Re: [libvirt] [PATCH V3 1/2] Intorduce file descriptor set for QEMU domains

On Thu, Feb 07, 2013 at 12:56:45PM -0500, Stefan Berger wrote: > On 02/07/2013 10:12 AM, Daniel P. Berrange wrote: >> On Mon, Feb 04, 2013 at 07:12:37PM -0500, Stefan Berger wrote: >>> Create field in virDomainDeviceInfo structure to hold >>> file descriptor set the device is associated with. Have >>> the number written into the Device Info XML and parsed >> >from the XML. >>> Remember the next-toy use file descriptor set in the QEMU >>> private domain structure. >>> Upon libvirt restart determine the maximum file descriptor >>> set used in the Device Info XML and remember the >>> next-to-use file descriptor set in the QEMU private domain >>> structure. >>> >>> Upon termination of a domain, reset the next-to-use file >>> descriptor set to its initial value '1'. >>> >>> Stefan Berger <stefanb(a)linux.vnet.ibm.com&gt; >>> >>> --- >>> src/conf/capabilities.h | 5 ++++- >>> src/conf/domain_conf.c | 20 +++++++++++++++++--- >>> src/conf/domain_conf.h | 1 + >>> src/lxc/lxc_domain.c | 3 ++- >>> src/qemu/qemu_domain.c | 23 ++++++++++++++++++++++- >>> src/qemu/qemu_domain.h | 2 ++ >>> src/qemu/qemu_process.c | 2 ++ >>> 7 files changed, 50 insertions(+), 6 deletions(-) >> I really don't like the fact that we're modifying the virDomainDef >> structs, which are intended to hold static config description, to >> also hold QEMU specific dynamic state. We did this in the past >> before we had the per-driver 'privateData' associated with >> virDomainObjPtr instances. > In these patches we are storing the fdset that's in use by a > particular device in the virDomainDeviceInfo structure and are > persisting that fdset number next to the device's alias into XML > written into /var/run/libvirt/qemu to be able to restore it upon > libvirt restart. Now we would either need a similar per-device > structure in parallel to those virDomainDeviceInfo structures or > connect a QEMU private data structure to that virDomainDeviceInfo > structure for storing the dynamic data and to keep reference back to > the device. Not sure what's the best path ... Just have a hashtable mapping device alias names -> fd set numbers in the qemuDomainObjPrivatePtr, and write that out in the QEMU private XML. There's no need to directly mirror the structs.