We have to use C “for performance reasons” [closed]

Answer 1

Using C for embedded systems has got some very good reasons, of which "performance" is only one of the minor. Embedded is very close to the hardware, you need manual memory adressing to communicate with hardware. All the APIs and SDKs are available for C mostly.

There are only a few platforms that can run a VM for Java or Mono which is partially due to the performance implications but also due to expensive implementation costs.

Answer 2

There are situations where you need real-time performance, especially in embedded systems. You also have severe memory constraints. A language like C gives you greater control over execution time and execution space.

So, depending on what you are doing, C may very well be "better" or more appropriate.

Check out the following articles

• http://theunixgeek.blogspot.com/2008/09/c-vs-python-speed.html

• http://wiki.python.org/moin/PythonSpeed/PerformanceTips (especially see Python is not C section)

• http://scienceblogs.com/goodmath/2006/11/the_c_is_efficient_language_fa.php

Answer 3

"Nothing but C is fast [enough]" is an early optimisation and wrong for all the reasons that early optimisations are wrong. If your system has enough complexity that something other than C is desirable, then there will be parts of the system that must be "fast enough" and parts with lighter constraints. If writing your code, for example, in Python will get the project finished faster, with fewer bugs, then you can follow up with some C or assembly code to speed up the time-critical parts.

Even if it turns out that the entire code must be written in C or assembly to meet the performance requirements, prototyping in a language like Python can have real benefits. You can take your working Python prototype and gradually replace parts with C code until you reach the necessary performance.

So, use the tools that let you get the development work done most correctly and most quickly, then use real data to determine where you need to optimize. It could be that C is the most appropriate tool to start with sometimes, but certainly not always, even in embedded systems.

Answer 4

It's hard to argue against C (or other procedure languages like Pascal, Modula-2, Ada) and assembly for embedded. There is a large history of success with those languages. Generally, you want to remove the risk of the unknown. Trying to use anything other than C or assembly, in my opinion, is an unknown. Having said that, there's nothing wrong with a mixed model where you use one of the Schemes that go to C, or Python or Lua or JavaScript as a scripting language.

What you want is the ability to quickly and easily go to C when you have to.

If you convince the team to go with something that is unproven to them, the project is your cookie. If it crumbles, it'll likely be seen as your fault.

Answer 5

Here are a couple articles that compare C# to C++ :

http://systematicgaming.wordpress.com/2009/01/03/performance-c-vs-c/

http://journal.stuffwithstuff.com/2009/01/03/debunking-c-vs-c-performance/

Not exactly what you asked for as it doesn't have a focus on embedded C programming. But it's interesting nonetheless. The first one demonstrates the performance of C++ and the benefits of using "unsafe" code for processor intensive tasks. The second one somewhat debunks the first one and shows that if you write the C# code a little differently then the performance is almost the same.

So I will say that C or C++ can be the clear winner in terms of performance in many cases. But often times the margin is slim. Whether to use C or not is another topic altogether. In my opinion it really should depend on the task at hand. But in embedded systems you often don't have much of a choice.

Answer 6

This article (by Michael Barr) talks about the use of C, C++, assembler and other languages in embedded systems, and includes a graph showing the relative usage of each.

And here's another article, fittingly entitled, Poor reasons for rejecting C++.