Optimization is the process of improving an existing program to make it work more efficiently or/and using less resources.
-1
votes
0answers
61 views
What's a good starting point to learn about JIT compilers? [on hold]
I've spent the past few months learning about stack based virtual machines, parsers, compilers, and some elementary things about hardware architecture. I've also written a few parsers and compilers ...
1
vote
1answer
45 views
Efficient algorithm for Virtual Machine(VM) Consolidation in Cloud
PROBLEM:
We have N physical machines(PMs) each with ram Ri, cpu Ci and a set of currently scheduled VMs each with ram requirement ri and ci respectively
Moving(Migrating) any VM from one PM to ...
-4
votes
1answer
86 views
Dos and don'ts for efficient software [closed]
Suppose I'm setting out to write code to run scientific simulations. It's important that this code runs as efficiently as possible. There may be design/implementation choices that impact upon this. ...
1
vote
2answers
72 views
Which is more expensive multiple conditional branches or multiple relational expression in a single condition?
Which is more expensive in terms of processing costs
if ( x < 20 && z == "M") {
// statements 3
}
if ( x >= 20 && w && x <= 65) {
// statements 1
}
if( x ...
1
vote
1answer
168 views
How does an optimizing compiler react to a program with nested loops?
Say you have a bunch of nested loops.
public void testMethod() {
for(int i = 0; i<1203; i++){
//some computation
for(int k=2; k<123; k++){
...
3
votes
2answers
172 views
Why isn't Haskell able to optimize infinite lists?
Lets say you've got a list
l = [0, 2..]
and you want to get the nth number when n is pretty large, say n=123456789.
So you call l !! 123456789.
On my machine, this results in out of memory.
So why ...
15
votes
11answers
6k views
Does C++ compiler remove/optimize useless parentheses?
Will the code
int a = ((1 + 2) + 3); // Easy to read
run slower than
int a = 1 + 2 + 3; // (Barely) Not quite so easy to read
or are modern compilers clever enough to remove/optimize "useless" ...
0
votes
0answers
16 views
Ant colony optimization - movement of ants [migrated]
I am trying to implement ant colony optimization. Tried to refer this paper: http://stackoverflow.com/questions/23574744/improved-ant-colony-optimization-for-robot-navigation-paper.
Since I didn't ...
0
votes
2answers
89 views
Optimization ended up in casting an object at each method call
I've been doing some optimization for the following piece of code :
public void DrawLine(int x1, int y1, int x2, int y2, int color)
{
_bitmap.DrawLineBresenham(x1, y1, x2, y2, color);
}
After ...
2
votes
2answers
90 views
Is retaining intermediate objects as member fields a good idea in this case?
I'm currently writing a series of classes in java that are meant to translate a regular expression (written with the formal definition, not language-specific shortcuts) into a deterministic finite ...
1
vote
3answers
433 views
Is there a performance difference between ++x over x++? [duplicate]
Is there a performance difference between using ++x over x++ increment operators?
I've see developers use ++x in loops where I would normally write x++ out of habit.
For example;
for(int x=0; x ...
0
votes
0answers
18 views
How do I implement the OpsDB from Release It! by Michael T Nygard
I have recently been reading the Release It! book by Michael T Nygard.In the book he talks about Implementing an OpsDB to manage and record performance statistics of applications.
Has anyone ...
0
votes
2answers
110 views
Is it fine to reuse a class instance?
I ask in terms of high cost classes, with a particle engine as an example.
I read somewhere that an instance of a class with a high cost to initialize, like a particle manager, should have its state ...
0
votes
2answers
65 views
Trying to “combine” similar objects without doing a bazillion comparisons
In this database I have "accesses" - each access can have any number (usually less than 4, sometimes as many as 15) attributes. I also have "tickets" where N users are requesting M accesses, so I've ...
0
votes
0answers
32 views
Maximize the visibility of an ad to a maximum of people in an automatic advertising system
I have N different ads that I want to display at the same time to M people in an automatic advertising system. Some people will never see some ads because they only check some specific criteria on the ...
