[miacomet]

So Activity monitor measures CPU Usage in a nifty little rolling series of green and red dots piled on top of each other to measure the amount of CPU usage. It looks a little bit like a stock ticker.

On systems with more than one core, it has one of these CPU usage graphs for each core.

See: OS X: Activity Monitor shows one CPU Usage graph on systems with more than four cores

But my 15" rMBP i7 with 4 cores only shows one graph in the activity monitor.
And my 11" MBA i7 with 2 cores shows four graphs in the activity monitor.

Can anyone explain to me what is the reason for this discrepancy? Thanks!

[P]

Both your Macs have Hyperthreading, a feature that makes each processor core appear as two to the operating system. To the operating system, your 11" MBA has 4 cores and your MBP has 8. Presumably Activity Monitor defaults to only showing one graph when you have 8 cores, because it would confusing otherwise. There's probably a setting to override it in one of the menus.

[miacomet]

Ah, ha. THX!!!

[Waragainstsleep]

My 8 core Xserve shows all 8 cores.