Hyper-Threading and SMP Tweaks

Another topic some people will find interesting is Hyper-Threading. We've seen a 10 to 20% performance increase with dual core processors, but HyperThreading is often regarded as a "poor man's SMP". We took the Pentium 4 641 chip and ran test both with and without HyperThreading. Here are the results:

Pentium 4 631 Hyper-Threading
HT Off HT On % Improvement
Oblivion Gate
Min 18 17 -5.56%
Avg 25.1 28.4 13.15%
Max 30 35 16.67%
In Town
Min 16 18 12.50%
Avg 29.1 31.2 7.22%
Max 45 48 6.67%
In Dungeon
Min 22 23 4.55%
Avg 44.9 48.6 8.24%
Max 119 130 9.24%

We were surprised to find that HyperThreading actually brought some pretty substantial performance improvements. The outdoor environment gets the biggest improvement, increasing average frame rates by 13%, but even the town and dungeon tests show a 7-8% increase. Certainly, this is not the difference between playable and unplayable frame rates, but even a small increase is nice to get.

So far, we've been looking at Oblivion performance without performing any special tweaks. While there are certainly many other tweaks that we could make to try to improve performance, we wanted to focus on changes that wouldn't affect the graphics quality but might still improve performance. We turn to TweakGuides.com and used their SMP-enhancing performance tweaks. For this test, we used an Athlon X2 4400+, once again with and without the tweaks enabled.

Athlon X2 4400+ SMP Tweaks
Tweaks Off Tweaks On % Improvement
Oblivion Gate
Min 32 34 6.25%
Avg 44.1 45.7 3.63%
Max 53 55 3.77%
In Town
Min 28 30 7.14%
Avg 48.5 48.9 0.82%
Max 75 74 -1.33%
In Dungeon
Min 36 37 2.78%
Avg 74 74.1 0.14%
Max 178 180 1.12%

As with HyperThreading, the SMP performance tweaks bring slight improvements in performance. However, none of the improvements are higher than 5%, which is roughly the margin of error for our benchmarks. The outdoor benchmark does see the largest increases, however, so some people might find these tweaks to be useful. Unfortunately, we also noticed some graphical glitches with all of the SMP tweaks enabled, so we can't honestly recommend using these tweaks for the small increase in performance. Your mileage may vary, so feel free to try them out; if you need more performance, though, you're better off looking at some of the other modifications you can make.

GPU Performance vs. CPU Clock Speed Final Words
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  • goku - Saturday, April 29, 2006 - link

    It' really ticks me off that oblivion couldn't incorporate support for the new ageia physics processor. It would have been nice to see all those calculations being offloaded onto the PPU instead so that the CPU wouldn't have such an effect on performance.
  • DigitalFreak - Saturday, April 29, 2006 - link

    Since they are using the Havock physics engine, it was never going to happen.
  • DigitalFreak - Saturday, April 29, 2006 - link

    Oops, Havok
  • Madellga - Saturday, April 29, 2006 - link

    I don't think that was supposed to happen, but when I clicked on the link under the tittle:

    SMP - enhacing performance , it goes to http://www.anandtech.com/printarticle.aspx?i=2747">http://www.anandtech.com/printarticle.aspx?i=2747 , which is the same Oblivion CPU article we are reading.

    I think the idea is to take us to the guide you are using, isn't it?

    //s
  • kristof007 - Saturday, April 29, 2006 - link

    Same here. Please fix it Anand when you get a chance.
  • JarredWalton - Saturday, April 29, 2006 - link

    Done. That page was my doing - Anand ran the tests, I wrote page 5. I forgot to paste in the link. (Actually, I ran into some issues with undo/redo and apparently lost the link in the process. I had to rewrite two paragraphs at the time.)

    Jarred Walton
    Hardware Editor
    AnandTech.com
  • shortylickens - Friday, April 28, 2006 - link

    This makes me feel pretty good. I went out of my way to get the cheapest Socket 939 CPU I could find.
    Now that I've had the system for a while, I feel OK about doing one big CPU upgrade and I can actually see a performance boost.
  • bloc - Friday, April 28, 2006 - link

    The sempron line is amd's answer to intels celeron line.

    Might it be possible to see the benches for the Sempron S754 as they're budget cpu's with huge overclocks?
  • kmmatney - Saturday, April 29, 2006 - link

    A Sempron 2800+ overclocked to 2.4 GHz performs about the same as an Athlon 64 3700+ clocked at 2.2 GHz. So for a rough estimate, lower the Athlon64 speed by 10% to get the speed of a Sempron.

    My Sempron overclock at 2.45 Ghz was 100% stable for all games and applications I'd ever used until Oblivion. With Oblivion, the game was crashing until a lowered the spu speed to 2.35 GHz.
  • JarredWalton - Saturday, April 29, 2006 - link

    Part of the problem is that there's only one SLI motherboard for socket 754, and honestly I think that's more of a novelty product than something truly useful. Anyone spending the money on multiple GPUs is better off buying a faster processor as well.

    Anyway, looking at how cache seems to affect performance of the other chips, I would guess that a Sempron 128K/256K would be equivalent to an Athlon 64 512K running 200 to 400 MHz slower. (i.e., Athlon 64 2.0 GHz -- 3200+ -- would probably be about equal to a Sempron 2.3-2.4 GHz.) Single channel memory plus a reduction in cache size should cause a moderate performance hit, clock for clock.

    Of course, none of that means that Sempron chips aren't worth considering, especially with overclocking. Assuming you're not running super high end graphics configurations, though, you can probably reached the point where you're GPU limited to the same performance, whether you have an Athlon X2 or a Sempron.

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