Re: [resend][PATCH] mm: increase RECLAIM_DISTANCE to 30

[KOSAKI Motohiro]

> 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.



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