152
votes
Accepted
When do function call costs still matter in modern compilers?
It depends on your domain.
If you are writing code for low-power microcontroller, then method call cost might be significant. But if you are creating normal website or application, then method call ...
- 37.4k
146
votes
Accepted
When to optimize for memory vs performance speed for a method?
Instead of speculating about what may or may not happen, let's just look, shall we? I'll have to use C++ since I don't have a C# compiler handy (though see the C# example from VisualMelon), but I'm ...
- 1,569
131
votes
Accepted
Is it bad practice to write code that relies on compiler optimizations?
Employ the least astonishment principle.
Is it you and only ever you who is going to use this code, and are you sure the same you in 3 years is not going to be surprised by what you do?
Then go ...
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108
votes
Accepted
Can we make general statements about the performance of interpreted code vs compiled code?
No.
In general, the performance of a language implementation is primarily dependent on the amount of money, resources, manpower, research, engineering, and development spent on it.
And specifically, ...
- 104k
82
votes
Is it bad practice to write code that relies on compiler optimizations?
For this particular case, definitely just return by value.
RVO and NRVO are well-known and robust optimizations that really ought to be made by any decent compiler, even in C++03 mode.
Move semantics ...
- 1,475
80
votes
Can we make general statements about the performance of interpreted code vs compiled code?
Generalizations and specific scenarios are literally opposites.
You seem to be contradicting yourself. On the one hand, you want to make a general statement about interpreted vs compiled languages. ...
- 971
73
votes
Accepted
Using a different algorithm depending on the size of the input
Why don't we just use a different algorithm based on the size of the input?
We do. Hybrid algorithms are used all the time.
Why shouldn't/couldn't I make a function like this (written in pseudo-C#-...
- 104k
71
votes
What are the benefits of multi-file programming?
There are a lot of technical reasons behind using multiple files when writing large complex systems. All of them are meaningless in the face of the best reason to use multiple files:
Readability.
...
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66
votes
When to optimize for memory vs performance speed for a method?
To answer the stated question:
When to optimize for memory vs performance speed for a method?
There are two things you have to establish:
What is limiting your application?
Where can I reclaim the ...
- 46.1k
63
votes
Is it bad practice to write code that relies on compiler optimizations?
Now, I feel that the syntax is much clearer when the object is explicitly returned by value, and the compiler will generally employ the RVO and make the process more efficient. Is it bad practice to ...
- 1,308
62
votes
Accepted
In software programming, would it be possible to have both CPU and GPU loads at 100%?
Theoretically yes, but practically it's rarely worth it.
Both CPUs and GPUs are turing-complete, so any algorithm which can be calculated by one can also be calculated by the other. The question is ...
- 23.3k
60
votes
When do function call costs still matter in modern compilers?
Function call overhead depends entirely on the language, and at what level you are optimizing.
On an ultra low level, function calls and even more so virtual method calls may be costly if they lead ...
- 134k
60
votes
Accepted
Does Garbage Collection Scan The Entire Memory?
I was reading a bit about garbage collectors and I am wondering if the garbage collector of a program scans the entire heap memory or what is allocated to it?
That depends on the garbage collector. ...
- 104k
53
votes
When is it better to optimize a software for better performance, at the beginning or at the end of the development?
The number one thing should always and forever be readability. If it's slow but readable, I can fix it. If it's broken but readable, I can fix it. If it's unreadable, I have to ask someone else what ...
- 109k
52
votes
Accepted
What is a realistic, real-world, maximum size for a SQLite database?
The realistic limit (of the size of some Sqlite database) is the same as the realistic limit for a data file. And that limit depends a lot of your computer & system. On my current Linux desktop I ...
- 32.7k
51
votes
Am I right that switching programming languages will have little impact on the scalability of a CRUD API?
At a global level, you're wrong - language does matter, or at the very least you will spend more $$$ on compute if you write it in a less computationally efficient language.
While I'm not at liberty ...
- 24.1k
50
votes
Working through the single responsibility principle (SRP) in Python when calls are expensive
Many potential performance concerns are not really a problem in practice. The issue you raise may be one of them. In the vernacular, we call worrying about those problems without proof that they are ...
- 200k
48
votes
Accepted
Better solutions than joining table for Many to Many?
Quote of the day:
Premature optimization is the root of all evil- C.A.R. Hoare
There is no reason to assume that the join will be slow, if you made sure that the join table is indexed on its both ...
- 77.2k
45
votes
When to optimize for memory vs performance speed for a method?
"this would reduce memory" - em, no. Even if this would be true (which, for any decent compiler is not), the difference would most probably be negligible for any real world situation.
However, I ...
- 207k
42
votes
Accepted
Am I right that switching programming languages will have little impact on the scalability of a CRUD API?
There's a good video (warning, contains really a lot of swearing, but worth it) that will give you a good basis for arguing against this consultant... Solving Imaginary Scaling Issues (at Scale), by ...
- 773
40
votes
Accepted
What are the complexities of a binary search?
The full term for this is "Time Complexity" and you'll want to use that if you are searching. This is a core concept in computer science. I am not going to attempt to explain it in detail ...
- 27.3k
37
votes
Can we make general statements about the performance of interpreted code vs compiled code?
As a rule of thumb, an interpreted program is about 2x–10x slower than writing the program in the interpreter's host language, with interpreters for more dynamic languages being slower. This is ...
- 134k
36
votes
Accepted
How to deal with misconceptions about "premature optimization is the root of all evil"?
It seems you are looking for shortcuts not to try out the "purest naive implementation" first, and directly implement a "more sophisticated solution because you know beforehand that the naive ...
- 207k
36
votes
In software programming, would it be possible to have both CPU and GPU loads at 100%?
It is not related to game programming. Some scientific code can also use both the GPU and the CPU.
With careful -and painful- programming, e.g. by using OpenCL or CUDA, you could load both your GPU ...
- 32.7k
36
votes
Accepted
Why should I use foreign keys in database?
It maintains referential integrity (yes but can be maintained without it too)
You are technically correct that if you're able to maintain referential integrity yourself, you don't need the constraint ...
- 49.8k
36
votes
Why is it necessary to mark classes as not inherited from? Can't an optimizer automatically detect that virtual calls are unnecessary?
Don't we need to take a step back here?
Under the hood, it generally all boils down to simply functions being called the with the this pointer as first arg.
It's good to question things from first ...
- 4,884
33
votes
When to optimize for memory vs performance speed for a method?
You can do better than both of those with
return (abs(a + b) > 1000);
Most processors (and hence compilers) can do abs() in a single operation. You not only have fewer sums, but also fewer ...
- 2,006
31
votes
Accepted
Is code written inline faster than using function calls?
Many language implementations will automatically inline function calls wherever this makes sense and is possible. This is completely normal for “compiled languages” like C, or JIT-compiling runtimes ...
- 134k
28
votes
Accepted
How much do function calls impact performance?
Maybe. The compiler might decide "hey, this function is only called a few times, and I'm supposed to optimize for speed, so I'll just inline this function". Essentially, the compiler will replace ...
- 514
28
votes
Accepted
how many cores should I utilize for calculations? #cores or #cores -1?
Major operating systems are mature enough to know how to handle processes which use every available core. Other processes may (and often will) be affected, but the computation won't become slower ...
- 135k
Only top scored, non community-wiki answers of a minimum length are eligible