2
votes
0answers
50 views
Performance consideration and code reduction for Templates
I'm trying to decide if this might be a good idea to help reduce the size of some of my xaml resource dictionaries on a large project. Except I'm concerned about any potential performance issues going ...
2
votes
3answers
97 views
Difference between Optimization and Scalability?
If I quote a paragraph from Wikipedia about Optimization:
In computer science, program optimization or software optimization is
the process of modifying a software system to make some aspect of ...
0
votes
0answers
21 views
Request size sweet spot?
In a client-server situation, a way to batch requests to the server, ideally to batch all requests for one page (on page load), to get the entire model view for the page and all resources in one HTTP ...
18
votes
9answers
1k views
Does OO, TDD, and Refactoring to Smaller Functions affect Speed of Code?
In Computer Science field, I have noticed a notable shift in thinking when it comes to programming. The advice as it stands now is
write smaller, more testable code
refactor existing code into ...
1
vote
0answers
82 views
How to identify performance bottlenecks in your software [duplicate]
I'm building an application with lots of components, a lot of which are third-party so I only know what I can get from their documentation.
From time to time, by pure luck, I find out one of these ...
2
votes
2answers
165 views
Implementing bussiness logic with a large number of business rules and processes
We are currently working on a project that heavily relies on a database.
Among many tables the main focus is on table "data" which is linked to another table "data_type" as many-to-one, which is then ...
0
votes
1answer
132 views
Mixing declarative & imperative code (Implicit 'unit tests' ?) [closed]
Well I'm no expert, but as a student, I'm curious about languages and their design patterns / goals.
I'd like to know, whether there are any points I miss in the following examples, and why ...
3
votes
1answer
266 views
modelling a restaurant availability search
I am looking into finding an efficient way which can scale up to thousands of restaurants, for doing a reservation search. Ideally, it would be efficient to answer queries like find a restaurant ...
1
vote
1answer
152 views
Measuring “novelty” of data
I have a heuristic in mind that should allow me to "score" data based on "novelty" that I would like to work in real-ish time.
In this case, I mean novelty in the sense that the data source is ...
1
vote
1answer
204 views
Next power of 2 for a number (in search for better “bit-twiddling” way)
I just wonder if there exists better (i.e. faster?) way to get the next
power of 2 for a given number than the following one (maybe some
better sort of "bit-twiddling" hack is possible?) ...
static ...
5
votes
4answers
1k views
How do I traverse a tree without using recursion?
I have a very large in memory node tree and need to traverse the tree. Passing the returned values of each child node to their parent node. This has to be done until all the nodes have their data ...
0
votes
3answers
447 views
Unique and primary keys on a database (mysql)
I'm having quite some doubts here... If I have a table related to username/password login how can I assure there won't be any more matches of the same username and password in the same table using ...
14
votes
2answers
429 views
Algorithm for fast tag search
The problem is the following.
There's a set of simple entities E, each one having a set of tags T attached.
Each entity might have an arbitrary number of tags.
Total number of entities is near 100 ...
0
votes
2answers
193 views
Multi regex matching — what to do to optimize it?
I have multiple regexes matching an input in greedy-first mode. All regexes are already compiled and I don't see what I can do more to speed-up things. I mean using tools coming with .Net framework.
...
3
votes
1answer
275 views
Compiler doesn't inline anything?
I've rolled my own SIMD-accelerated math library. It's gotten pretty complete, so naturally I went to conduct speed tests and optimize it.
Btw this isn't premature optimization, the lib is actually ...
2
votes
0answers
142 views
Understanding velocity update in Binary Particle Swarm Optimization
I am wondering how to interpret the velocity update in a Binary Particle Swarm Optimization (PSO). To recap the velocity update :
V(t+1) = V(t) + c1 * r1 * (XlocalBest - X(t))
+ c2 * ...
3
votes
3answers
691 views
Ordering if conditions for efficiency and clean code [closed]
This is purely a design question and the example is simple to illustrate what I am asking and there are too many permutations of more complex code to provide examples that would cover the topic. I am ...
0
votes
1answer
151 views
What are some efficient ways to set up my environment when working on a remote site?
Hello fellow Programmers,
I am still a relatively new programmer and have recently gotten my first on-campus programming position. I am the sole dev responsible for 8 domains as well as 3 small sized ...
