On Tue, 12 Oct 2010, KOSAKI Motohiro wrote: > > It doesn't determine what the maximum latency to that memory is, it relies > > on whatever was defined in the SLIT; the only semantics of that distance > > comes from the ACPI spec that states those distances are relative to the > > local distance of 10. > > Right. but do we need to consider fake SLIT case? I know actually such bogus > slit are there. but I haven't seen such fake SLIT made serious trouble. > If we can make the assumption that the SLIT entries are truly representative of the latencies and are adhering to the semantics presented in the ACPI spec, then this means the VM prefers to do zone reclaim rather than from other nodes when the latter is 3x more costly. That's fine by me, as I've mentioned we've done this for a couple years because we've had to explicitly disable zone_reclaim_mode for such configurations. If that's the policy decision that's been made, though, we _could_ measure the cost at boot and set zone_reclaim_mode depending on the measured latency rather than relying on the SLIT at all in this case. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>