Maximizing performance

[Ticklebur]

If I run 3 clients I get 60fps no problem using default gfx settings, with 5 clients I get 30fps avg with lowest graphics settings. While I'd like to say that WoW scales, it doesn't. running 2x the number of clients doesn't result in 50% of the perf per-client, it results in far worse. At some point a system hits its own limit in terms of CPU, GPU and Memory.

The first bottle-neck is the CPU, CPU-use does in-fact scale. The CPU use of 1 client can be multiplied evenly to determine your max supportable clients (without overheating, you can obviously push beyond the calculated limit at the expense of heat and FPS).

The second bottle-neck is GPU, GPU-use does not scale. I don't blame WoW for this, it's likely driver and or hardware specific. In my case, I had to turn texture filtering down to the lowest setting, so, in my case, I assume the bottle neck is the GPU bus-clock and/or pipelines for texture processing. A particular make of a graphics card usually only has so many pipelines for processing, and can only move data along those pipelines so fast. I don't know the spec of your gfx card, but it would be interesting to know what your FPS are with 5 clients on your machine. Like I said, 3x clients runs like butter on my rig (and probably most rigs which were 'decent' circa 2005/2006) but tack on another two instances and you may find that, while your CPU isn't pegged, WoW may be IO bound against the graphics card, first the bus, then the available pipelines.

Is there anyone who is DX/GPU savvy enough to detail how perf can be monitored for ATI and NV graphics cards? For example, is there any way to determine if/when you are IO bound on the bus of your gfx card, or constrained by the available GPU, etc?

As a side note, my P4 2ghz, 2GB ram and ATI X800 512MB could only 'cleanly' run 1 instance of WoW, the constraint was CPU. Running once instance of WoW eats about 90% cpu. Running additional instances reduced performance for each instance, the most I ran was 4 instances and performance at that point became unbearable. I ultimately bought a dual-core laptop with an NV 8700m, primarily for the CPU boost. Now I run 5 instances at 90-100% CPU, should do well until Cataclysm, at which point I suspect many of us will be upgrading graphics cards and/or RAM to keep up.

So, what your saying is:
If i upgrade my CPU (be it a new CPU, or new pc) i can run more?

Btw, does it matter if i seriously tune my windows so that it's a gamers edition?
Cuz i tried making my own windows version, and i cut the RAM-usage back to about 30MB.

I don't know a lot about registry tuning, but maybe that will increase performance even more.
I hope so, cuz i don't have the money for a new computer.

[Mubox]

So, what your saying is:
If i upgrade my CPU (be it a new CPU, or new pc) i can run more?

Btw, does it matter if i seriously tune my windows so that it's a gamers edition?
Cuz i tried making my own windows version, and i cut the RAM-usage back to about 30MB.

I don't know a lot about registry tuning, but maybe that will increase performance even more.
I hope so, cuz i don't have the money for a new computer.

It's true that WoW is a CPU-intensive game (e.g. uses more CPU than GPU), so usually upgrading a CPU can have a more positive impact than upgrading anything else (GPU, RAM).

However, WoW is also RAM-intensive, since WoW doesn't immediately flush unnecessary data out of memory as you change zones (since it's cheaper to swap the data back into memory than to re-load it from a a compressed MPQ + in-memory re-init.)

To know if a CPU Upgrade would benefit you, simply crack open Task Manager (taskmgr.exe, or CTRL+SHIFT+ESC Hotkey) and switch to the Performance Tab. It should show CPU Utilization. If CPU Use appears at 100% you are "CPU-bound", that is, performance in WoW is negatively impacted due to a lack of CPU. If CPU Use doesn't ever hit 100% then you are not CPU-bound.

On my machine, I can run 4 instances at an average of 90-95% CPU, depending on what is going on. I get 30-40 fps. With 5 clients I become CPU-bound, CPU is constantly at 100% and my fans go into overdrive. I've actually had my box shutdown due to heat 3 times over the last 6 months.

