Currently I develop on an extremely powerful machine: Pentium i7, 32 GB Ram, SSD, 1 Gb 1028-bit graphics card, etc.
What I'm trying to figure out is the proper way to test my applications and web pages simulating a less powerful computer. Is there any way to simulate a slower processor, less ram, slower hard drive, and weaker graphics card? I'm not sure if I missed anything else in terms of what else to simulate...
The only thing I've figured out so far is resolution, but that was as easy as changing my monitor resolution. Though, if there is a way to simulate less resolution without needing to change my actual screen resolution as well, that'd be great.
Download Windows Virtual PC.
And test you application in it. You can customize your configuration, everything like disk storage, ram memory etc.
Good application for application developers to test in different environments.
I suppose you could create a virtual machine on your computer. You could then vary how much RAM & processing power it has access to. You could boot this machine of a USB drive if you wanted to simulate a slower drive.
Related
As the title says I'm looking to approximate the performance of a piece of code on different hardware setups. Are there any tools out there to do this?
I'm looking to run my code and perform measurements by limiting the resources available to the process. I would like to control things such as total memory available as well as cpu usage, but it would be better if I had more granularity. Are there any tools out there that would allow me to emulate different speeds of RAM, rate limit the cpu (to say X gigaflops), slow down disk reads, etc?
I've already been looking at the setrlimit command in linux, but I don't think it will let me emulate things like latency. I considered using VMs to run the code and just tweaking the memory and cpu but I'm not sure its granular enough. I also considered things like hooking some of the syscalls and just spinning for x nanoseconds before allowing a read/write syscall, but it feels kind of clunky. The other issue is that this code primarily runs on Windows, and if possible it would be preferable to do this on Windows.
Just for some background, I'm trying to provide some reasonably accurate estimates of things like runtime and resource utilization on different hardware setups without having to actually buy, assemble, and test said hardware.
Thanks for any help you can provide.
If you wish to get very detailed control of every possible part of a machine, use a software emulated machine such as Bochs. Bochs will emulate, in software, an x86 CPU, hard drive, video card, network card, everything.
In order to do what you want to do you would need to build your own version of Bochs with changes to the emulator to control the speed of the different pieces.
Excuse me for my lack of knowledge but I am really new to the Virtual world and have a few questions.
I work for a small charity who specialise in providing basic IT training. We have recently acquired a few Dell Poweredge 2650 servers and Dell desktops and we wish to offer both XP, Windows 7, Mac and Ubuntu training. I am looking at setting up a Virtual environment so that we can have a standard image for each OS (I currently use image files but it currently takes approximately 25mins to build each machine and multi-boot is not an option as the new machines have 20Gb disks).
The servers are all dual processor and we can purchase more memory(I need to justify the cost)
What are the memory requirements for
the Host?
How many VM's can I run
per server?
Can I run multiple instances of the same VM
Thanks in advance for your knowledge.
Darryn
You might be able to get away with a multi-boot option with those 20 gig disks; each OS will probably take no more than ten gigs for minimal installs, two OSes per machine isn't terrible. (Incidentally, look around for a group like FreeGeek in your area -- larger hard drives ought to be cheap for small sizes like 120-500 gigs.)
That said, virtualization might be just what you need, if you have a handful of pretty powerful machines.
I think between one and two gigabytes of host memory for every guest VM that you want to run would be very useful. At least in my experience, an Ubuntu image I gave 1024 megabytes to ran very quickly, but I didn't press it very far. Running Firefox or OpenOffice inside the VM would probably dictate more memory very quickly. Chrome seemed snappy.
So, if you've got 12 gigabytes of RAM, you might be able to get between four and twenty virtual machines hosted on the machine simultaneously, depending upon what your guests are doing.
As for disk space, if you use QEMU's -snapshot option, you ought to be able to save disk space. Each user could boot the same underlying disk image, but their own modifications would go into the 'snapshot' file. (I have no experience trying to do long-term system maintenance with this option, so it could be that all twenty of your users need to store service pack 2 contents when they upgrade in the future; I'd be scared of trying to modify the shared disk image once you've got snapshots of it running. Perhaps having everyone store 'personal documents' and the like in CIFS shares would make a ton of sense.)
