dez#80What type of calculations the PS3 client is capable of running?
The PS3 right now runs what are called implicit solvation calculations, including some simple ones (sigmodal dependent dielectric) and some more sophisticated ones (AGBNP, a type of Generalized Born method from Prof. Ron Levy's group at Rutgers). In this respect, the PS3 client is much like our GPU client. However, the PS3 client is more flexible, in that it can also run explicit solvent calculations as well, although not at the same speed increase relative to PC's. We are working to increase the speed of explicit solvent on the PS3 and would then run these calculations on the PS3 as well. In a nutshell, the PS3 takes the middle ground between GPU's (extreme speed, but at limited types of WU's) and CPU's (less speed, but more flexibility in types of WU's).
Tehát, a PS3 valahol közép uton van egy hétköznapi PC (ill. annak CPU-ja: relatíve lassú, de rugalmas), és egy GPU (nagyon gyors, de csak egyszerűbb feladatokkal bírkózik meg) között. Ezért a PS3 egyszerűbb, közepes, és pár bonyolultabb feladattal is megbírkózik.
It seems that the PS3 is more than 10X powerful as an average PC. Why doesn't it get 10X PPD as well?
We balance the points based on both speed and the flexibility of the client. The GPU client is still the fastest, but it is the least flexible and can only run a very, very limited set of WU's. Thus, its points are not linearly proportional to the speed increase. The PS3 takes the middle ground between GPU's (extreme speed, but at limited types of WU's) and CPU's (less speed, but more flexibility in types of WU's). We have picked the PS3 as the natural benchmark machine for PS3 calculations and set its points per day to 900 to reflect this middle ground between speed (faster than CPU, but slower than GPU) and flexibility (more flexible than GPU, less than CPU).
Számítási teljesítményben 10x gyorsabb a PS3, mint egy átlag PC (CPU), de mivel a legbonyolultabb feladatokat nem ennyivel gyorsabban hajtja végre, a relatív pontszáma nem 10x-es.
How are the FLOPS calculated?
People often use the number of Floating point operations per second (FLOPS) as a metric for the speed of a computer. One question that arises is how to compare machines with radically different architectures. In particular, what requires only a few operations (or even just a single operation) on one machine could require many operations on another. Classic examples are evaluations of functions like the exp(x) or sin(x). One GPU and Cell hardware, functions like this can often be calculated very quickly, say in one cycle, while this is often counted as 10-20 operations for other machines.
We take a conservative approach to FLOP calculation, rendering quantities such as exp(x) or sqrt(x) as a single FLOP, if the hardware supports it. This can significantly underestimate the FLOP count (as others would count an exp(x) as 10 or 20 FLOPS, for example). Others take a much less conservative approach and we are considering giving two counts, adding a more traditional (less conservative) count as well.
Külön gyorsítja a PS3-at (és a GPU-t), hogy bizonyos műveletek 1 ciklusosak, miközben egy CPU-nak 10-20 ciklus kell hozzájuk.
Tehát, egy-egy WU, Work Unit nagysága eltérő, de a feladat típusát illetően néhány fajta létezik. Bizonyos feladatokat 10x gyorsabban hajt végre, bonyolultabbakat nem ennyivel gyorsabban.