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#16
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Should Core 2 Duo CPU not be theoretically slower than single core with double MHz?
Jason Stacy wrote:
When I run the same application on a two core system then it can occupy only ONE of the two cores with 1.7 MHz. Because it is non-threaded it cannot request the other core as well. So it must be slower (given all other side-conditions are equal). Am I wrong? Yes. You were wrong to cross-post to two groups while setting a follow-up to only one of them. But regarding your CPU question, "everything else equal" you are correct. Why ask such an obvious question? Just as obviously, if the CPU's are entirely different designs, or have different amounts of cache, etc, then you no longer have that simple "everything else equal" question. |
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#17
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Should Core 2 Duo CPU not be theoretically slower than single core with double MHz?
Jason Stacy wrote:
When I run the same application on a two core system then it can occupy only ONE of the two cores with 1.7 MHz. Because it is non-threaded it cannot request the other core as well. So it must be slower (given all other side-conditions are equal). Am I wrong? Yes. You were wrong to cross-post to two groups while setting a follow-up to only one of them. But regarding your CPU question, "everything else equal" you are correct. Why ask such an obvious question? Just as obviously, if the CPU's are entirely different designs, or have different amounts of cache, etc, then you no longer have that simple "everything else equal" question. |
#18
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Should Core 2 Duo CPU not be theoretically slower than single core with double MHz?
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#19
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Should Core 2 Duo CPU not be theoretically slower than single core with double MHz?
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#20
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Should Core 2 Duo CPU not be theoretically slower than single core with double MHz?
If we previously had Pentium 3.8Ghz processors, then why can't they just
make 3.8Ghz dual or quad core processors? Why are they always at such low speeds? Is size really a factor? Can't they just make the chips an inch or two larger to accomodate or will heat be the issue? "Jason Stacy" wrote in message ... I wonder why a two-core CPU with lets say 2 * 1.7 Mhz is theoretically faster than a single core with 3.4 MHz. I am NOT talking about additional features like Pipeling and Hyperthreading but the core fact that the power is split over two cores. Assume the following situation: A NON-THREADED application needs as much CPU power as possible for some computations. On a 3.4 Mhz machine it can occupied almost 99% of the CPU power (remaining 1 % are for system services). When I run the same application on a two core system then it can occupy only ONE of the two cores with 1.7 MHz. Because it is non-threaded it cannot request the other core as well. So it must be slower (given all other side-conditions are equal). Am I wrong? J. |
#21
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Should Core 2 Duo CPU not be theoretically slower than single core with double MHz?
If we previously had Pentium 3.8Ghz processors, then why can't they just
make 3.8Ghz dual or quad core processors? Why are they always at such low speeds? Is size really a factor? Can't they just make the chips an inch or two larger to accomodate or will heat be the issue? "Jason Stacy" wrote in message ... I wonder why a two-core CPU with lets say 2 * 1.7 Mhz is theoretically faster than a single core with 3.4 MHz. I am NOT talking about additional features like Pipeling and Hyperthreading but the core fact that the power is split over two cores. Assume the following situation: A NON-THREADED application needs as much CPU power as possible for some computations. On a 3.4 Mhz machine it can occupied almost 99% of the CPU power (remaining 1 % are for system services). When I run the same application on a two core system then it can occupy only ONE of the two cores with 1.7 MHz. Because it is non-threaded it cannot request the other core as well. So it must be slower (given all other side-conditions are equal). Am I wrong? J. |
#22
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Should Core 2 Duo CPU not be theoretically slower than singlecore with double MHz?
