View Full Version : Dual-Core Technology

03-21-2005, 09:19 AM
In conclusion, the activation of HT results in a performance increase if we only use one CPU, but results in a performance decrease as soon as HT is used on a dual CPU configuration.

the behaviour of muti-threaded applications will have to be carefully studied, regarding the problems of Windows XP scheduler to manage four logical CPUs with efficiency.

Win XP and Dual Core HT on : Bug? (http://www.x86-secret.com/?option=newsd&nid=849)

Power5 uses what it knows about the facilities needed by each RISC instruction to, in essence, power down portions of the chip that arenÕt needed at that moment. This potentially puts a new spin on PowerÕs infamous power and heat problems. It certainly seems simpler than OS-driven power management schemes. POWER5 Reviewed (http://www.infoworld.com/article/04/12/10/50FEpower5_2.html)

Binary compatibility
As previously mentioned, code compiled on POWER4 hardware has a very high probability of running unchanged on POWER5 hardware. That is the technical view from the standpoint of the hardware instruction sets. But it is really the supported levels of gcc, libc, middleware, Java, and distributions themselves that ultimately determine binary compatibility for applications between hardware versions. What's New in POWER5 (http://www-128.ibm.com/developerworks/eserver/articles/es-LinuxonPwrovrw.html)

While I can't wait for Tiger, anything that was built using an older compiler may mean trouble; many drivers and applications will need to be updated; some things may not run as well on dual-core/dual-cpu as they did previously I assume, also.

The Quest for More Processing Power,
Part Two: "Multi-core and multi-threaded gaming"
Dual cores are expensive to manufacture. Yields (the number of working chips on one wafer) are roughly proportional to size. Larger, dual core chips will always have lower yields than smaller, single core chips on the same process technology. But that is only a small problem. A bigger and more obvious problem is that you have only half the number per wafer (even slightly less). So, dual cores (such as Pressler) cost at least twice as much to manufacture compared to a single core chip - most likely more (such as Yonah, Pentium-D).

Dual and multi-cores might not increase the thermal density (dissipated power per mm?), but they do increase the total power. Granted, from the viewpoint of a heat sink designer, it is not much harder to cool a 112 mm? Prescott chip that dissipates +/- 90 Watt than a theoretical 206 mm? Pentium-D with 180 Watt. However, making sure that those 180 Watts do not cook all the components inside your computer is almost an impossible task for the system designer who wants to design a relatively silent PC. The result is that multi-core CPUs will run at lower clockspeeds than their single core counterparts. The Pentium-D, the dual core Prescott, is limited to 130 Watt and 3.2 GHz, while the current Prescott dissipates up to 115 Watt and runs at 3.8 GHz.

Bandwidth and Latency:
And last, but not least, dual core CPUs need more bandwidth than a single core to make a difference and increase the "CPU perceived" latency. Cache coherency and getting access to the same memory bus all increase the total latency that the CPU sees and thus, lowers performance.
Much more to read here: Anandtech (http://www.anandtech.com/cpuchipsets/showdoc.aspx?i=2377) Get out those 15K Cheetahs!
Multitasking scenarios might be another way to use the power of dual and multi-cores.

However, many of the CPU heavy applications that desktop and workstation users like to run in the background - archiving, encoding - also operate on the hard disk. And despite the merits of NCQ (Native Command Queuing), high rotation speeds, and lower seek times, disk heavy tasks and especially multithreaded ones can bring a whole system to a crawl when there is too much hard disk activity.

AMD will start at 2.4GHz with its dual core chips... during the second half of this year AMD will introduce a number of dual core Opterons

IBM dual-core X3 Xeon Active PCI-X up to 266MHz

PCI Express boards are hard to build

AMD holds off on DDR-2 support

Freescale shows off dual core Power PC chip
By INQUIRER staff: Wednesday 29 September 2004, 09:55

THE FIRM spun out of Motorola to sell semiconductors said it has started showing off a dual core processor based on the E600 architecture.

The not very excitingly named MPC8641D has two E600 Power PC cores, clocking over 1.5GHz, and including two 1MB level two caches. The processor uses a high bandwidth integrated MPX bus which scales to 667MHz, and includes an integrated dual memory controller for both DDR and DDR-2 memories.

AMD's Dual Core 90nm Opteron Demonstration Dissected (http://www.amdzone.com/modules.php?op=modload&name=Sections&file=index&req=printpage&artid=56)
photo: Dual Core 90nm Opteron First Glimpse (http://www.amdzone.com/modules.php?op=modload&name=Sections&file=index&req=printpage&artid=55)
AMD's Dual-Core Plans for 2005-6 (http://www.pcper.com/article.php?aid=122)
Intel's Extreme dual-core chip to cost $999 (http://www.geek.com/news/geeknews/2005Mar/bch20050318029664.htm)
Intel 840 Pentium X (http://www.theinquirer.net/?article=21929)

03-28-2005, 07:04 AM
Want an idea of what to expect from IBM/Apple 970MP...

AMDboard (http://www.amdboard.com/amdroadmap.html)has posted an interesting roadmap detailing AMD's Opteron plans for the coming year.

The roadmap schedules dual-core Opteron 200- and 800-series chips at 1.8, 2.0, and 2.2GHz for the second quarter of this year, with 100-series equivalents coming in the following quarter.

Dual-core Opterons aren't scheduled to hit 2.4GHz until the first quarter of 2006, although single-core Opterons are show at 2.6 and 2.8GHz in the third and fourth quarters of 2005, respectively.

It's interesting to note that dual-core chips will also be available to the low power crowd.

According to the roadmap, AMD has plans to release dual-core HE Opterons at 1.6, 1.8, and 2.0GHz, and a dual-core EE Opteron at 1.6GHz. Opteron HE processors carry a TDP of 55W, while EE chips are rated for a scant 30W.