More instructions per clock cycle, or faster clockspeed?

GEC: Discuss gaming, computers and electronics and venture into the bizarre world of STGODs.

Moderator: Thanas

Post Reply
Kreshna Aryaguna Nurzaman
Jedi Council Member
Posts: 2230
Joined: 2002-07-08 07:10am

More instructions per clock cycle, or faster clockspeed?

Post by Kreshna Aryaguna Nurzaman »

AMD and Intel each follows different paths in developing their processor. AMD aims for more instructions per clock cycle, while Intel goes for faster clock speed.

(1) Since AMD processors are capable of executing more instructions per cycle, why not creating them with clockspeed equalling those of Intel? Is there a design trade-off between the two? Or it's just a matter of cost?

(2) What are the positives and negatives of each approach?

(3) So far AMD processors soar in applications like games, while Intel has better performance (IIRC) in multitasked environments and content creations. Does it somehow relate to each different approach above?

(4) What kind of applications would benefit more from more instructions per cycle, and which ones would benefit more from faster clockspeed?
User avatar
phongn
Rebel Leader
Posts: 18487
Joined: 2002-07-03 11:11pm

Re: More instructions per clock cycle, or faster clockspeed?

Post by phongn »

Kreshna Aryaguna Nurzaman wrote:AMD and Intel each follows different paths in developing their processor. AMD aims for more instructions per clock cycle, while Intel goes for faster clock speed.
Look, KAN. You don't need to bold anything. Frankly, it makes it more difficult to read your posts and is marginally annoying. We are perfectly capable of reading, thank you.
Since AMD processors are capable of executing more instructions per cycle, why not creating them with clockspeed equalling those of Intel? Is there a design trade-off between the two? Or it's just a matter of cost?
It is a design tradeoff.
What are the positives and negatives of each approach?
Intel's process technology is extremely good so they predicted that they could continue to scale the Netburst core to very high clockspeeds to compenstate for its inferior IPC. For awhile this worked until they hit a wall around the 90nm mark (which nobody predicted).

AMD decided to try and get the most work out. However, such designs do not scale clockspeed-wise as easily so they have to worry about the competition ramping up the clock too quickly.
So far AMD processors soar in applications like games, while Intel has better performance (IIRC) in multitasked environments and content creations. Does it somehow relate to each different approach above?
There's a correlation. The P4's superiority in multitasking comes more from its ability to efficiently fill the instruction pipeline courtesy of SMT. In addition, its high clockspeed coupled with its SIMD core means that it can move data very quickly, which is useful for things like content creation.

AMD processors simply do out a lot of general-purpose work efficiently, so it performs well there. If the K8 was unable to scale, however, then the P4 would be superior anyways.
What kind of applications would benefit more from more instructions per cycle, and which ones would benefit more from faster clockspeed?
Yes.
User avatar
Xon
Sith Acolyte
Posts: 6206
Joined: 2002-07-16 06:12am
Location: Western Australia

Post by Xon »

How fast the clock cycle is or how much instructions per clock cycle(IPC), isnt the problem. It is how many instructions per second (clock cycle * instructions per clock cycle) which determine how much "work" is done.

And doing "work" will involve a waste heat. Which under modern CPUs, is a crapload.

Which is why you dont see high IPC and ultra high clock cycles. The waste heat starts causing massive problems, as well as other issues with getting it to pump that amount of energy around.
"Okay, I'll have the truth with a side order of clarity." ~ Dr. Daniel Jackson.
"Reality has a well-known liberal bias." ~ Stephen Colbert
"One Drive, One Partition, the One True Path" ~ ars technica forums - warrens - on hhd partitioning schemes.
User avatar
Mr Bean
Lord of Irony
Posts: 22442
Joined: 2002-07-04 08:36am

Post by Mr Bean »

I should toss in here quick note new AMD Dual cores depending on test setup(Limiters, applications used) are either loosing by a inch, winning by an inch or curbstomping the Pentium IV

That said I must also note Tom's Hardwares recent tests of the Pentium M, which sure as hell shocked me

+http://www.tomshardware.com/cpu/20050525/index.html

Specificly this page
+http://www.tomshardware.com/cpu/2005052 ... m4-10.html

Its not everyday you see a 2.5Ghtz proccesor stomp ever faster AMD and Pentium IV proccesors so well.

