V8 Optimized App

[RottenMutt]

i think i found my problem.  quad cores require G1 stepping NB chips.

[Jason G]

Cool, so the question I guess is will the new replacement board have a G1 stepping Northbridge? [ I haven't yet come across that requirement, but am looking ]

[Gecko_R7]

Noticed your comment regarding latency.

So, on a Q6600 Quad for example, Seti would respond better w/ DDR2-800 @ CL-3 than cranking to higher bandwidth, say DDR2-1200 but having to run CL5?

Is this right?

[PS: As a guesstimate , if 3 cycle latency and 400Mhz (DDR2-800) is 7.5ns , and 5 cycle latency at 600MHz (ddr2-1200) is 8.33ns then a small access will start about 10 % faster with the low latency ddr2 800.

So if I was just doing seti and checking my emails I'd go the ddr2-800 low latency,

Thanks Jason.  Makes good sense.  I'm going to give it a whirl and see how it works.
Regards,
Ian

[Jason G]

Thanks Jason.  Makes good sense.  I'm going to give it a whirl and see how it works.
Regards,
Ian

It'll  be interesting to see  if the theories apply in practice on non-server hardware too.  If low latency's the ticket whatever speed you buy I'll have to improve the ram in my old clunkers 

[Later: came across this while looking for old ddr400 in low latency CAS2... part of advertising for Corsair modules]

Performance computing enthusiasts have recognized for some time that latency settings may, in fact, have a greater impact on overall system performance than the overall memory bus speed. Indeed, the latency settings have become even more critical due to current system architecture. The latest chip sets have demonstrated that performance is greatest when the memory bus runs at an integral multiple of the front side bus of the processor. So, the optimum memory performance is attained when the memory bus is synchronous with the processor, and latency settings are reduced to the lowest values possible.

[Gecko_R7]

Thanks Jason. Makes good sense. I'm going to give it a whirl and see how it works.
Regards,
Ian

It'll be interesting to see if the theories apply in practice on non-server hardware too. If low latency's the ticket whatever speed you buy I'll have to improve the ram in my old clunkers

I'm actually going to tighten-up a pair of Team Xtreem DDR2-1200 and try to run 1:1 at 400Mhz & CL3-3-3-8 1T w/ FSB 400x8 on P5k Dlx.

Key word is "try".

[Jason G]

 A Huh, that idea would seem to match what the corsair blurb is saying.  [ I was adding it to my earlier post as you posted]  Good luck.

[Jason G]

i think i found my problem.  quad cores require G1 stepping NB chips.

This is for the Supermicro X7DA8 motherboard?
Can't find info to support this about the northbridge stepping [which doesn't mean it isn't so].  What I am finding suggests it may be the motherboard revision needs to be 2.0+ and latest bios ? how does that compare with what you have ?

[Jason G]

You are right I think, Here 'tis  at http://ftp.supermicro.com/support/faqs/faq.cfm?faq=6423

Question
I have one of your X7DA8 board that I bought in August 2006. I would like to use quad core CPUs on this machine. I see your website indicates that quad core CPUs are supported on this board. Can I just buy quad core CPU and use it on this board?
Answer
Running this CPU on X7 boards requires G1 stepping of Memory controller on the motherboard. This change was implement in November end after Intel released G1 stepping memory controller. So, all the boards manufactured before November would not support quad core CPU.

[RottenMutt]

well i replaced the board with an X7DA3+ last night.  i do not believe the seti performance has increased.  I did notice in Everest it is now reporting dual channel, but with no improvements in any memory benchmarks.
i did get four more dimms of memory so I can try some benchmarks with all 8 dimms populated.  I will also try the X7DA8 with two dual cores to see if the memory preformance increases.

[Jason G]

Theory based on the Mac Pros,  With 8 sticks You'll get *maybe much* more bandwidth, but higher latency, which you prefer will ultimately be up to you! good luck and enjoy

[Jason G]

Oh one more thing, Some users over on NC forum are reporting that SSE3 builds seem to be quicker than the SSSE3 builds at the moment on a core2 based setup.  Can't verify that myself, or figure how a Cloverdale rig fits into that equation.   Something strange there....

[RottenMutt]

well i replaced the board with an X7DA3+ last night.  i do not believe the seti performance has increased.

I'm starting to forum the opinion that nothing is wrong the the computer/mobo and that the difference between the "Darwin" machines and the the Windows machines are just the app and the Mac app preforms much better on V8's then the optimised apps on windows.

[Gecko_R7]

well i replaced the board with an X7DA3+ last night.  i do not believe the seti performance has increased.

I'm starting to forum the opinion that nothing is wrong the the computer/mobo and that the difference between the "Darwin" machines and the the Windows machines are just the app and the Mac app preforms much better on V8's then the optimised apps on windows.

There is a very substantial performance difference of @ 30% to as much as 50% depending on the AR, if you compare OSX V8 and 2.4V on similar platforms.  Hardware is largely not responsible for this. The aps are really 2 different animals that have different lineages and developer approaches.   

Something else to keep in mind is that for Mac, there are really only three Intel flavors required....Core Duo, Core 2 and Xeon.  Alex still does G4 and G5 PPC ports as well, but this is really legacy support.  For x86, developers have to accommodate MANY different CPU & OS combos and generations of same.  This means some consideration has to be given on what development combos will work on the the widest range of the above.  Also, it takes considerable time and effort to alpha and beta build & test for all these different combos...time that could otherwise be re-invested into trying new things for additional incremental improvement.  The x86 aps also are the result of collaborative work and pieces involving MANY people over the past few years.  People come, and people go.  As Jason (j_groothu) can attest, if a new developer has ideas to add/improve the code base, it takes a little while to understand and figure out how the current code is structured & works before one can start down the path of optimizing for it.  It's rather like an architect trying to contribute to a house built in stages by 10 other architects, each with their own specialty and style.  The OSX ap has essentially had 1 main architect the past couple of years who prior to Mactel conversion, was the only active person building PPC aps.  PPC code development requirements were substantially different than X86 considerations..i.e. compilers, libraries, cpu architecture etc. yet many concepts/elements from this port quite well to current x86 Mactels and in some cases, work much better with Intel's development tools. 

All these things add-up over time and result in the different lineages we have today 
In any case, the current aps for all platforms are the quickest ever and testament to the fantastic efforts and dedication of all our developers, past and present. 

Cheers!

[Jason G]

..
 As Jason (j_groothu) can attest, if a new developer has ideas to add/improve the code base, it takes a little while to understand and figure out how the current code is structured & works before one can start down the path of optimizing for it.  It's rather like an architect trying to contribute to a house built in stages by 10 other architects, each with their own specialty and style. 
..

I certainly can attest to that! Frankenstein's Monster might be another good analogy  , I'm somewhere between figuring out how it's structured and how it works.

For the situation with different Hardware/OS/Compilers I like simple car analogies:
- If you are designing a new turbocharger for a specific vehicle it can be highly 'tweaked' for that car / engine, you have a fixed 'platform' to design for.
- If you want a more generic model then it may still be good, but will have compromises involved in the design, maybe size, shape, maybe bolt patterns, capacity, all additional considerations for turbocharger designer.you have a more loosely defined or even shifting platform.

Jason

[RottenMutt]

Here is my latest RAC Graph, the computer crunches 24/7 except when i'm playing Crysis.

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