FWIW, when I was doing stuff that touched address assignment, I noticed that priv->persistentAddrs was set to 1/0 by each of the qemuDomainAssign*Addresses() functions without regard to whether or not it had already been set by one of the other qemuDomainAssign*Addresses() functions. This meant that, for example, the VirtioSerial version could set persistentAddrs = 1, and then the PCI version could reset it back to 0. Since nobody had complained and I truthfully don't know what the usefulness of the cache is, I didn't touch it. It does look like any domain that has no PCI addresses ends up with persistentAddrs == 0, so probably the cache is empty anyway (? I guess. I didn't actually look at what's behind that faux-boolean).