Note these were the new(And aviable) Pentium M's overclocked to 2.5Gthz, a Ghtz slower than Intel's Faster's PIV's

"A cult is a religion with no political power." -Tom Wolfe
Pardon me for sounding like a dick, but I'm playing the tiniest violin in the world right now-Dalton
User avatar
Arrow
Jedi Council Member
Posts: 2283
Joined: 2003-01-12 09:14pm

Post by Arrow »

A couple of other important factors are what instructions are you trying to execute (do your results come back in a single clock cycle or multiple cycles), and compiler efficiency (how well the code can take advantage of the processor's features). Ramping up your clock speed or adding additional execution units isn't going automatically increase your program's speed - it really depends on CPU's overall architecture.
Artillery. Its what's for dinner.
User avatar
Ace Pace
Hardware Lover
Posts: 8456
Joined: 2002-07-07 03:04am
Location: Wasting time instead of money
Contact:

Post by Ace Pace »

Mr Bean wrote:I should toss in here quick note new AMD Dual cores depending on test setup(Limiters, applications used) are either loosing by a inch, winning by an inch or curbstomping the Pentium IV

That said I must also note Tom's Hardwares recent tests of the Pentium M, which sure as hell shocked me

+http://www.tomshardware.com/cpu/20050525/index.html

Specificly this page
+http://www.tomshardware.com/cpu/2005052 ... m4-10.html

Its not everyday you see a 2.5Ghtz proccesor stomp ever faster AMD and Pentium IV proccesors so well.

Note these were the new(And aviable) Pentium M's overclocked to 2.5Gthz, a Ghtz slower than Intel's Faster's PIV's
Yes I was going to post that somewhere, if they keep this preformance up with their new core in 2006, theres not going to be a reason to buy anything desktop, just boot the laptop and somehow get a high end graphics card into it.
Brotherhood of the Bear | HAB | Mess | SDnet archivist |
User avatar
Einhander Sn0m4n
Insane Railgunner
Posts: 18630
Joined: 2002-10-01 05:51am
Location: Louisiana... or Dagobah. You know, where Yoda lives.

Post by Einhander Sn0m4n »

Ace Pace wrote:
Mr Bean wrote:I should toss in here quick note new AMD Dual cores depending on test setup(Limiters, applications used) are either loosing by a inch, winning by an inch or curbstomping the Pentium IV

That said I must also note Tom's Hardwares recent tests of the Pentium M, which sure as hell shocked me

+http://www.tomshardware.com/cpu/20050525/index.html

Specificly this page
+http://www.tomshardware.com/cpu/2005052 ... m4-10.html

Its not everyday you see a 2.5Ghtz proccesor stomp ever faster AMD and Pentium IV proccesors so well.

Note these were the new(And aviable) Pentium M's overclocked to 2.5Gthz, a Ghtz slower than Intel's Faster's PIV's
Yes I was going to post that somewhere, if they keep this preformance up with their new core in 2006, theres not going to be a reason to buy anything desktop, just boot the laptop and somehow get a high end graphics card into it.
Then we'll be seeing laptops with little neutrino-radiators that flip out of the wings in combat mode :lol: :lol:
Image Image
User avatar
Ace Pace
Hardware Lover
Posts: 8456
Joined: 2002-07-07 03:04am
Location: Wasting time instead of money
Contact:

Post by Ace Pace »

Actully if you finshed reading the article, you would have noticed that thing is COLD.
Brotherhood of the Bear | HAB | Mess | SDnet archivist |
User avatar
Mr Bean
Lord of Irony
Posts: 22442
Joined: 2002-07-04 08:36am

Post by Mr Bean »

Ace Pace wrote:Actully if you finshed reading the article, you would have noticed that thing is COLD.
To the tune of ten to thirty degrees colder depending on the speed/preformance

"A cult is a religion with no political power." -Tom Wolfe
Pardon me for sounding like a dick, but I'm playing the tiniest violin in the world right now-Dalton
User avatar
Ace Pace
Hardware Lover
Posts: 8456
Joined: 2002-07-07 03:04am
Location: Wasting time instead of money
Contact:

Post by Ace Pace »

Mr Bean wrote:
Ace Pace wrote:Actully if you finshed reading the article, you would have noticed that thing is COLD.
To the tune of ten to thirty degrees colder depending on the speed/preformance
Yes, while the newer AMD's(which if you notice,were NOT benched here), are allmost as cold as the Pentium M's(Source here)

The big kicker is graphic chipss, with the Pentium M's DDR2 RAM being colder, but the moment any rig runs a high end card, power\heat double.
Brotherhood of the Bear | HAB | Mess | SDnet archivist |
Ypoknons
Jedi Knight
Posts: 999
Joined: 2003-05-13 06:02am
Location: Manhattan (school year), Hong Kong (vacations)
Contact:

Post by Ypoknons »

Ace Pace wrote:Yes I was going to post that somewhere, if they keep this preformance up with their new core in 2006, theres not going to be a reason to buy anything desktop, just boot the laptop and somehow get a high end graphics card into it.
If Yonah or its sucessors is that good, we'll being seeing a lot more of this:

Image
AOpen's i915GMm-HFS Pentium-M motherboard and retail shipping box.

