4 ms·

I would say that folding is not a consequence of SMT, but of the assignment between the VP (virtual processors) assigned to the LPAR (VM) and the processing uni

I would say that folding is not a consequence of SMT, but of the assignment between the VP (virtual processors) assigned to the LPAR (VM) and the processing units assigned. So more a effect resulting from the virtualization with consequences in conjunction with SMT.

newman314 5y ago
Furthermore, the folding behavior can be adjusted. From the second link that I posted: In addition to the reduction of VPs, you can consider setting the schedo tunable “vpm_throughput_mode” to a value of 2. By default, running in raw throughput mode (i.e. vpm_throughput_mode=0) AIX spreads all available work across as many VPs as available, dispatching work first to the primary SMT thread of each VP, then the secondary SMT threads, and so on, thus providing the best performance in most workloads. This configuration, however, can lead to a higher PC (processor capacity) utilized by the LPAR. Depending the workload, you can reduce the PC by setting the vpm_throughput_mode tunable to 2, thus having AIX to schedule work to the primary and secondary threads equally.