1
vote
1answer
112 views
Optimising news fetching
I have a web scraper for scraping news from different sources in wp7. My current appraoch for doing this is:
load newspapers information from xml file.
go to the specified sections and fetch the ...
0
votes
1answer
222 views
How small is the footprint of a small C compiler?
This week I could optimize using a reduced C library that allowed a drastic shrinkage in code size - from about 60 K to about 6 K and then we could load the code in the 8 K on-chip memory of an FPGA ...
4
votes
2answers
286 views
Optimizing code generation for expressions in a compiler
I don't know if this question has a simple answer or not, but I just have to ask.
I'm reading this tutorial (I don't know if this is a well-known series, but it's name is 'Let's build a compiler!' by ...
5
votes
2answers
421 views
Larger Code is Still Faster
When compiling C code with gcc, there are compiler optimizations, some that limit code size and others create fast code.
From the -S flag, I see that the -O2/03 generates more assembly than the -Os ...
7
votes
4answers
930 views
How to find bottlenecks in an application? [duplicate]
I'm building an application with lots of components, a lot of which are third-party so I only know what I can get from their documentation.
From time to time, by pure luck, I find out one of these ...
3
votes
1answer
329 views
Does setting a function public affect the C# compiler's ability to inline the function as an optimization?
This could be either for the .NET or Mono compilers.
I know that under certain conditions the compiler can inline functions (e.g. small, single call site, etc.) as an optimization. However, if the ...
1
vote
1answer
132 views
Optimization of time-varying parameters
I need to find an optimal set of "n" parameter values that minimize an objective function (a 2-hr simulation of a system). I have looked at genetic algorithm and simulated annealing methods, but was ...
-4
votes
4answers
228 views
Which if statement requires less computation?
I have
if (!b && c || a && c)
//do action a
else
//...
Due to some internal relationship between a, b, and c. !b && c || a && c is proved to be equivalent to (! ...
3
votes
1answer
152 views
Algorithm to arrange objects so that the total length of edges between them is minimized?
We are given a list of edges between a set of N vertices. There are atmost three edges joining a vertex. We have to arrange all the vertices on a straight line with the positions numbered from 1 to N ...
0
votes
2answers
324 views
What is the exact syntax of inline?
CASE 1 (Definition and declaration in same source file)
Suppose both my prototype and definition of global function is in .cpp file. Where should I write inline keyword to make compiler know?
In ...
1
vote
1answer
231 views
What are some algorithms that can assist with reservation time scheduling?
Here's the gist of the problem: There are multiple service providers who each have their own schedules of availability. There are multiple customers who seek their services. Customers need to be able ...
1
vote
4answers
155 views
Efficient way of evaluating an array of strings then add to an array in Ruby
I am looking for an efficient way of evaluating an array of strings against a series of rules and then adding them to another array.
For example I have an array of strings:
something
a
1234
#gohere
...
3
votes
1answer
461 views
Benefits of setting PHP memory_limit to lower value for specific PHP script?
I need to execute just few lines of PHP code on every single page of my website. This PHP code does not require more than 4MB memory. That is why i want to allocate just 4MB memory to all pages by ...
3
votes
5answers
246 views
Premature optimization in deciding how to optimize?
We have a class that has been properly identified for optimization. We've done the profiling and testing, and it's a problem.
Now we have two possible approaches for optimizing this class:
There is ...
3
votes
3answers
162 views
Are there algorithims for polling optimization?
I have a web-application with an async HTTP backend, which gets called by the client by AJAX requests. The client has to start a job and then polls for the result.
I started with a simple 150ms ...
0
votes
1answer
326 views
Sum of divisors of numbers of the range ~ 10^6
I was trying to find the sum of divisors of numbers upto 106. The test cases are like of the order of 105. I have done some pre processing like
int divisors(int num)
{
int sum=0;
for(int ...
9
votes
7answers
381 views
When to start thinking about scalability? [closed]
I'm having a funny but also terrible problem. I'm about to launch a new (iPhone) app. It's a turn-based multiplayer game running on my own custom backend. But I'm afraid to launch.
For some reason, I ...
