Hi Wei, On 04/23/2018 10:09 PM, Wei Liu wrote: > On Sat, Apr 07, 2018 at 07:25:53PM +0800, Dongli Zhang wrote: >> About per-domU xenwatch thread create/destroy, a new type of xenstore node is >> introduced: '/local/domain/0/mtwatch/<domid>'. >> >> Suppose the new domid id 7. During the domU (domid=7) creation, the xen >> toolstack writes '/local/domain/0/mtwatch/7' to xenstore before the insertion >> of '/local/domain/7'. When the domid=7 is destroyed, the last xenstore >> operation by xen toolstack is to remove '/local/domain/0/mtwatch/7'. >> >> The dom0 kernel subscribes a watch at node '/local/domain/0/mtwatch'. Kernel >> thread [xen-mtwatch-7] is created when '/local/domain/0/mtwatch/7' is >> inserted, >> while this kernel thread is destroyed when the corresponding xenstore node is >> removed. > > Instead of inventing yet another node, can you not watch /local/domain > directly?
Would you like to watch at /local/domain directly? Or is your question "is there any other way to not watch at /local/domain, while no extra xenstore node will be introduced"? Actually, the first prototype of this idea was to watch at /local/domain directly to get aware of the domU create/destroy, so that xen toolstack will not get involved. Joao Martins (CCed) had a concern on the performance as watching at /local/domain would lead to large amount of xenwatch events. Dongli Zhang