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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  • RyanHirst - Sunday, April 30, 2006 - link

    hehe it's ok. Just chompin' at the bit curious, that's all. If anyone on eBay wanted the collectible books I no longer need, I'd have turned them into a magic pair of 275s and I'd know. Alas. Pantone 072 Blue.
  • bob661 - Saturday, April 29, 2006 - link

    I guess this round of testing only applies to ATI video cards. I guess us Nvidia owners are left to guess how CPU performance affects GPU performance. Oh well. :(
  • PrinceGaz - Sunday, April 30, 2006 - link

    Just refer to part 1 of the Oblivion article and find out where your nVidia card of choice lies in relation to the four ATI cards tested this time and it is easy to see how it will perform with various CPUs.
  • Bladen - Saturday, April 29, 2006 - link

    My guess as to why CPUs help so much in towns is because the Radiant AI takes a fair amount of power.
  • BitByBit - Saturday, April 29, 2006 - link

    I don't know why, but the benchmark graphs didn't appear at all in that review, nor did they in the previous Oblivion review; I get nothing where the graphs should be.
    Has anyone else had this problem?
  • blackbrrd - Saturday, April 29, 2006 - link

    If you have turned off refering you won't see any images.
  • JarredWalton - Saturday, April 29, 2006 - link

    Someone else had a problem with Norton Internet Security blocking images for some reason.
  • Madellga - Monday, May 1, 2006 - link

    That was me. Turn off privacy control.
  • RyanHirst - Saturday, April 29, 2006 - link

    This article still left me with the nagging question about multithread performance. The oblivion team made reference to th game being heavily optimized for multithread performance because they knew from the beginning they'd be writing it simultaneously for the XBox360.
    So the debate about the potential of multithread code in games has been going on for awhile, and here we have the perfect game test, and we happen to know AnandTech had a couple of four-way servers in the shop over the last few weeks.... but the CPU guide leaves that question unanswered.
    If it's not unreasonable to heap $1200 in graphics hardware onto a M/B for a game that is GPU bound only half of the time (outdoors), is it too much to ask that a $1200 pair of Opteron 275's be tested to see how multithread the first advertised multithread game really is? Is it not possible that the game can offload a large number of threads to extra cores?
    If we can talk about throwing over $1K at a game, isn't anyone the least bit curious how a 4-core opteron rig with 4 gigs of RAM in NUMA might handle this game?
  • JarredWalton - Saturday, April 29, 2006 - link

    P4 EE 955 runs up to four threads, and it doesn't seem to get any help from the extra capability. It could be that further INI tweaks would allow Oblivion to run better on multi-core (more than 2 core) systems, but if going from 1 to 2 cores gives 10 to 20% more performance, there's a very good chance that moving from 2 to 4 cores wouldn't give more than another 5%. Ideally, a CPU-limited game should be able to get as much as 50% or more performance from multi-threading, but rarely can we realize the ideal case.

    Also, FYI, the servers are at a completely different location than the GPUs for this testing. They also don't support dual X1900 cards in CrossFire - they might not even have X16 PCIe slots, let alone two of them. Servers are, quite simply, not interested in improving gaming performance. There are a few out there targeting the 3D graphics workstation that might support SLI, but not CrossFire. Multi-core will really only become important when we have multi-core CPUs. The desktop/home PC market isn't interested in multiple socket motherboards (other than a few extreme enthusiasts).

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