Thread Question

[TubsAlwaysWins]

So just to clarify, if a CPU has 4 cores and 4 threads it has only 4 possible 'projects'? (Ex. in Cinnebench it would have 4 squares rendering instead of 8?)

[Electronics Wizardy]

you can run 8 or more, they will just be sharing time on the cpu.

[RS2007GOD]

Basicly yes. A 4c4t only runs 4 units on cinebench 4c/8t runs 8

[TubsAlwaysWins]

Just now, Electronics Wizardy said:

you can run 8 or more, they will just be sharing time on the cpu.

?

Sorry im really bad at explaining things. So my understanding of threads is sort of like cores, and some CPU's can have virtual cores. So,

A 4 Core/4 thread CPU would have 4 'cores', and a 4 core/8 thread CPU would have '8' cores?

[Electronics Wizardy]

Just now, TubsAlwaysWins said:

?

Sorry im really bad at explaining things. So my understanding of threads is sort of like cores, and some CPU's can have virtual cores. So,

A 4 Core/4 thread CPU would have 4 'cores', and a 4 core/8 thread CPU would have '8' cores?

Threads are how many things it can do at once.

 

You can switch between processes hundres of times a second, and that how your system shares time between the kernel, the drivers, the services, and your main programs.

[Electronics Wizardy]

8 minutes ago, RS2007GOD said:

Basicly yes. A 4c4t only runs 4 units on cinebench 4c/8t runs 8

You can run any number of threads in cinebench you want in the advanced settings.

[Godlygamer23]

10 minutes ago, TubsAlwaysWins said:

?

Sorry im really bad at explaining things. So my understanding of threads is sort of like cores, and some CPU's can have virtual cores. So,

A 4 Core/4 thread CPU would have 4 'cores', and a 4 core/8 thread CPU would have '8' cores?

A four core CPU with four threads would have four devices visible to the operating system. In other words, the OS would see four "cores" that it could execute tasks on. A four core CPU with eight threads would have eight devices visible to the operating system, with the OS seeing eight "cores" that it could execute tasks on. 

 

If I remember correctly, the number of devices that the OS can see is called "logical devices." In that, they may only exist in the logic of the hardware. Increasing the number of threads technically means that the operating system can execute two tasks on a core at once, but the core is still not doing two things at once. It's just rapidly switching between the tasks in each respective thread.

[SpaceGhostC2C]

1 hour ago, TubsAlwaysWins said:

?

Sorry im really bad at explaining things. So my understanding of threads is sort of like cores, and some CPU's can have virtual cores. So,

A 4 Core/4 thread CPU would have 4 'cores', and a 4 core/8 thread CPU would have '8' cores?

They aren't really like cores, though. They are more like tasks. 

 

Imagine the CPU is a kitchen. The number of cores is the number of chefs in said kitchen. Threads are orders to be executed, let's say dishes to cook. 4c/4t means the kitchen will only take orders for 4 dishes at a time, and won't take new orders until a dish is out. 4c/8t means you still have 4 cooks, but each of them can take 2 orders. He still can mostly work on a single dish, but sometimes he will be waiting for water to boil on one dish, and may start cutting vegetables for the second dish instead of just waiting. When the water boils, he can turn his attention back to the first dish. 

 

So, 4 cores are 4 cores, just like 4 cooks are 4 cooks, hyperthreading or not. It's just that HT-capable cores can keep an eye on a second task, and fill in some idle times of particular parts inside the core with work for the second task. 

Sometimes there are a lot of idle times and gains are considerable, sometimes there aren't many spare resources anyway so it doesn't matter, and sometimes, just like in the kitchen case, taking too many orders will actually harm the multi-threaded performance of a CPU. This is in contrast with physical cores (i.e., hiring more cooks), where additional cores always improve multithreaded performance.