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i7 920 With Hyper Threadding, Core Identification.

H

Hamakua

Weaksauce
Joined
Jul 26, 2009
Messages
67
Quick Q. With hyper threading on which "sets" of logical cores are the individual physical cores? :confused:

0,1 = Core 1
2,3 = Core 2
4,5 = Core 3
6,7 = Core 4

Is this right? This is in reference to most monitoring software and calls to the CPU for temperature and load.

I tried looking for any whitepapers or even a simple diagram that would identify the grouping but couldn't find any. I am sure there is some out there but I suspect it's on page 536, or 537 of one of the Google searches.

And one last, thing,

Core 1-4 would be from left to right physically with the L3 cache oriented below the cores and the IHS facing up, correct?

-Thanks in advance.

edit IHS =/ HSF
 
Last edited:
For performance it doesn't matter. Theres no "primary" cores, its just each core working on 2 threads, resources between the 2 are (to a large degree, some stuff is duplicated and not shared) dynamically allocated. The scheduler is good at using one of each physical core until theres a need for more.

For temps, well, I don't know. :( Id just look at the average anyway, unless one is reporting higher numbers. There shouldnt be 8 temp readouts anyway, just 4.
 
There's no guarantee what logical processor belongs to what core. This can change from one bios version to the next on the same computer and it can change each time you boot up.

I number the cores from 0 to 3 and the threads from 0 to 7 and what you have listed is typical for Core i7 but there's no guarantee that your Threads are numerically ordered from 0 to 7. It's up to monitoring software to query the processor to make sure what thread comes from what core.

Thread 0,1 - Core 0
Thread 2,3 - Core 1
Thread 4,5 - Core 2
Thread 6,7 - Core 3

If you use RealTemp, it will show you the order of the threads in the Settings window. It is called APIC ID.

The second most popular way I've seen is an APIC ID order of 0,2,4,6,1,3,5,7 but there are some bios versions where this order is completely scrambled. If software doesn't take this into account, it will report the core temperatures from the wrong cores and there are programs that are only reporting the core temperature from 2 cores instead of 4. When the APIC ID is 01234567, it reads the core temperatures from the first 4 threads but that completely ignores core 2 and core 3. One of the most popular monitoring programs is doing this but hardly anyone has noticed.

The other problem is that even Task Manager ignores APIC ID information so getting to the bottom of this issue can be difficult.
 
Thanks all, while I am still on the hunt for info, that was a big help. :)
 
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