Even if you are CPU bound, it may still take a heavy CPU upgrade to get any real benefit. Such as my case. If 4 clients are at 90% CPU I can extrapolate that each instance is using roughly 23% CPU, thus, I would need an upgrade that reduced the CPU cost of running wow by roughly 5% per instance, or put another way, I would need a CPU upgrade that improved my CPU performance by (5%*5)=25% to provide my 5th instance with the extra CPU it needed to not be CPU-bound. Unfortunately, there is no CPU swap I can perform to become unbound from the CPU in my machine. So, I'm stuck waiting until I can upgrade to a significantly faster system (Probably a quad-core i7, which would probably increase the number of instances I can run significantly.)

I "local-box" 5 instances, and in AV's my FPS can dive down to 6fps. I blame this on a combination of CPU, BUS Clock (MB and Gfx) and GPU performance. With 30+ geared toons surrounding me I simply lack the power overall to handle the load. My point? Even if you can increase CPU, you may find you are still bound to bus clock rates (you can only move data around so fast) and available GPU performance (I have a "lowly" 8700m, 512MB.)

So, it would help to know what you have in terms of hardware, and what your upgrade options are. This is why I was curious if there was any tool out there that would indicate being IO-bound or GPU-bound, because a CPU upgrade may not always solve the problem (it may only be part of the solution.)

My current rig is a single Core2 Duo 2.0Ghz Laptop with a 512MB 8700m and 4GB of Ram, running on Windows7 X64. For the most part, I get decent-enough framerates running 5 instances of WoW to not claw my eyes out. FPS is usually above 20-25fps.

On the subject of Memory usage, I use a multibox app that lets me "trim" memory per-instance of WoW, I trim at 612MB. This trim occurs every 30-60 seconds or so, which allows WoW to "grow" momentarily when it really needs to. This trim ensures that each instance of WoW only ever uses 612MB of physical memory. 612 * 5 = 3060MB, or 2.9GB. This is nearly all my physical memory (as out of 4GB, 1GB is reserved by the host hardware for shadowing video, audio and other hardware-writible portions of memory.) Thus, runnign 5 instances I've consumed almost all my physical memory. I've tried trimming wow down to 256MB of memory, but I wind up seeing "gray texture" glitches in-game. 512 seemed sufficient, but I simply pdid the math and ensured that each instance of WoW got an equal share of ALL my physical RAM.

With memory trimming, I can ensure no one instance of WoW overtakes all of my physical. Without this, I lack the memory to run WoW and experience occasional swap-hell when zoning, running through Orgrimmar, etc. If left unchecked, during my casual play WoW will eat as much as 800MB of memory. On average, with everything tuned down, WoW consumes 400MB of physical and 200MB swap. IMO per instance of WoW you will want 512MB of memory, and also assuming that the total memory of all AddOns is under 32MB, it's possible for a full AddOn suite to each more than 100MB of RAM easy.)

Lastly. Heat management.

Modern CPUs will degrade their own performance internally as they reach a critical tempurature, I believe this is around 77 degrees celcius (I could be wrong.) Once a critical tempurature is hit the Cores will clock at 0, halting the system until the heat dissipates. If heat does not dissipate, a modern system will reboot. Some systems may opt to reboot instead of clocking down to 0. I haven't researched this behavior since the P4 began "stepping" its clock rate due to overheating.

What this means, though, is that poor heat dissipation will negatively impact CPU performance. For example, I smoke, and I ash right next to my laptop. Call it what you will. The problem I had was severe overheating. My fans would run full-blast non-stop and my framerates would decline to <20FPS. Why? Because the ash from my smoking was building up on all of the cooling components (fan, heat-sink fins, etc.)

I went out, bought a can of air (Eckard's Can-of-Air or Duster, 3-5$ depending) and sprayed everything clean. The result? My framerates have improved from <20fps to >30fps, and my fans, well, I don't hear them at all Moral? Check your cooling components, you'd be surprised what a can of air can do, or at least how excessive heat can ultimately degrade performance.

Hope that helps.