[Fallen Angel -X]

Yo

Is it true that, cpus can actually only do 1 thing at once,

and just give the illusion of multitasking?

 

[RonindeBeatrice]

In short, yes. They just happen to finish them very quickly.

 

[Penryn]

1 thing per core per clock cycle.

 

[Markus]

CPUs can do several things at once, so the statement that cpus actually only can do 1 thing at once is wrong.

Edit: Someone please explain to me why they wouldn't be able to do more than 1 thing at a time ?

 

[Wingzero]

No quad cores can do 4.

 

[flashbulb]

modern cpus do multiple operations per clock, and they do those operations billions of times per second

 

[NameUnknown]

I single CPU Core can only perform 1 task per clock cycle. Now it just happens that there are 4 billion of those things done every second on each core a processor OC'd to 4.0GHz.

So if you have a dual core you can do 2 tasks, a tricore 3 tasks, a quad 4 tasks, a hexacore 6 tasks. All of these are per clock cycle. Multiply by X.X billion according to your CPU speed in gigahertz to found out how many per second.

Hyperthreading enables a single core to analyze and process two threads simultaneously, this it is able to do 4 threads on a dual core in 1 clock cycle and so on for quads and hexes.

 

[RonindeBeatrice]

Quote:

Originally Posted by Markus CPUs can do several things at once, so the statement that cpus actually only can do 1 thing at once is wrong. Edit: Someone please explain to me why they wouldn't be able to do more than 1 thing at a time ?

CPUs may be able to perform multiple instructions in a single cycle, but this is the handy work of the scheduler and predictive units which recognize that part of the instruction pipeline won't be used. The instruction pipeline is a straight tube. Info goes in one end, comes out the other all computed.

http://en.wikipedia.org/wiki/Branch_predictor

 

[FtW 420]

Would also depends how much memory the applications are using I think.

 

[Boatski]

GPU's can do multiple things at once unlike CPU's!

 

[KILLER_K]

Single core would be like one guy with a bucket carrying water.
Dual core would be like 2 guys with 2 buckets carrying water.
Triple core would be three guys with 3 buckets carrying water.
Quad core would be 4 guys with four buckets carrying water.

If you add HT into the mix each guy will have two buckets each carrying water. So a quad core with Ht would be 4 guys carrying two buckets each, so 8 buckets going then.

More cores and HT the faster you can use the buckets of water.

 

[Kokin]

Quote:

Originally Posted by Boatski GPU's can do multiple things at once unlike CPU's!

It's like you never read the whole thread and just answered something random for post counts or are you just trolling?

BTW, for hyperthreading, it's not a full core, so the second thread actually waits for the first thread to finish it's job before it can become active and vice-versa.

 

[AK-47]

Quote:

Originally Posted by Fallen Angel -X Yo Is it true that, cpus can actually only do 1 thing at once, and just give the illusion of multitasking?

In theory yes they only do 1 thing at once but they switch back and forth so fast you never notice it.

 

[Penryn]

To put it simply, depending on the task, a cpu can do more than one thing at a time which is limited by the instruction set in use. For example, an i7 980x can do about 50 instructions per clock cycle. This puts it at about 150,000 million instructions per second at 3.3ghz. Not too shabby. But code is written to use these cycles up pretty well. This is also how we see CPU usage.

Edited for maths.

 

[RonindeBeatrice]

Quote:

Originally Posted by http://www.tomshardware.com/reviews/Intel-i7-nehalem-cpu,2041-3.html Nehalem... is still capable of macro-ops fusion and so offers a theoretical maximum throughput of 4+1 x86 instructions per cycle.

While this means that the nehalem can do 5 things at once, it is only capable of producing the results of those operations one a cycle.

 

[Penryn]

Quote:

Originally Posted by RonindeBeatrice what?! no, just no.

Fixt.

 

[chatch15117]

Quote:

Originally Posted by Penryn 1 thing per core per clock cycle.

Actually there are multiple instructions executed per clock cycle, even on single core and single threaded cpus.

http://en.wikipedia.org/wiki/Instructions_per_cycle

 

[Penryn]

Quote:

Originally Posted by chatch15117 Actually there are multiple instructions executed per clock cycle, even on single core and single threaded cpus. http://en.wikipedia.org/wiki/Instructions_per_cycle

Yea, I elaborated that in my most recent post. 1 thing per clock cycle at its most basic. Depends on the processor though. i7 980x = 50 instructions per clock cycle, 150,000 million per second at 3.3Ghz. This equals roughly 4 instructions per thread per clock cycle. 13,000 million per thread per second.

 

[RonindeBeatrice]

Quote:

Originally Posted by Penryn Fixt.

that 50 instructions per cycle is the simple product of the 980 having 6 cores.

One core, one cycle, one output.

Billions of times a second. It's really simple.

Hyperthreading further increases this by

Quote:

Hyper-threading works by duplicating certain sections of the processor... This allows a hyper-threading processor to appear as two "logical" processors to the host operating system,

 

[chatch15117]

Quote:

Originally Posted by Penryn Yea, I elaborated that in my most recent post. 1 thing per clock cycle at its most basic. Depends on the processor though. i7 980x = 50 instructions per clock cycle, 150,000 million per second at 3.3Ghz. This equals roughly 4 instructions per thread per clock cycle. 13,000 million per thread per second.

You should have edited the first post then. I posted that wiki link for a reason