On 07/12/2017 08:35 AM, Simone Zucchi wrote: > Well I've just managed to disable it. Seems the problem was > TRANSPARENT_HUGEPAGE flag > which selected COMPACTION which selects MIGRATION. > Great :) thanks
As migration involves a series of changes to the page table done from the (non-rt) virtual memory core, an increased rate of minor page faults taken by the rt side has been observed in the wake of those fixups, which directly translates into latency peaks. This is why CONFIG_MIGRATION is flagged as potentially raising the overall latency figures in Kconfig. This is not only a matter of dealing with large NUMA configurations though, since CONFIG_MIGRATION is also used by the memory compaction machinery, as you found out. So even on embedded systems, those peaks stand out. Granted, page migration does not cause pathological latency peaks; but those tend to get in the way nevertheless on some SoCs when Xenomai is used to drive a closed loop control software running a high frequency acquisition. -- Philippe. _______________________________________________ Xenomai mailing list [email protected] https://xenomai.org/mailman/listinfo/xenomai
