Messages in this thread | | | Subject | Re: [Xen-devel] [RFC 0/2] To introduce xenwatch multithreading (xen mtwatch) | From | Juergen Gross <> | Date | Tue, 24 Apr 2018 08:03:18 +0200 |
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On 24/04/18 07:52, Dongli Zhang wrote: > Hi Juergen, > > On 04/24/2018 01:22 PM, Juergen Gross wrote: >> On 24/04/18 01:55, Dongli Zhang wrote: >>> 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. >> >> That's what the special watches "@introduceDomain" and "@releaseDomain" >> are meant for. > > I used to consider to watch at "@introduceDomain". However, there is no domain > information appended with "@introduceDomain" and it is still required for dom0 > kernel to proactively confirm who is created.
That isn't too hard, right? You just need to read /local/domain to get the list of its children and look for new domains there.
Juergen
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