Optimization is the process of improving an existing program to make it work more efficiently or/and using less resources.

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35 views

Get from object or use variable [closed]

Which one is better //somewhere here i have Test test = new Test(); object String name = "default"; if(test.getName() != null) name = test.getName(); or String name = "default"; String ...
0
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0answers
37 views

How do we know how good a LLVM pass is?

Is there a set of benchmarks or some specific method to evaluate LLVM passes against a criteria, such as performance, memory usage, power consumption, etc? How do we know if the improvement proposed ...
17
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6answers
533 views

How does branch prediction work, if you still have to check for the conditions?

I was reading the popular answer about Branch Prediction from http://stackoverflow.com/q/11227809/555690, and there is something confusing me: If you guessed right, it continues on. If you ...
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1answer
186 views

How to merge two functions that do same things with different variables

I have these two Javascript functions that are equal except for the variables onClickVoteUp: function (e) { var $target = $(e.target); var upvoted = this.model.get("upvoted"); var ...
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2answers
136 views

Do today's modern compilers perform run time checks?

This is regarding compilers. Do compilers perform run time dependency checks to decide to vectorize a loop ? In other words, do compilers trace through the logic as it would in run-time to ...
1
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55 views

A fast algorithm for a simple multi-objective minimization?

I have a set of n (arbitrary) integer numbers S which I want to partition into k subsets S_i each of size n/k (you can assume that k divides n). Let A be the arithmetic mean of elements of the set S. ...
2
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0answers
61 views

Loop Unfolding and Named Significant Bits

I've been writing a Parser Compiler for the last seven or so years, and I recently got to the point (yet again, never satisfied) of structuring the portion dealing with the portions of the language ...
1
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2answers
85 views

When, if ever, are basic concurrency optimizations generally made?

Lets say I need to preform the following computationally intensive task For i in range(100000000): doComplexCalculationWithNoSideEffects(i) Most people I talk to tell me that basically any ...
1
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1answer
45 views

One Script file or Multiple Script Files [closed]

I have a moderately long(for me at least) bash script file that that maintains a list of LAN users and the bandwidth each one uses. It is 199 lines with 11 functions and is already calling 3 different ...
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2answers
61 views

Should benchmarks (to compare processors performance) be compiled with optimization CFLAGS?

I need to compare performance of 2 processors and I concluded I should benchmark then with several various tests. I'm currently using linpack (HPL) (because it's still well known and used for ...
3
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2answers
68 views

get All data vs get partial data Optimization

Let's say a client makes a GET call to the server to get all the followers of some user. now the client shows a list of all the followers but the only data the list needs is: {"username" : "user", ...
3
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1answer
107 views

Deciding How To Split Up Architecture Using If Blocks

I'm having trouble deciding the best way to handle splitting up if block checks for different architectures. I may be handling the scenario completely wrong, so let me know if that is the case, or if ...
1
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1answer
252 views

In C#, performance wise, an object's size does matter when you access one of its members through a reference?

It may be a stupid question but in C#, performance wise, an object's size or complexity does matter when you access one of its members through a reference? Or only that specific member is all that ...
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2answers
210 views

When should we work on GC optimization?

So, I've learnt about how GC works and how can I monitor it via VisualVM, but my question is about why we should ever perform GC optimization? In our web project (JSF/Spring/Hibernate) we haven't ...
8
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4answers
341 views

Maintenance cost of SIMD programming code base

Question: The software industry's consensus is that clean and simple code is fundamental to the long-term viability of the code base and the organization that owns it. These properties lead to lower ...
2
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3answers
139 views

Best approach for storing huge data

I'll be handling 300,000+ users. Each user (after logging in) will be able to create lets say "folders", in each folder, users will create "name=value,name2=value2,name3=value3" entry pairs. Each name ...
0
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1answer
374 views

Designing a scalable schema for college database [closed]

I am trying to build back end for college ERP system. The system will be based on LAMP. These is the scenario: Colleges have 5 branches There are 4-6 classes in each branch. There are 80 students ...
1
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0answers
103 views

Algorithm for sport tournament bracket tree

I would like to develop a library that: receive n players in input response with the tournaments brackets in output. I would ask you what kind of algorithm I have to use to choose the correct tree ...
1
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0answers
42 views

Multiple API Calls on Web Server

I am trying to build a Tumblr Site that makes API calls to Social Network sites and return data and render on the Tumblr Site. And the thing is Tumblr doesn't allow PHP on their HTML Editor. So my ...
0
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1answer
137 views

Which algorithm best fits the following problem [closed]

I'm looking for the right algorithm to solve a specific problem. I hope that there are known algorithms that can be used. The problem definition Given a set of 'options' (~10) A session is defined ...
2
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2answers
137 views

Do we really need auto-vectorization?

I am trying to understand automatic parallelization and a special case of that is auto vectorization. As I understand it auto-vectorization is more or less: The compiler takes parts of the code which ...
2
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1answer
240 views

Quickest sorting algorithm for sorting a low number of integers

I am making a program on my spare time that I want to run as quickly as possible. The program is written in C. A large set of the procedures operate on pointers to 7 integers that are sorted by their ...
2
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2answers
189 views

How can I get better than O(N^2) space complexity for a type sequence search?

