How To Simulate Lower CPU Processor Machines For Browser Testing

Question

We have some users which are using lower-CPU powered machines and they're encountering slow response times using our web application. Is there any way for me to do testing so that I can simulate lower CPU rates?

For example, I have 2.3 Ghz computing power, can I lower it to 1.6 Ghz or lower so that I may be able to test it?

BTW, our customers are using Windows. I have to simulate low computing power on Internet Explorer as browser.

Hick

Answer 1

Most new CPUs multiplier can easily be lowered (Intel: Speedstep, AMD: PowerNow!). This is used to save power. With RMclock you can manually adjust your multiplier and thus lower your frequency and make your pc slower. I use this tool myself so I can tell you that it works.

http://cpu.rightmark.org/products/rmclock.shtml

Brian

Answer 2

The virtual machine Bochs(pronounced boxes) allows you to set a instructions per second directive. It's probably the slowest emulator out there as it is though...

Bolton

Answer 3

Create some virtual machines.

You can use VirtualPC or VirtualBox both are free.

Irade

Can these virtual pc's be CPU throttled? VMware doesn't seem to be able to do it – Merganser

Not even VirtualBox according to this post: mail-archive.com/[email protected]/msg06567.html. It can be done with VMWare ESX. – Ferdelance

I was checking vmware fusion, which can not do it. – Merganser

Even Virtual PC cannot do that according to this 2007 blog post: blogs.msdn.com/virtual_pc_guy/archive/2007/05/14/… – Ferdelance

daniel: haha that makes this answer a high upvoted answer for something which is incorrect. – Merganser

I think this is very difficult to simulate, even with server virtualization software likve VMWare ESX, Hyper-V and Virtual Server. Remember that virtualization is focused on the opposite: Making direct use of CPU resources as much as possible. – Ferdelance

same here, don't know how to actually set the virtual machiens to only use this much cpu. afaik, you can set th e number of cpu's that the virtual machine would use. – Hick

I believe QEMU can do it, since it can simulate arbitrary architectures. I think you could just specify the same chip your customers are using. When running in this mode, you can't use KVM, however, which potentially will make it slower than you want. – Conciliatory

Answer 4

I would recommend to start something on the background which eats up all your processor cycles.

A program which finds primenumbers or something similar.

Merganser

Or do something really processor intensive like starting outlook ;^) – Merganser

"I'm not playing games, I'm testing!" pew pew pew – Moneybags

That's a horrible suggestion if we think about the environmental impact. – Familiarity

Answer 5

Another slight option in addition to those above is to boot windows in a lower resource config. Go to the start menu,, select run and type MSCONFIG. You can go to the boot tab, click on advanced options and limit the memory and number of of processsors. It's not as robust as the above, but it does give you another option.

Thain

Answer 6

Lowering the CPU clock doesn't always give expected results.

Newer CPUs feature architecture improvements which make them more efficient on an equvialent clock basis than older chips. Incidentally, because of this virtual machines are a bad way of testing performance for "older" tech as well.

Your best bet is to simply buy a couple of older machines. Using similar RAM (types and amounts), processor, motherboard chipsets, hard drives, and video cards. All of which feed into the total performance of the machine itself.

I bring the other components up because changing just one of them can have an impact on even browser performance. A prime example is memory. If your clients are constrained to something like 512MB of RAM, the machines could be performing a lot of hard drive access for VM swaps, even for just running the browser. In this situation downgrading the clock speed on your processor while still retaining your 2GB (assuming) of RAM would still not perform anywhere near the same even if everything else was equal.

Ephebe

Answer 7

Isak Savo'sanswer works, but can be a bit finicky, as the modern tpl is going to try and limit cpu load as much as possible. When I tested it out, It was hard (though possible with some testing) to consistently get the types of cpu usages I wanted.

Then I remembered, http://www.cpukiller.com/, which does this already. Highly recommended. As an aside, I found this util from playing old 90s games on modern machines, back when frame rate was pegged to cpu clock time, making playing them on modern computers way too fast. Great utility.

