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How to 'capture' stuttering

While it's easy enough to display stuttering in real life, showing stuttering in a written article is not as easy. It's very hard to do since most stuttering issues can be very unpredictable both in length and when it occurs - that means they're pretty unrepeatable. So, we ask ourselves, just how can we capture stuttering. Here's what we come up with.

Most random stuttering issues are caused by not having enough memory (barring driver and game bugs). So, we're going to test these games again with both 512 MB and 2 GB MB systems. Games with larger than 512 MB memory footprint should force Windows to swap some memory into the page file - and of course, hard disk accesses. To 'capture' stuttering, we'll focus on the first test run results - where stuttering will most likely occur. We'll compare them to average test results from several 'stutter-free' runs (from the last article) to see whether or not there's a difference. A difference in numbers means more likely the games has stuttering issues. Or more appropriately, we have captured the stuttering. Next, we'll look at the fps progress graph to see when and just how much frame rate drops are causing the lower than average test results. Since we want to see whether or not RAID 0 helps stuttering issues, we'll ran the test again with both systems, but with a RAID 0 array. Of course, we also watch the tests as they are run to see whether or not there's any stuttering. Needless to say, this method really only works well with games that have larger than 512 MB memory footprints.

Thankfully, capturing stuttering caused by level loading, automated saves and quick saving are easier - at least we know when they will occur. It's just a matter of measuring how long. To do that, we measure the time it takes for the game to complete saving files to the hard disk - the shorter the better. There are variances with each saves, so we repeat this process three times and compute an average. Level loads measurement are done pretty much the same way. We also did a quick gameplay session to see whether or not we notice any stuttering during these saves. We know it's far from perfect, but it will have to do for now.

Performance Issues with RAID 0

Using RAID arrays with RAID controllers are not without same caveats. The most relevant here are not just storage performance, but also overall system performance. RAID controllers tend to have higher overheads than ordinary SATA or IDE controllers. That means they take more processor time, so your game might run slower since it gets less processor time. We'll take a look at just how much performance difference are there between using ol' plain, ordinary SATA and SATA RAID 0 arrays.

Performance

Just as before, we have to use a system where performance differences can be easily shown. We reused our test setup from the last article, replacing the single hard drive with an RAID 0 array for RAID 0 testing. A reference clocked GeForce 7800GTX which is system limited with this setup, is again used, with a resolution of 1024 x 768, 32 bit - no AA, AF or any other settings are enabled. This also mean not enabling HDR on Splinter Cell: Chaos Theory and Serious Sam II, no Ultra Settings in Quake 4, or Soft Shadows in F.E.A.R. All other settings are maxed out - full detail.

We'd like to thank both Tagan and Kingston for supplying with the additional power supply and 1 GB memory modules for this article.

Our test setup
AMD Athlon 64 3500+ socket 939
2 x 256 MB Kingston KVR 3-3-3 PC3200 DDR-SDRAM
4 x 1024 MB Kingston KVR 3-3-3 PC3200 DDR-SDRAM
MSI K8N NForce 4 SLI motherboard
ASUS EN7800GTX TOP 256 MB GeForce 7800GTX graphics card
(running at reference clocks - 430/600 MHz)
2 x Maxtor DiamondMaxPlus9 80 GBs Serial ATA 8 MB buffer
ASUS E-616 DVD-ROM
450 watts ATX power supply
Tagan TG530-U15 530 watts ATX/BTX power supply

Windows XP Professional with Service Pack 2 installed
NVIDIA Forceware 81.98 reference driver
NVIDIA NForce 4 6.70 reference driver
Creative SoundBlaster Live! 24 bit 5.12.1.512 driver.
DirectX 9.0c

The results:

Looks like there's no point of using more than 512 MB and / or RAID 0 in Dungeon Siege. As a matter of fact, we're actually running the game slightly slower, most likely because of the RAID controller's overhead. It's not much and hardly noticeable in gameplay, but is is slower. So, what about the stuttering with level loads in this game? Well, the stutter is still noticeable, even with 2 GB RAM and RAID on your system.


Unfortunately, the FRAPS fps counter can't really capture the stutter because it was much too quick (under a second). We have to turn to the in game benchmark tool. According to the log, the minimum fps during the benchmark was 6 fps, most likely the frame rate when the stutter occur. So, it looks like having more memory or RAID 0 won't help at all with this particular stutter.

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