On 18 Jul 2014, at 5:16 pm, Vladislav Bogdanov <bub...@hoster-ok.com> wrote:
> Hi Andrew, all, > > I have a task which seems to be easily solvable with the use of > globally-unique clone: start huge number of specific virtual machines to > provide a load to a connection multiplexer. > > I decided to look how pacemaker behaves in such setup with Dummy > resource agent, and found that handling of every instance in an > "initial" transition (probe+start) slows down with increase of clone-max. "yep" for non unique clones the number of probes needed is N, where N is the number of nodes. for unique clones, we must test every instance and node combination, or N*M, where M is clone-max. And that's just the running of the probes... just figuring out which nodes need to be probed is incredibly resource intensive (run crm_simulate and it will be painfully obvious). > > F.e. for 256 instances transition took 225 seconds, ~0.88s per instance. > After I added 768 more instances (set clone-max to 1024) together with > increasing batch-limit to 512, transition took almost an hour (3507 > seconds), or ~4.57s per added instance. Even if I take in account that > monitoring of already started instances consumes some resources, last > number seems to be rather big, > > Main CPU consumer on DC while transition is running is crmd, Its memory > footprint is around 85Mb, resulting CIB size together with the status > section is around 2Mb, You said CPU and then listed RAM... > > Could it be possible to optimize this use-case from your opinion with > minimal efforts? Could it be optimized with just configuration? Or may > it be some trivial development task, f.e replace one GList with > GHashtable somewhere? Optimize: yes, Minimal: no > > Sure I can look deeper and get any additional information, f.e. to get > crmd profiling results if it is hard to get an answer just from the head. Perhaps start looking in clone_create_probe() > > Best, > Vladislav > > _______________________________________________ > Pacemaker mailing list: Pacemaker@oss.clusterlabs.org > http://oss.clusterlabs.org/mailman/listinfo/pacemaker > > Project Home: http://www.clusterlabs.org > Getting started: http://www.clusterlabs.org/doc/Cluster_from_Scratch.pdf > Bugs: http://bugs.clusterlabs.org
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