The biggest hurdle will probably be Mac; because the Apple terms of service forbid running OS X on non-Apple hardware, you'll have to have some Apple machines around to run VirtualBox.
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.
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
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...
Create some virtual machines.
You can use VirtualPC or VirtualBox both are free.
I would recommend to start something on the background which eats up all your processor cycles.
A program which finds primenumbers or something similar.
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.
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.
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.
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.
I understand that this question is pretty old, but here are some receipts I personally use (not only for Web development):
BES. I'm getting some weird results while using it.
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.
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.
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 New 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.)
Lately I have been thinking about investing in a worthy USB pen drive (something along the lines of this), and install Operating Systems on Virtual Machines and start developing on them.
What I have in mind is that I want to be able to carry my development boxes, being a Windows Distribution for .Net development and a Linux Distribution for stuff like RoR, Perl and whatnot, so that I would be able to carry them around where need be...be it work, school, different computers at home etc...
I am thinking of doing this also for backup purposes...ie to backup my almost-single VM file to an external hd, instead of doing routinely updates to my normal Windows Box. I am also thinking about maybe even committing the VM boxes under Source Control (is that even feasible?)
So, am I on the right track with this ? Do you suggest that I try to implement this out?
How feasible is it to have your development box on Virtual Machine that runs from a USB Pen-Drive ?
I absolutely agree with where you are heading. I wish to do this myself.
But if you don't already know, it's not just about drive size, believe it or not USB Flash drives can be much slower than your spinning disk drives!
This can be a big problem if you plan to actually run the VMs directly from the USB drive!
I've tried running a 4GB Windows XP VM on a 32GB Corsair Survivor and the VM was virtually unusuable! Also copying my 4GB VM off and back onto the drive was also quite slow - about 10 minutes to copy it onto the drive.
If you have an esata port I'd highly recommend looking at high-speed ESata options like this Kanguru 32GB ESata/USB Flash drive OR this 32GB one by OCZ.
The read and write speeds of these drives are much higher over ESata than other USB drives. And you can still use them as USB if you don't have an ESata port. Though if you don't have an ESata port you can buy PCI to ESata cards online and even ESata ExpressCards for your laptop.
EDIT: A side note, you'll find the USB flash drives use FAT instead of NTFS. You don't want to use NTFS because it makes a lot more reads & writes on the disk and your drive will only have a limited number of reads & writes before it dies. But by using FAT you'll be limited to max 2GB file size which might be a problem with your VM. If this is the case, you can split your VM disks into 2GB chunks. Also make sure you backup your VM daily incase your drive does reach it's maximum number of writes. :)
This article on USB thumbdrives states,
Never run disk-intensive applications
directly against files stored on the
thumb drive.
USB thumbdrives utilize flash memory and these have a maximum number of writes before going bad and corruption occurs. The author of the previously linked article found it to be in the range of 10,000 - 100,000 writes but if you are using a disk intensive application this could be an issue.
So if you do this, have an aggressive backup policy to backup your work. Similarly, if when you run your development suite, if it could write to the local hard drive as a temporary workspace this would be ideal.
Hopefully you are talking about interpreted language projects. I couldn't imagine compiling a C/C++ of any size on a VM, let alone a VM running off of a USB drive.
I do it quite frequently with Xen, but also include a bare metal bootable kernel on the drive. This is particularly useful when working on something from which a live CD will be based.
The bad side is the bloat on the VM image to keep it bootable across many machines .. so where you would normally build a very lean and mean paravirtualized kernel only .. you have to also include one that has everything including the kitchen sink (up to what you want, i.e. do you need Audio, or token ring, etc?)
I usually carry two sticks, one has Xen + a patched Linux 2.6.26, the other has my various guest images which are ready to boot either way. A debootstrapped copy of Debian or Ubuntu makes a great starting point to create the former.
