Benchmark Glium texture upload performance

bench_texture_upload.rs

#![feature(test)]

#[macro_use]
extern crate glium;
extern crate test;

use glium::DisplayBuild;
use glium::glutin;

fn fill_image() -> Vec<u8> {
    let mut vec = Vec::with_capacity(1024 * 1024 * 4);
    vec.resize(1024 * 1024 * 4, 0);
    vec
}

#[bench]
fn bench_fill_texture(b: &mut test::Bencher) {
    b.iter(|| {
        test::black_box(fill_image());
    });
}

#[bench]
fn bench_upload_texture(b: &mut test::Bencher) {
    // building the display, ie. the main object
    let display = glutin::WindowBuilder::new()
        .with_vsync()
        .build_glium()
        .unwrap();

    b.iter(|| {
        let image: Vec<u8> = fill_image();
        let image = glium::texture::RawImage2d::from_raw_rgba(image, ((1024, 1024)));
        let texture = glium::Texture2d::new(&display, image).unwrap();
    });
}

results.txt

CPU: Intel® Core™ i7-6700HQ CPU @ 2.60GHz × 8
GPU: Intel® HD Graphics 530 (Skylake GT2)
Graphics driver: xf86-video-intel / mesa

running 2 tests
test bench_fill_texture   ... bench:     690,454 ns/iter (+/- 123,167)
test bench_upload_texture ... bench:   3,653,785 ns/iter (+/- 2,256,557)

Conclusion: texture upload takes ~3 ms?!