shawn wrote:
If we previously had Pentium 3.8Ghz processors, then why can't they just make 3.8Ghz dual or quad core processors? Why are they always at such low speeds? Is size really a factor? Can't they just make the chips an inch or two larger to accomodate or will heat be the issue? Heat is a BIG issue. The Pentium IV (4) was the last to really push the speed barrier. Most newer systems are now into multiple cores to achieve the improved speed. There are many factors... (a) The die area and manufactured size. Back in the day most were 90nm or larger. Today 65nm and 45nm processes are available. Also, die area is expensive and the larger the die the more of a chance for bad yields. (b) The package or size you see on the outside is not always the same size the CPU chip is on the inside. Another trick would be to efficiently transfer the heat to the surface of the chip from the die. In most CPUs I've seen that is what that little square in the middle is doing for you. Then to efficiently transfer the heat from the square to the heat sink. Making the square bigger may not be a really good option; only so much and you may encounter breakage to the die underneath and/or making a well where the heat gets concentrated instead of dissipated. (c) It would probably be more than an inch or two to get the needed cooling. The ridiculous power usage is incredible on many of these new systems. I use to be able to run a FULL TOWER on a 200-watt or 250-watt power supply. Some systems today supply 900-watt or more!!! In my opinion that is a lot of power for a PC. James |
#23
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Should Core 2 Duo CPU not be theoretically slower than singlecore with double MHz?
shawn wrote:
If we previously had Pentium 3.8Ghz processors, then why can't they just make 3.8Ghz dual or quad core processors? Why are they always at such low speeds? Is size really a factor? Can't they just make the chips an inch or two larger to accomodate or will heat be the issue? Heat is a BIG issue. The Pentium IV (4) was the last to really push the speed barrier. Most newer systems are now into multiple cores to achieve the improved speed. There are many factors... (a) The die area and manufactured size. Back in the day most were 90nm or larger. Today 65nm and 45nm processes are available. Also, die area is expensive and the larger the die the more of a chance for bad yields. (b) The package or size you see on the outside is not always the same size the CPU chip is on the inside. Another trick would be to efficiently transfer the heat to the surface of the chip from the die. In most CPUs I've seen that is what that little square in the middle is doing for you. Then to efficiently transfer the heat from the square to the heat sink. Making the square bigger may not be a really good option; only so much and you may encounter breakage to the die underneath and/or making a well where the heat gets concentrated instead of dissipated. (c) It would probably be more than an inch or two to get the needed cooling. The ridiculous power usage is incredible on many of these new systems. I use to be able to run a FULL TOWER on a 200-watt or 250-watt power supply. Some systems today supply 900-watt or more!!! In my opinion that is a lot of power for a PC. James |
#24
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Should Core 2 Duo CPU not be theoretically slower than singlecore with double MHz?
shawn wrote:
If we previously had Pentium 3.8Ghz processors, then why can't they just make 3.8Ghz dual or quad core processors? Why are they always at such low speeds? Is size really a factor? Can't they just make the chips an inch or two larger to accomodate or will heat be the issue? This is a question best asked in a computer architecture group, as there are multiple factors at work. ******* Much has changed over the years. The Prescott generation was the last generation with what appeared to be a serious leakage problem. 25% of the power used, was just wasted, and did no useful work. This could not continue. The switch to 65 or 45 or 32nm could not fix the leakage issue, which would only get worse. With each generation, the transistors had to be redesigned, the material science changed, to make the scaling of the transistor worthwhile. If a Prescott transistor was just made smaller, there'd be a smoking hole in the ground. As I understand it, more complicated structures are used now for the gates. Some transistor structures have stuff added, to reduce or eliminate leakage. When absolute speed is needed, perhaps a small percentage of the structures still leak, in the interest of getting the most speed. So they pick and choose, in the interest of reducing the leakage of the processor to manageable levels. I think they've done an admirable job, based on my own power measurements (my 65W processor uses 36W max, on a 65nm Core2 Duo). The pipeline length on the new processors is shorter. They really couldn't continue on the "Prescott" path, because AMD was kicking their ass. The result is lower frequency shorter pipeline able to retire more instructions per clock cycle (parallelism inside a core) multiple cores (only really impressive, for software that uses it well) The thing is, technology exists to do really silly things, but for the retail price point, you'd be saying "no thanks, I'd rather buy a car". The current delivered technology is cheap and powerful, so stop complaining :-) Technology exists that can run at 40GHz. You could build a processor with it (if say, you had a bar bet with a buddy). No memory subsystem could reasonably supply it with information. But it would make a great room heater. (In the following article, some of the references to frequency, are for Ft of the transistor. It takes multiple transistors to make a flip-flop storage element. And the operating frequency of one of those, will be lower than the numbers seen in this article. This is just to show that there is stuff other than CMOS available to build circuits. The fiber optics criss-crossing the nation, rely on some of the following technology, to work at incredible speeds.) http://en.wikipedia.org/wiki/Heteroj...lar_Transistor http://www.ntt.co.jp/news/news06e/0609/060929a.html "InP ICs, which can be operated at over 50 GHz were used in multiplex and demultiplex circuits..." HTH, Paul "Jason Stacy" wrote in message ... I wonder why a two-core CPU with lets say 2 * 1.7 Mhz is theoretically faster than a single core with 3.4 MHz. I am NOT talking about additional features like Pipeling and Hyperthreading but the core fact that the power is split over two cores. Assume the following situation: A NON-THREADED application needs as much CPU power as possible for some computations. On a 3.4 Mhz machine it can occupied almost 99% of the CPU power (remaining 1 % are for system services). When I run the same application on a two core system then it can occupy only ONE of the two cores with 1.7 MHz. Because it is non-threaded it cannot request the other core as well. So it must be slower (given all other side-conditions are equal). Am I wrong? J. |
#25
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Should Core 2 Duo CPU not be theoretically slower than singlecore with double MHz?