Muezzin

Answer 8

Another big difference between high-performance and low-performance CPUs is the number of cores available. This can realistically differ by a factor of 4, way more than the difference in clock frequency you're likely to encounter.

You can solve this by setting the thread affinity. Even IE6 will use 13 threads just to show google.com. That means it will benefit from a multi-core CPU. But if you set the thread affinity to one core only, all 13 IE threads will have to share that one core.

Increate

Answer 9

I understand that this question is pretty old, but here are some receipts I personally use (not only for Web development):

1. BES. I'm getting some weird results while using it.

2. Go to Control Panel\All Control Panel Items\Power Options\Edit Plan Settings\Change Advanced Power Settings, then go to the "Processor" section and set it's maximum state to 5% (or something else). It works only if your processor supports dynamic multiplier change and ACPI driver is installed correctly.

3. Run Task Manager and set processor affinity to a single core (or whatever number of cores you want) for your browser's (or any other's) process. Not a best practice for browsers, because JavaScript implementations are usually single-threaded, but, as far as I see, modern browsers actually DO use multiple cores.

Samarskite

Answer 10

There are a few different methods to accomplish this.

If you're using VirtualBox, go into the Settings for the VM you want to slow the CPU speed for. Go to System > Processor, then set the Execution Cap. The percentage controls how slow it will go: lower values are slower relative to the regular speed. In practice, I've noticed the results to be choppy, although it does technically work.

It is also possible to set the CPU speed for the whole system. In the Windows 10 Settings app, go to System > Power & Sleep. Then click Additional Power Settings on the right hand side. Go to Change Plan Settings for the currently selected plan, then click Change Advanced Power Plan Settings. Scroll down to Processor Power Management and set the Maximum Processor State. Again, this is a percentage. Although this does work, I find that in practice, it doesn't have a big impact even when the percentage is set very low.

If you're dealing with a videogame that uses DirectX or OpenGL and doesn't have a framerate cap, another common method is to force Vsync on in your graphics driver settings. This will usually slow the rendering to about 60 FPS which may be enough to play at a reasonable rate. However, it will only work for applications using 3D hardware rendering specifically.

Finally: if you'd rather not use a VM, and don't want to change a system global setting, but would rather simulate an old CPU for one specific process only, then I have my own program to do that called Old CPU Simulator.

The main brain of the operation is a command line tool written in C++, but there is also a GUI wrapper written in C#. The GUI requires .NET Framework 4.0. The default settings should be fine in most cases - just select the CPU you'd like to simulate under Target Rate, then hit Open and browse for the program you'd like to run.

https://github.com/tomysshadow/OldCPUSimulator (click the Releases tab on the right for binaries.)

The concept is to suspend and resume the process at a precise rate, and because it happens so quickly the process will appear to just be running slowly. For example, by suspending a process for 3 milliseconds, then resuming it for 1 millisecond, it will appear to be running at 25% speed. By controlling the ratio of time suspended vs. time resumed, it is possible to simulate different speeds. This is completely API agnostic (it doesn't hook DirectX, OpenGL, etc. it'll work with a command line program if you want.)

Old CPU Simulator does not ask for a percentage, but rather, the clock speed to simulate (which it calls the Target Rate.) It then automatically determines, based on your CPU's real clock speed, the percentage to use. Although clock speed is not the only factor that has improved computer performance over time (there are also SSDs, faster GPUs, more RAM, multithreaded performance, etc.) it's a good enough approximation to get fairly consistent results across machines given the same Target Rate. It also supports other options that may help with consistency, such as setting the process affinity to one.

It implements three different methods of suspending and resuming a process and will use the best available: NtSuspendProcess, NtQuerySystemInformation, or Toolhelp Snapshots. It also uses timeBeginPeriod and timeEndPeriod to achieve high precision timing without busy looping. Note that this is not an emulator; the binary still runs natively. If you like, you can view the source to see how it's implemented - it's not a large project. On my machine, Old CPU Simulator uses less than 1% CPU and less than 1 MB of memory, so the program itself is quite efficient (unlike running intensive programs to intentionally slow the CPU.)

Nygaard