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Core2 Duo E7600, SSSE3 instead of SSE4.1

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Sutaru Tsureku:
I made a bench test with my new (old) Intel Core2 Duo E7600 @ 3.06 GHz / DDR2 800/5-5-5-18 (stock, not OCed).

I had let run two instances of Knabench V1.81r simultaneously - 'one for one CPU-Core' (without CPU-affinity).


AK_v8b_win_SSE41.exe

TaskName: PG0009.wu - 377.734 secs Elapsed - 375.609 secs CPU time
TaskName: PG0395.wu - 383.344 secs Elapsed - 381.188 secs CPU time
TaskName: PG0444.wu - 319.391 secs Elapsed - 317.344 secs CPU time
TaskName: PG1327.wu - 249.844 secs Elapsed - 247.672 secs CPU time

TaskName: PG0009.wu - 379.125 secs Elapsed - 376.953 secs CPU time
TaskName: PG0395.wu - 383.609 secs Elapsed - 381.516 secs CPU time
TaskName: PG0444.wu - 319.828 secs Elapsed - 317.750 secs CPU time
TaskName: PG1327.wu - 250.641 secs Elapsed - 248.547 secs CPU time


AK_v8b_win_SSSE3x.exe

TaskName: PG0009.wu - 369.000 secs Elapsed - 366.844 secs CPU time
TaskName: PG0395.wu - 351.047 secs Elapsed - 348.969 secs CPU time
TaskName: PG0444.wu - 290.594 secs Elapsed - 288.516 secs CPU time
TaskName: PG1327.wu - 249.484 secs Elapsed - 247.391 secs CPU time


TaskName: PG0009.wu - 371.375 secs Elapsed - 369.281 secs CPU time
TaskName: PG0395.wu - 351.109 secs Elapsed - 348.891 secs CPU time
TaskName: PG0444.wu - 290.453 secs Elapsed - 288.438 secs CPU time
TaskName: PG1327.wu - 249.594 secs Elapsed - 247.422 secs CPU time


I thought SSE4.1 is faster (only) on Core2 Duo CPUs?

Or only on the E8xxx series?

Jason G:

--- Quote from: Sutaru Tsureku on 08 Jun 2010, 04:21:22 am ---I thought SSE4.1 is faster (only) on Core2 Duo CPUs?

Or only on the E8xxx series?
--- End quote ---

It's actually dependant on the memory bus contention mostly, and indirectly via cache size.  So as usual no choice is absolute given those CPUs did not exist when those comparisons were made, & these CPUs have a smaller cache than 8xxx series. 

'Usually', since fast Duos have less contention than Quads (dual channel ram on 2 cores instead of 4 cores) the SSE4.1 build is equal or faster with fast RAM, but slower with slow RAM, however the smaller cache changes things again.

To Test: If you slow that RAM down more SSSE3x should be better by a greater margin.  If it is possible to OC that ram, especially run lower latency, then the SSE4.1 build is likely to overtake somewhere around 960MHz @ cl4.

Your system shows a pretty big difference. That difference gets less and swaps places as memory system performance goes up. In some cases that swapping can include Quads that have extreme RAM & lots of cache also.

Jason

Raistmer:
"SSE4.1" could be faster for hosts with relatively fast memory bus. Your host uses 800MHz memory so very likely memory bus saturated enough to give advantage of cache handling used in SSSE3x build. That's memory/cache issues, not SSE level of CPU per se.
IMO SSE4.1 build leaved mostly for peoples who can't understand that bigger!=better sometimes. SSE4.1 will win on some hosts indeed, but not on many IMO and surely not on all who can support SSE4.1 instruction set.

Jason G:
Duplicating your test on E8400 @3.6GHz w/Dual Channel DDR2@960MHz, Win7x64 (Second core loaded with Boinc):

  AK_v8b_win_SSSE3x.exe
TaskName: PG0009.wu -  293.020 secs Elapsed -  290.318 secs CPU time
TaskName: PG0395.wu -  267.220 secs Elapsed -  264.531 secs CPU time
TaskName: PG0444.wu -  210.280 secs Elapsed -  207.793 secs CPU time
TaskName: PG1327.wu - 154.550 secs Elapsed -  152.195 secs CPU time
                                                                      Total CPU 914.837

  AK_v8b_win_SSE41.exe
TaskName: PG0009.wu -  289.011 secs Elapsed - 286.777 secs CPU time
TaskName: PG0395.wu -  263.460 secs Elapsed -  260.880 secs CPU time
TaskName: PG0444.wu -  214.420 secs Elapsed -  211.818 secs CPU time
TaskName: PG1327.wu -  154.311 secs Elapsed -  151.508 secs CPU time
                                                                      Total CPU 910.983 - speedup = 0.42%

Pretty close!  ;) So close it doesn't really matter anymore.  I do plan to upgrade my RAM further in the near future, and so it will probably all change again.

Jason

Raistmer:
with so small differencies one time measured numbers w/o standard deviation just have no sense actually. Times are the same.

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