Re: [libvirt] [PATCH v2] lib: Add note that bulk stats API queries may overrun RPC buffers

On Tue, May 23, 2017 at 17:19:53 +0200, Martin Kletzander wrote: > On Tue, May 23, 2017 at 05:07:40PM +0200, Michal Privoznik wrote: > > On 05/23/2017 04:35 PM, Martin Kletzander wrote: > > > On Tue, May 23, 2017 at 04:23:30PM +0200, Peter Krempa wrote: [...] > > > > + * Note that this API is prone to exceeding maximum RPC if querying > > > > too many VMs > > > > + * with lots of statistics. It's suggested to query in batches of > > > > 10VMs, which > > > > + * should be good enough for VMs with 3000 disks + networks. > > > > + * > > > > > > Coming to think about it... Why don't we just batch this ourselves under > > > the hood and just return the merged result? > > > > Because: > > > > https://www.redhat.com/archives/libvir-list/2017-May/msg00088.html > > > > Not on the RPC level, the API would just be syntax sugar to > virDomainListGetStats() if a flag was passed > (e.g. VIR_DOMAIN_GET_ALL_STATS_I_DONT_REALLY_CARE_IF_THIS_IS_DONE_IN_ONE_LIBVIRT_CALL) Also compared to a full fragmentation of the returned data, this would result into a worst-case-scenario memory usage of MAX_SIZE * NVMS_QUERIED_IN_ORIGINAL_CALL, when compared to an unbounded memory use of the full fragmentation approach.

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