If nothing else, its fun to tinker with. Sorry to be a bit GNU/Linux centric, but that's what I use exclusively :) I started messing around with this when I had to find an odd path to upgrading my distro, which was two years behind the current one. So, I strapped a guest, installed what I wanted and pointed GRUB at the new LV for my root file system. Inside, I just mounted my old /home LV and away I went.
Check out MojoPac:
http://www.mojopac.com/
Hard-core gamers use it to take world of warcraft with them on the go -- it should work fine for your development needs, at least on Windows. Use cygwin with it for your unix-dev needs.
I used to do this, and found that compiling was so deathly slow, it wasn't worth it.
Keep in mind that USB flash drives are extremely slow (maybe 10 to 100 times slower) compared to hard drives at random write performance (writing lots of small files to a partition which already has lots of files).
A typical build process using GNU tools will create lots of small files - a simple configure script creates thousands of small files and deletes them again just to test the environment before you even start compiling. You could be waiting a long time.
We have decided to go with a virtualization solution for a few of our development servers. I have an idea of what the hardware specs would be like if we bought separate physical servers, but I have no idea how to consolidate that information into the specification for a generalized virtual server.
I know intuitively that the specs are not additive - I shouldn't just add up all the RAM requirements from each machine to get the RAM required for the virtual server. I can't really treat them as parallel systems either because no matter how good the virtualization software is, it can't abstract away two servers trying to peg the CPU at the same time.
So my question is - is there a standard method to estimating the hardware requirements for a virtualized system given hardware requirement estimations for the underlying virtual machines? Is there a +C constant for VMWare/MS Virtual Server overhead (and if so, what is C?)?
P.S. I promise to move this over to serverfault once it goes into beta (Promise kept)
Yes add 25% additional resources to manage the VM. So if I need 4 servers that are equal to single core 2 ghz machines with 2 gigs of ram I will need 10 ghz processing power plus 10 gigs of ram. This will allow all systems to redline and still be ok.
In the real world this will never happen though, all your servers will not always be running all the time. You can get a feel for usage by profiling your current servers and determine their exact requirements and then adding an additional 25% in resources.
Check out this software for profiling utilization http://confluence.atlassian.com/display/JIRA/Profiling+Memory+and+CPU+usage+with+YourKit
The requirements are in fact additive. You should add up the memory requirements for each VM, and the disk requirements, and have at least one processor core per VM. Then add on whatever you need for the host system.
VMs can share a CPU, to some extent, if you have really low performance requirements, but they cannot share disk space or memory.
Answers above are far too high, second (1 core per VM) is closer. You can either 1) plan ahead and probably over-purchase 2) add just-in-time. Do you have some reason that you must know well ahead (yearly budget? your chosen host platform doesn't cluster hosts, so you can't add later?)
Unless you have an incredible simple usage profile, it will be hard to predict before and you'll over purchase. The answer above (+25%) would be several times more than you need for an modern server virtualization software (VMware, Zen, etc) that manages resources smartly. It's accurate only for desktop products like VPC. I chose to rough it out on a napkin and profile my first environment (set of machines) on the host. I'm happy.
Examples of things that will confound your estimation
Disk space, Some systems (Lab
Manager) use only the difference in
space from the base template. 10
deployed machines with 10 GB drives
using about 10 GB (template) + 200MB.
Disk space: You'll then find you
don't like the deltas in specific
scenarios.
CPU / Memory: This is dev
shop - so you'll have erratic load.
Smart hosts don't reserve memory and CPU.
CPU / Memory: But then you'll
want to do perf testing, and want to
reserve CPU cycles (not all hosts can
do that)
We all virtualize for different reasons. Many of the guests
in our environment don't have much work. We want them there to see how something behaves with a cluster of 3 servers of type X. Or, we have a bundle of weird client desktops waiting around, being used one at time by a tester. They rarely consume many host resources.
So, if you are using something like that doesn't do delta disks, disk space might be somewhat calculable. If lab manager (delta disk), disk space is really hard to predict.
Memory and processor usage: You'll have to profile or over-purchase heavily. I have many more guest CPUs than host CPUS, and don't have perf problems - but that's because of the choppy usage in our QA environments.