Windows XP 64 and Core Usage

Started by rcallicotte, October 22, 2008, 09:27:54 AM

Previous topic - Next topic

rcallicotte

I'm showing only 1 core in xp64 and was showing 4 cores in xp32. 
So this is Disney World.  Can we live here?

Matt

I've uploaded a very simple program which reports CPU layout information on Windows: the relationships between NUMA nodes, cores, logical processors.

http://www.planetside.co.uk/terragen/downloads/cpulayout.exe

Please run that and let us know what it says.

Matt
Just because milk is white doesn't mean that clouds are made of milk.

Matt

Just because milk is white doesn't mean that clouds are made of milk.

PG

I ran this and it said "New API GetLogicalProcessorInformation is _not_ available"
Figured out how to do clicky signatures

rcallicotte

#4
What does this mean?

If it helps, I have an Intel Core2 Quad - Q6600 @2.4GHz.
So this is Disney World.  Can we live here?

Matt

#5
Calico, this is saying that it sees 4 logical processors, but that they all share the same core (i.e. that they are hyperthreads). This is due to a shortcoming in the OS, reporting the incorrect relationship between these logical processors which really should be separate cores. I still don't know which Microsoft patches or hotfixes would correct this problem (if any). It's said that Vista gets it right but other OSs don't. It may be that your XP32 didn't run into this problem because it didn't even have these API functions at all, so Terragen would have defaulted to just treating any logical processor as a potentially useful processing core.

Matt
Just because milk is white doesn't mean that clouds are made of milk.

rcallicotte

Thank you, Matt.  I changed the setting in TG2 to see 4 cores and haven't noticed a problem since.  It's only been this week, though, so I hate to be over-optimistic.  Or should I worry?
So this is Disney World.  Can we live here?

Matt

If you choose to override the number of cores, then it doesn't matter how Terragen detects the number or cores :)  You could also experiment with different numbers to see what gives the best render times, but efficiency should improve for higher numbers in future versions.

Matt
Just because milk is white doesn't mean that clouds are made of milk.

DarkNemos

Calico or matt,

I have the same problem with seeing one core only. So how can i overide that in TG2?

Calico sad that he did that in TG but i havent been able to find that option.



Oshyan

#9
You can change the number of cores TG will use in one of 2 places, depending on whether you want it to be permanent, or scene-dependent. To change it permanently, so that all new/default scenes will use the chosen number of cores, go to Edit->Preferences->Startup and turn on Override Automatic Number of Cores Detection. To change it just for a given renderer, go to the Advanced tab of your Renderer and set Minimum Threads appropriately. Keep in mind that if you have more than 4 threads you might not get any notable speed increase by using more than 4.

- Oshyan