Hasn't Intel expressed interest into moving the Pentium M architure into the desktop arena anyways? Though to be fair overclocked Pentium M's should be compared to overclocked Athlon 64's in theory. The heat difference isn't all that big.
User avatar
Ace Pace
Hardware Lover
Posts: 8456
Joined: 2002-07-07 03:04am
Location: Wasting time instead of money
Contact:

Post by Ace Pace »

Intel has made some noise about bringing the Pentium M into the desktop, but no real steps, finding Pentium M's in retail is still hard, same with motherboards.

Another thing that could hurt retail sails is that the Pentium M is harder to install, no heat spreader = easier to break the CPU by acident,
Brotherhood of the Bear | HAB | Mess | SDnet archivist |
Kreshna Aryaguna Nurzaman
Jedi Council Member
Posts: 2230
Joined: 2002-07-08 07:10am

Re: More instructions per clock cycle, or faster clockspeed?

Post by Kreshna Aryaguna Nurzaman »

phongn wrote:Look, KAN. You don't need to bold anything. Frankly, it makes it more difficult to read your posts and is marginally annoying. We are perfectly capable of reading, thank you.
Sorry.


phongn wrote: It is a design tradeoff.

.............................................

AMD decided to try and get the most work out. However, such designs do not scale clockspeed-wise as easily so they have to worry about the competition ramping up the clock too quickly.
I see. So putting more instruction per cycle is inherently contradictive with raising the clockspeed, am I correct? And why? Is it something related to the length of the pipeline?


phongn wrote:There's a correlation. The P4's superiority in multitasking comes more from its ability to efficiently fill the instruction pipeline courtesy of SMT. In addition, its high clockspeed coupled with its SIMD core means that it can move data very quickly, which is useful for things like content creation.

AMD processors simply do out a lot of general-purpose work efficiently, so it performs well there. If the K8 was unable to scale, however, then the P4 would be superior anyways.
I remember reading somewhere about branch prediction; that AMD processors excel in applications require large amount of branches (like games). Is it correct?


ggs wrote:How fast the clock cycle is or how much instructions per clock cycle(IPC), isnt the problem. It is how many instructions per second (clock cycle * instructions per clock cycle) which determine how much "work" is done.

And doing "work" will involve a waste heat. Which under modern CPUs, is a crapload.

Which is why you dont see high IPC and ultra high clock cycles. The waste heat starts causing massive problems, as well as other issues with getting it to pump that amount of energy around.
I guess it explains why AMD processors are more susceptible to heat despite being clocked at lower GHz, doesn't it?
User avatar
Lord Zentei
Space Elf Psyker
Posts: 8742
Joined: 2004-11-22 02:49am
Location: Ulthwé Craftworld, plotting the downfall of the Imperium.

Post by Lord Zentei »

Welcome back, dude. ;)
CotK <mew> | HAB | JL | MM | TTC | Cybertron

TAX THE CHURCHES! - Lord Zentei TTC Supreme Grand Prophet

And the LORD said, Let there be Bosons! Yea and let there be Bosoms too!
I'd rather be the great great grandson of a demon ninja than some jackass who grew potatos. -- Covenant
Dead cows don't fart. -- CJvR
...and I like strudel! :mrgreen: -- Asuka
Ypoknons
Jedi Knight
Posts: 999
Joined: 2003-05-13 06:02am
Location: Manhattan (school year), Hong Kong (vacations)
Contact:

Post by Ypoknons »

Ace Pace wrote:Another thing that could hurt retail sails is that the Pentium M is harder to install, no heat spreader = easier to break the CPU by acident,
Possibily. Was this a factor back in the K7 days?
User avatar
Ace Pace
Hardware Lover
Posts: 8456
Joined: 2002-07-07 03:04am
Location: Wasting time instead of money
Contact:

Post by Ace Pace »

Not sure, I wasn't exactly in computers back then...
Brotherhood of the Bear | HAB | Mess | SDnet archivist |
User avatar
Arthur_Tuxedo
Sith Acolyte
Posts: 5637
Joined: 2002-07-23 03:28am
Location: San Francisco, California

Post by Arthur_Tuxedo »

Ypoknons wrote:
Ace Pace wrote:Another thing that could hurt retail sails is that the Pentium M is harder to install, no heat spreader = easier to break the CPU by acident,
Possibily. Was this a factor back in the K7 days?
Yes. I was terrified the first time I installed a Duron. I didn't break it, but it felt like I had to put a tremendous amount of force to get it in place, and I had just read a bunch of horror stories about people cracking their cores.
"I'm so fast that last night I turned off the light switch in my hotel room and was in bed before the room was dark." - Muhammad Ali

"Dating is not supposed to be easy. It's supposed to be a heart-pounding, stomach-wrenching, gut-churning exercise in pitting your fear of rejection and public humiliation against your desire to find a mate. Enjoy." - Darth Wong
Post Reply