Dual-core and single-core processors

Watch this thread
SpiralV
Badges: 7
Rep:
? You'll earn badges for being active around the site. Rep gems come when your posts are rated by other community members.
#1
Report Thread starter 7 years ago
#1
1) If a laptop's description says it has a Dual-core 1GHz processor, does that mean 2x1=2GHz? Or is it just 1GHz?

2) A laptop has a single-core 1.5GHz, and another laptop has Dual-core 1Ghz processor. If all other things about them are equal, which one is faster?

Thanks in advance for the answer.
0
reply
username612415
Badges: 21
Rep:
? You'll earn badges for being active around the site. Rep gems come when your posts are rated by other community members.
#2
Report 7 years ago
#2
(Original post by Spiral1977)
1) If a laptop's description says it has a Dual-core 1GHz processor, does that mean 2x1=2GHz? Or is it just 1GHz?

2) A laptop has a single-core 1.5GHz, and another laptop has Dual-core 1Ghz processor. If all other things about them are equal, which one is faster?

Thanks in advance for the answer.
1. The clock speed listed (the number in GHz) is the maximum clock speed, and all cores are capable of running at this speed simultaneously. Depending on the task this may or may not be necessary and certain cores may run slower or completely idle in certain CPUs, or extra power may be available if required if the CPU has technologies like Intel's Turbo Boost.

2. First and foremost avoid single core laptops like the plague- at this point of time any single core laptop is going to be a relic.

As for whether higher cores or higher clock is better, it's never that simple- I'd take a low voltage dual core i3 over a low end AMD quad core most of the time. The processor architecture, the intended uses, and other factors all play a part.
0
reply
Iqbal007
Badges: 19
Rep:
? You'll earn badges for being active around the site. Rep gems come when your posts are rated by other community members.
#3
Report 7 years ago
#3
(Original post by Spiral1977)
1) If a laptop's description says it has a Dual-core 1GHz processor, does that mean 2x1=2GHz? Or is it just 1GHz?

2) A laptop has a single-core 1.5GHz, and another laptop has Dual-core 1Ghz processor. If all other things about them are equal, which one is faster?

Thanks in advance for the answer.
As Gofre stated.

However, there are other important factors, such the architecture of the processor itself....a 3 year old dual core 2.5ghz processor against the latest 1.5ghz dual core, the 1.5ghz would win. These days its more than the clock speed, but the physical body of the processor, etc As they are more efficient and capable of processing quicker as a result.

Dual core wins, today every type of computer program can optimise dual cores so will run faster and many can use quad cores to its full extent.
0
reply
Camoxide
Badges: 14
Rep:
? You'll earn badges for being active around the site. Rep gems come when your posts are rated by other community members.
#4
Report 7 years ago
#4
Also core i3s are dual core hyper threaded which means they act like a quad core.
0
reply
ihavemooedtoday
Badges: 17
Rep:
? You'll earn badges for being active around the site. Rep gems come when your posts are rated by other community members.
#5
Report 7 years ago
#5
(Original post by Camoxide)
Also core i3s are dual core hyper threaded which means they act like a quad core.
They don't quite act like quad core.

They have a few duplicated parts that allows the OS to schedule 2 threads on each, so that when 1 thread is not using shared execution resources (eg. it has a pipeline stall), the other thread can run. In reality this usually gives ~10% increase over no HT. It's nowhere near a real quad core.
0
reply
Camoxide
Badges: 14
Rep:
? You'll earn badges for being active around the site. Rep gems come when your posts are rated by other community members.
#6
Report 7 years ago
#6
(Original post by ihavemooedtoday)
They don't quite act like quad core.

They have a few duplicated parts that allows the OS to schedule 2 threads on each, so that when 1 thread is not using shared execution resources (eg. it has a pipeline stall), the other thread can run. In reality this usually gives ~10% increase over no HT. It's nowhere near a real quad core.
Although it's not nearly as good as a true core, hyperthreading can significantly improve performance

Name:  3DMarkFS_CPU.PNG
Views: 109
Size:  35.6 KB

That's a %50 gain in physics processing with hyperthreading.
0
reply
ihavemooedtoday
Badges: 17
Rep:
? You'll earn badges for being active around the site. Rep gems come when your posts are rated by other community members.
#7
Report 7 years ago
#7
(Original post by Camoxide)
Although it's not nearly as good as a true core, hyperthreading can significantly improve performance

Image

That's a %50 gain in physics processing with hyperthreading.
Performance gain (or loss, in some rare cases) from HT is an extremely complicated topic.

It depends on a million things.

For example, better written code will benefit less, because they will be using the CPU more efficiently already. HT relies on suboptimal code (which leaves the CPU hanging) to schedule another thread to run at the same time.

Memory bandwidth or cache constrained code won't run any faster because the 2 hyper threads share the same cache and memory bus.

Code that require more work to be done when more threads are involved (things like some types of searches or encoding algorithms) may actually become slower. For example, if 2 threads require 1.2x the amount of total work to be done, it will definitely be faster on a real dual core, but quite possibly slower on HT.

From my experience writing multi-threaded code, 10-20% improvement from HT is common. Anything higher is rare.

"Up to 50% gain" doesn't mean anything. "Up to 50% gain, 2% of the time" does.

Where did you get that picture from? Link?
0
reply
X

Quick Reply

Attached files
Write a reply...
Reply
new posts
Back
to top
Latest

How did The Student Room help you with your university application?

Talking to current university students (8)
24.24%
Talking to peers going through the same thing (10)
30.3%
Speaking to student ambassadors from the universities (2)
6.06%
Speaking to staff members from universities (0)
0%
Using the personal statement builder, library or helper service (3)
9.09%
Reading articles about what steps to take (6)
18.18%
Learning about/speaking to Student Finance England (2)
6.06%
Something else (tell us in the thread) (2)
6.06%

Watched Threads

View All