Re: [libvirt] [PATCH 00/11] Avoid numerous calls of virQEMUCapsCacheLookup

For a domain definition there are numerous calls of virQEMUCapsCacheLookup (the same applies to the domain start). This slows down the process since virQEMUCapsCacheLookup validates that the QEMU capabilitites are still valid (among other things, a fork is done for this if the user for the QEMU processes is 'qemu'). Therefore let's reduce the number of virQEMUCapsCacheLookup calls whenever possible and reasonable. In addition to the speed up, there is the risk that virQEMUCapsCacheLookup returns different QEMU capabilities during a task if, for example, the QEMU binary has changed during the task. The correct way would be: - get the QEMU capabilities only once per task via virQEMUCapsCacheLookup - do the task with these QEMU capabilities or - abort the task after a cache invalidation Note: With this patch series the behavior is still not (completely) fixed, but the performance has been significantly improved. In a quick test this gave a speed up of factor 4 for a simple define/undefine loop. In general, the more devices a domain has, the more drastic the overhead becomes (because a cache validation is performed for each device).