MeasureThat.net

Run results for: Multiplying lists of vectors - SoA vs AoS vs interlaced array

What's the fastest way to process a list of vectors? Do you go the OO route, with an array of Vector() objects? Do you create a new data structure, using Float32Arrays for x, y, and z? Do you create a single Float32Array and interlace values for x, y, and z within it? Let's find out!

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Run details:
Mozilla/5.0 (Windows NT 6.1; WOW64; rv:49.0) Gecko/20100101 Firefox/49.0
Firefox 49
Windows 7
Other
8 years ago
Test name Executions per second
AoS 97.3 Ops/sec
SoA - one loop 32.3 Ops/sec
SoA - one component per loop 53.0 Ops/sec
Interlaced Array - no loop unrolling 52.5 Ops/sec
Interlaced Array - with loop unrolling 53.8 Ops/sec
AoS (bracket notation) 94.1 Ops/sec
Script Preparation code:
​x
 
var N = 1000000
​
var x = new Float32Array(N);
var y = new Float32Array(N);
var z = new Float32Array(N);
​
var interlaced = new Float32Array(3*N);
​
var vectors = [];
​
for (var i = 0, li=x.length; i < li; ++i) {
    x[i] = Math.random();
    y[i] = Math.random();
    z[i] = Math.random();
    vectors.push( {x:Math.random(), y:Math.random(), z:Math.random()} );
}
​
for (var i = 0, li=interlaced.length; i < li; ++i) {
    interlaced[i] = Math.random();
}
Tests:

  • AoS

     
    var vector;
    for (var i = 0, li=vectors.length; i < li; ++i) {
        vector = vectors[i];
        vector.x = 2 * vector.x;
        vector.y = 2 * vector.y;
        vector.z = 2 * vector.z;
    }

  • SoA - one loop

     
    for (var i = 0, li=x.length; i < li; ++i) {
        x[i] = 2 * x[i];
        y[i] = 2 * y[i];
        z[i] = 2 * z[i];
    }

  • SoA - one component per loop

     
    for (var i = 0, li=x.length; i < li; ++i) {
        x[i] = 2 * x[i];
    }
    for (var i = 0, li=y.length; i < li; ++i) {
        y[i] = 2 * y[i];
    }
    for (var i = 0, li=z.length; i < li; ++i) {
        z[i] = 2 * z[i];
    }

  • Interlaced Array - no loop unrolling

     
    for (var i = 0, li=interlaced.length; i < li; ++i) {
        interlaced[i] = 2*interlaced[i];
    }

  • Interlaced Array - with loop unrolling

     
    for (var i = 0, li=interlaced.length; i < li; i+=3) {
        interlaced[i] = 2*interlaced[i];
        interlaced[i+1] = 2*interlaced[i+1];
        interlaced[i+2] = 2*interlaced[i+2];
    }

  • AoS (bracket notation)

     
    var vector;
    for (var i = 0, li=vectors.length; i < li; ++i) {
        vector = vectors[i];
        vector['x'] = 2 * vector['x'];
        vector['y'] = 2 * vector['y'];
        vector['z'] = 2 * vector['z'];
    }