Questions tagged [performance]

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11
votes
2answers
7k views

Fast hashing: combination of different techniques to identify changes in a file?

I want to create a fast way to detect whether a file might or might not be the same. For almost 100% sureness I would use an existing hash algorithm, e.g. SHA256. However, the files are expected to be ...
0
votes
1answer
333 views

Task Manager Performance tab in windows [closed]

I do not understand the following options in windows. Could any one explain
4
votes
2answers
746 views

How to avoid column wise access in matrix multiplication?

I know when we access elements in rows it will be much faster than if it is accessed column wise. In matrix multiplication one of the matrices must be accessed column wise. In GPUs with CUDA/OpenCL ...
1
vote
1answer
56 views

Applications affected by memory performance

I'm writing a paper on the topic of applications affected more by memory performance than processor performance. I've got a lot written regarding the gap between the two, however I can't seem to find ...
2
votes
1answer
688 views

Tree flattening with layout guarantees

I want to flatten a binary tree into a linear array, and I wonder if there are specific algorithms to improve locality in the linearized representation (for instance, ensuring that all data from the ...
4
votes
1answer
5k views

Performance of row- vs. column-wise matrix traversal

Scott Meyers describes here that traversing a symmetric matrix row-wise performes significantly better over traversing it column-wise - which is also significantly counter-intuitive. The reasoning ...
0
votes
0answers
38 views

What are these notations O(1)/O(n)/O(log n)? [duplicate]

I am a newbie here I recently read tutorials on java about collection framework. The time complexity of various objects in reading/writing data What does it mean? ...
0
votes
2answers
227 views

What does it mean when a computer runs 'faster'?

If you have two computers with only one thread, a and b. And computer a runs twice as fast as computer b. Does this mean that computer a and can do twice as many operations in a given time in ...
6
votes
1answer
387 views

Is the memory-runtime tradeoff an equivalent of Heisenberg's uncertainty principle?

When I work on an algorithm to solve a computing problem, I often experience that speed can be increased by using more memory, and memory usage can be decreased at the price of increased running time, ...
2
votes
2answers
775 views

Regarding to the speed of supercomputer

There seems to be a sense of competition in creating the fastest computer in the world, and I feel like technically you just have to continue increasing the core number to gain more flops, which is ...
2
votes
1answer
88 views

performance between the data structures

I have developed two existing data structures and I want to see their performances over a certain algorithm. In this case I use Dijkstra's algorithm with binary and Fibonacci heaps. Just to ask, if I ...
0
votes
1answer
25 views

VAR autoincrement with constant space consumption for super large tables

Assume there was a database system that had a data type called VARINT or some variant that allowed instead of fixed-length INTs ...
2
votes
1answer
78 views

Optimization of Hierarchical Data Propagation

I have a system in existence which works on parent-child model. They share common attributes, as they belong to same class. A parent can enforces certain data on any user selected attribute, and the ...
8
votes
3answers
3k views

Finding maximum and minimum of consecutive XOR values

Given an integer array (maximum size 50000), I have to find the minimum and maximum $X$ such that $X = a_p \oplus a_{p+1} \oplus \dots \oplus a_q$ for some $p$, $q$ with $p \leq q$. I have tried this ...
2
votes
0answers
98 views

Determine interference factors in parallel computing

Parallel processes interfere with each other in many ways, by competing for shared resources such as shared caches, memory, disks, etc. Would it be possible to determine latent factors just with a ...
0
votes
0answers
51 views

How to generate inputs to evaluate the performance of an implementation?

How can we assert that the performance of an implementation matches the expected performance defined in terms of Big-$\mathcal{O}$ and friends by generating best/worst case inputs? I'm thinking of a ...
4
votes
2answers
2k views

Theoretical speed gain of quad core vs. single core

I first asked this question at cstheory, but they suggested to ask my question here, so here it goes ... I'm working on my masters thesis and I need to have theoretical value of the (average) speed ...
9
votes
4answers
10k views

A faster, leaner JavaScript for scientific computing: what features should I keep?

Here I'm really interested in lowering barriers to mathematical education. Target: I'd like to see created for the JavaScript community, an equivalent of the Python-based/linked scientific and high-...

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