On Thu, Apr 06, 2017 at 09:34:36AM +0200, Michal Hocko wrote: > On Thu 06-04-17 12:49:50, Srikar Dronamraju wrote:
> > Similar example that I gave in my reply to Mel. > > > > Lets consider 2 node, 24 core with 12 cores in each node. > > Cores 0-11 in Node 1 and cores 12-23 in the other node. > > Lets also disable smt/hyperthreading, enable isolcpus from core > > 6-11,12-17. Lets run 48 thread ebizzy workload and give it a cpu list > > of say 11,12-17 using taskset. > > > > Now all the 48 ebizzy threads will only run on core 11. It will never > > spread to other cores even in the same node(or in the same node/but > > isolated cpus) or to the different nodes. i.e even if numabalancing is > > running or not, even if my fix is around or not, all threads will be > > confined to core 11, even though the cpus_allowed is 11,12-17. Argh, why such a convoluted example :-( > Isn't that a bug in isolcpus implementation? It is certainly an > unexpected behavior I would say. Is this documented anywhere? Without engaging the brain too much to decipher the example; it does look right. isolcpus will have no balancing. > Isn't sched_setaffinity the only way how to actually make it possible to > run on isolcpus? Think so.. Personally I hate isolcpus and never use it. > I would really like to see it confirmed by the scheduler maintainers and > documented properly as well. What you are claiming here is rather > surprising to my understanding of what isolcpus acutally is. isolcpus gets you a set of fully partitioned CPUs. What's surprising about that?
