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I have a file encryption program. When the program is encrypting files, it doesn't exceed 25% CPU usage, hence it is slow.

How can I make the OS assign to it more CPU load? (Such as WinRAR, when it compresses files, it reaches 100% from CPU load).

[Edit]: As my cores are 4, it doesn't use more than one core. How can I make it use the rest of cores?

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    If it's not using all the CPU then it is I/O bound, i.e. it's spending time opening/saving the files EDIT: or is not using all CPU cores. You could increase performance by doing multiple encryptions in parallel and loading files while encrypting. – George Duckett Jul 06 '11 at 14:32
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    25% is a fishy CPU number; do you have a quad-core machine? – dlev Jul 06 '11 at 14:33
  • I have only one file encryption per time, could the FileStream's IO slow the process? I have intel i5 CPU –  Jul 06 '11 at 14:34
  • As I am using C#'s streams to IO, it is very related to C#. –  Jul 06 '11 at 14:42
  • @Mr.DDD: Did you try using PFX? Here is an [example](http://stackoverflow.com/questions/5347801/parallel-extensions/5348210#5348210). See my answer. – KMån Jul 06 '11 at 18:54

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Unless you are otherwise throttling the application it will use as much CPU as the OS allows it to - which should be up to 100% by default. I would guess that some other resource is the bottleneck.

Are you streaming the data to encrypt from a remote location? From a disk that is for some reason quite slow?

Yuck
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  • Do you mean I should load the file first to RAM to get speed? But there is a problem, some files are too large for the RAM (Gigabytes) –  Jul 06 '11 at 14:49
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    Buffering is good for improving the performance of accessing remote resources. It's probably not (on its own) going to net you much of a performance benefit related to CPU usage. After reading some of the other answers here I'm leaning toward the notion that a single-threaded app is not benefiting from your multi-core CPU. You might try running the buffering operation on a new thread and doing your encryption in another... – Yuck Jul 06 '11 at 14:55
  • I want to learn more on threading. Is there any good resources? –  Jul 06 '11 at 15:00
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If your tool is single threaded program, then it only consumes one core! And the performance will reach 100% on that core in case your program only do a for loop or other kind of loop. If the tool must do I/O then it never has maximum performance. And 25% you see is per all cpu cores. As I remember there some posts show you how to display the percentage of consumption on each cpu core!

longbkit
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Sometimes people think a high CPU percent means an efficient program. If that were so, an infinite loop would be the most efficient of all.

When you have a program that basically processes files off a mechanical hard drive, ideally it should be IO bound, because reading the file simply has to be done. i.e. The CPU part should be efficient enough that it takes a low percent of time compared to moving the file off disk. Anything you can do to reduce CPU time will reduce the CPU percent, because I/O takes a larger percentage of the total, and vice-versa. If you can go back-and-forth between the two, reducing first CPU (program tuning), then I/O (ex. solid-state drive), you can make it really fly.

Then, if the CPU part is still taking longer than you would like, by all means, farm it out over multiple cores.

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Mike Dunlavey
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Just in case, if you are using v4.0, rather than assigning more CPU load, try using Parallel Framework(PFX). It is optimized for multi core processors..

Parallel.Invoke(() => DoCompress());

Also, Threading in C# is the best threading related resource in the universe.

KMån
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This has nothing to do with the processor and assigning resources: the tool you use is simply not designed to use all (I guess) 4 cores of the cpu.

MADMap
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