On Fri, 13 Mar 2015, David Rientjes wrote: > It would be really disappointing to not enable this by default for !rt > kernels. We haven't migrated mlocked pages in the past by way of memory > compaction because it can theoretically result in consistent minor page > faults, but I haven't yet heard a !rt objection to enabling this. > > If the rt patchset is going to carry a patch to disable this, then the > question arises: why not just carry an ISOLATE_UNEVICTABLE patch instead? > I think you've done the due diligence required to allow this to be > disabled at any time in a very easy way from userspace by the new tunable. > I think it should be enabled and I'd be very surprised to hear any other > objection about it other than it's different from the status quo. Compaction can alrady be disabled and thus you can also disable migration of mlocked pages. In general low latency requires that no expensive kernel processing is being done. Thus the rest of compaction processing also needs to be disabled. That means that allowing compaction handling mlocked pages would be ok. RT loads and low latency configurations (like my environment) will selective disable compaction to avoid creating additional latencies. This could be done only for specific nodes and processors if necessary. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>