* KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx> [2010-10-12 13:07:35]: > > 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. > > ok, got it. thanks. > Could we please document the change and help people understand why with newer kernels they may see the value of zone_reclaim_mode change on their systems and how to set it back if required. -- Three Cheers, Balbir -- 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>