shawn wrote:
If we previously had Pentium 3.8Ghz processors, then why can't they just make 3.8Ghz dual or quad core processors? Why are they always at such low speeds? Is size really a factor? Can't they just make the chips an inch or two larger to accomodate or will heat be the issue? This is a question best asked in a computer architecture group, as there are multiple factors at work. ******* Much has changed over the years. The Prescott generation was the last generation with what appeared to be a serious leakage problem. 25% of the power used, was just wasted, and did no useful work. This could not continue. The switch to 65 or 45 or 32nm could not fix the leakage issue, which would only get worse. With each generation, the transistors had to be redesigned, the material science changed, to make the scaling of the transistor worthwhile. If a Prescott transistor was just made smaller, there'd be a smoking hole in the ground. As I understand it, more complicated structures are used now for the gates. Some transistor structures have stuff added, to reduce or eliminate leakage. When absolute speed is needed, perhaps a small percentage of the structures still leak, in the interest of getting the most speed. So they pick and choose, in the interest of reducing the leakage of the processor to manageable levels. I think they've done an admirable job, based on my own power measurements (my 65W processor uses 36W max, on a 65nm Core2 Duo). The pipeline length on the new processors is shorter. They really couldn't continue on the "Prescott" path, because AMD was kicking their ass. The result is lower frequency shorter pipeline able to retire more instructions per clock cycle (parallelism inside a core) multiple cores (only really impressive, for software that uses it well) The thing is, technology exists to do really silly things, but for the retail price point, you'd be saying "no thanks, I'd rather buy a car". The current delivered technology is cheap and powerful, so stop complaining :-) Technology exists that can run at 40GHz. You could build a processor with it (if say, you had a bar bet with a buddy). No memory subsystem could reasonably supply it with information. But it would make a great room heater. (In the following article, some of the references to frequency, are for Ft of the transistor. It takes multiple transistors to make a flip-flop storage element. And the operating frequency of one of those, will be lower than the numbers seen in this article. This is just to show that there is stuff other than CMOS available to build circuits. The fiber optics criss-crossing the nation, rely on some of the following technology, to work at incredible speeds.) http://en.wikipedia.org/wiki/Heteroj...lar_Transistor http://www.ntt.co.jp/news/news06e/0609/060929a.html "InP ICs, which can be operated at over 50 GHz were used in multiplex and demultiplex circuits..." HTH, Paul "Jason Stacy" wrote in message ... I wonder why a two-core CPU with lets say 2 * 1.7 Mhz is theoretically faster than a single core with 3.4 MHz. I am NOT talking about additional features like Pipeling and Hyperthreading but the core fact that the power is split over two cores. Assume the following situation: A NON-THREADED application needs as much CPU power as possible for some computations. On a 3.4 Mhz machine it can occupied almost 99% of the CPU power (remaining 1 % are for system services). When I run the same application on a two core system then it can occupy only ONE of the two cores with 1.7 MHz. Because it is non-threaded it cannot request the other core as well. So it must be slower (given all other side-conditions are equal). Am I wrong? J. |
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