Do not be confused my friend.
aaronspink said:
Oh quit being a tard. You're comparing the die area for a single SPU to the whole of Xenos. If you want to thats fine, but a single SPU has 0, NONE, NADA, ZERO, NOTHING in the performance department. So if you really really want to do that comparison, sure we can do it.
Once again you confuse yourself my friend and you forgot origin of the comparison. It is you who said Xenos is better coprocessor for assistance of PPE in tasks PPE is not good for because you said Xenos is more specialized and therefore superior than SPE for such tasks.
If you meant certain parts of Xenos only, you should be more specific. Also, picking only parts of Xenos for your design means you do not really like Xenos for such use but rather prefer new kind of chip using some parts of Xenos but leaving out other parts no?
Also, you are incorrect that single SPE has no performance. Single SPE has 25.6 Gflops performance when used as companion of PPE. It is a individual processor but many can be added to PPE as with STI CELL which has 8 SPE added to 1 PPE.
So you're including the ring, the memory controllers, the PPE, the cache and cache controllers right?
PPE is not included in comparison because the statement of yours is that Xenos is better companion processor to PPE, therefore question is not size or performance of PPE, but rather companion processor, such as SPE or as you proposed Xenos. Therefore only characteristics of companion processor(s) is relevent.
EIB, which is bus connecting SPE and PPE, also not included because if we include that then we must also include any data bus connecting PPE to Xenos in your proposed architecture. Maybe you would like to propose architecture of such bus for your proposed design to connect PPE and (very altered) Xenos if for some purpose you want to include bus characteristics in comparison.
SPE has no cache as such my friend or any cache controller, but it has LS which is not really cache and own DMA unit so all SPE components are included in the comparison. In case you are not aware 2/3 of SPE is just SRAM yet I included it in comparison.
So now you understand that what is relevent to comparison is not characterisitcs of PPE, since your proposal also has PPE, not bus, since your proposal also has bus, but only the companion processor(s) and all components without which it is not what it is..
But since you like to make a comparison of entire CELL to just Xenos chip then you must either add to Xenos or subtract from CELL all transistors and die area of PPE (including PPE cache). I do not know specific transistor count of PPE, but it is approximately 16-17% of die area.
CELL (not including PPE but including eib, memory controller, flexi/o interface, 7 live SPEs + 1 "dead" SPE, etc)
179.2Gflops (from 7 active SPEs)
from 185 Sq. mm = .97 Gflops/sq. mm
As you can see, even after adding all other components of entire CELL including bus and extra "dead" SPE, Xenos is not superior. Activate 8th SPE and Xenos is suddenly 15% inferior.
CELL with 8 active SPEs:
204.8Gflops
from 185 Sq. mm = 1.1 Gflops/sq. mm
So you can see the Xenos, what you call "specialized", is under no circumstances is better than SPE, what you call not specialized. In fact it is inferior so SPE is superior choice as companion to PPE.
Also unlike, as you say, specialized nature of Xenos, SPE is more capable of other tasks as well.
But to return to focus of comparison you originally proposed of Xenos as superior to SPE for companion purpose, here is comparison of STI choice (SPE) of companion processor for PPE with your choice (Xenos):
SPE (single vector processor):
25.6 Gflops ...
from 14.5 Sq. mm = 1.77 Gflops/Sq. mm
from 21m transistors = 1.22 Gflops/million transistors
Xenos (as vector processor, no edram):
192 Gflops ...
from ~200 (?) Sq. mm = .96 Gflops/Sq. mm
from 232m transistors = .83 Gflops/million transistors
So you see my friend Xenos is not effective as companion to PPE.
Get a bloody clue or stay out of the conversation.
There is nothing to be gained from rudeness my friend. Let us maintain civilized discourse no?