Suppose I have a type sequence through which I want to search: template <typename...> struct TypeSequence { using type = TypeSequence; }; I want to create a metafunction Search that returns ...
3
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1answer
51 views

How to diversify an optimal solution set?

If given a list of players, their salaries, and their projections, one can easily find the top 'n' projected teams (where a team is a combination of players), such that every team is under the salary ...
-1
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2answers
166 views

Does GCC optimize code to remove useless variable read operations? [closed]

I'm using GCC on ununtu 14.04. My program is written in c++ and in a case i need to check the amount of time the program needs to read a large integer array. what is the best way to do this without ...
2
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1answer
310 views

Do compilers un-inline recurrent expressions?

Does a compiler look for recurrent expressions to convert it into 'function' to reduce binary size and improve performance? Of course, the obvious answer might be "some do it, some don't", so I ask ...
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0answers
87 views

What Algorithm can be use for task allocation based on location?

What algorithm can be use for task scheduling based on location? For example there are 100 students and 5 lecturers available. Each lecturer must get same amount of student using location allocation ...
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2answers
298 views

Calculating NPath Complexity

I'm trying to calculate the NPath Complexity within a function, but I'm unsure what parts I count. My understanding is that it'll sum: If Else Else If Switch Case Default Do While Is this ...
4
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1answer
411 views

How do I add link-time optimization capabilities to my LLVM-based compiler?

I am designing and implementing a programming language, and I am using LLVM for native code generation. Among others, performance is a key feature of the language, and as such, I am looking to ...
7
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6answers
1k views

Why don't compilers inline everything? [closed]

Sometimes compilers inline function calls. That means that they move the code of the called function into the calling function. This makes things slightly faster because there's no need to push and ...
1
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2answers
183 views

How to measure algorithm accuracy?

I have a few optimization algorithms (for finding function minimum) and I'd like to check how good they are. Suppose I build test cases and compare the actual results to theoretical ones. What ...
2
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1answer
99 views

Finding a way to simplify complex queries on legacy application

I am working with an existing application built on Rails 3.1/MySql with much of the work taking place in a JavaScript interface, although the actual platforms are not tremendously relevant here, ...
2
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3answers
413 views

Best practices for geolocation

We are writing a flight search engine. We want to pre-fill the departure airport for mobile users with the closest one to their location. To do that, our plan is to Find a list of airports with ...
2
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4answers
174 views

Optimizing code by using registers, but what if they are not enough in number?

One way to optimize code is to minimize the access to arrays and use variables instead, because that way we use registers instead of loading data to cache memory. For example, if in a loop I'm going ...
4
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2answers
220 views

Deferred execution of Dispose for IDisposable objects

I'm working on an application that does lots of encryption and decryption in-application and this is probably the number-one bottleneck, so I've been spending some time making performance tweaks to ...
2
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0answers
157 views

Dynamic programming in Bin packing

Problem: Given a list L of objects of possible sizes from set S={1,2,4,8} and unlimited supply of bins of sizes 16 each and we have to use minimum possible numbers of bins to pack all objects of L. I ...
0
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1answer
163 views

Refactoring a Single Rails Model with large methods & long join queries trying to do everything

I have a working Ruby on Rails Model that I suspect is inefficient, hard to maintain, and full of unnecessary SQL join queries. I want to optimize and refactor this Model (Quiz.rb) to comply with ...
17
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3answers
394 views

How to test and optimize when you can't reproduce the environment?

In the past, I've worked in a variety of environments. Desktop apps, games, embedded stuff, web services, command line jobs, web sites, database reporting, and so on. All of these environments shared ...
0
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4answers
412 views

File exists vs. File does not exist. Is there a difference in performance?

Let's say I am checking a directory for the existence of a file, and then depending on whether or not the file exists, I act accordingly. For example, see the two Python snippets below. if ...
4
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3answers
1k views

Data Oriented Design - impractical with more than 1-2 structure “members”?

The usual example of Data Oriented Design is with the Ball structure: struct Ball { float Radius; float XYZ[3]; }; and then they make some algorithm that iterates a std::vector<Ball> ...
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1answer
473 views

get all the combination of a given set of numbers [duplicate]

I m trying to get the possible combinations of a given set of numbers say for example 123 The possible combinations would be 123 132 213 231 312 321 For this i have written a code as below - ...
1
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1answer
148 views

Memory read/write access efficiency

I've heard conflicting information from different sources, and I'm not really sure which one to believe. As such, I'll post what I understand and ask for corrections. Let's say I want to use a 2D ...
2
votes
1answer
208 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 ...
1
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2answers
117 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
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1answer
220 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++){ ...
2
votes
2answers
243 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 ...
17
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11answers
7k 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
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2answers
242 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
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2answers
130 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 ...
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3answers
845 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 ...