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Use ndarray's parallelism features

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It's easier to read, and it also gets 10-30% perf improvement for
Driver::step
This commit is contained in:
Colin
2020-09-12 20:37:31 -07:00
parent f4cdd1240d
commit b4b0fde8af
3 changed files with 33 additions and 42 deletions
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2
Cargo.toml
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@@ -14,7 +14,7 @@ font8x8 = "0.2"
image = "0.23" image = "0.23"
imageproc = "0.21" imageproc = "0.21"
log = "0.4" log = "0.4"
ndarray = "0.13" ndarray = { version = "0.13", features = ["rayon"] }
piecewise-linear = "0.1" piecewise-linear = "0.1"
rayon = "1.4" rayon = "1.4"
y4m = "0.7" y4m = "0.7"

9
src/render.rs
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@@ -291,10 +291,15 @@ impl MultiRenderer {
pub fn render(&mut self, state: &SimState, measurements: &[Box<dyn AbstractMeasurement>]) { pub fn render(&mut self, state: &SimState, measurements: &[Box<dyn AbstractMeasurement>]) {
let max_width = 1980; //< TODO: make configurable let max_width = 1980; //< TODO: make configurable
// let max_width = 200; //let max_width = 100;
if state.width() > max_width {
let dec = (state.width() + max_width - 1) / max_width; let dec = (state.width() + max_width - 1) / max_width;
let snap = state.snapshot(dec); let snap = state.snapshot(dec);
Renderer::render(self, &snap, measurements); // XXX: measurements are messed up by rescaling
Renderer::render(self, &snap, &[]);
} else {
Renderer::render(self, &state.snapshot(1), measurements);
}
} }
} }

58
src/sim.rs
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@@ -3,7 +3,7 @@ use crate::geom::Point;
use crate::mat::{self, GenericMaterial, Material}; use crate::mat::{self, GenericMaterial, Material};
use decorum::R64; use decorum::R64;
use ndarray::Array2; use ndarray::{Array2, s, Zip};
use rayon::prelude::*; use rayon::prelude::*;
pub type SimSnapshot = SimState<mat::Static>; pub type SimSnapshot = SimState<mat::Static>;
@@ -11,6 +11,7 @@ pub type SimSnapshot = SimState<mat::Static>;
#[derive(Default)] #[derive(Default)]
pub struct SimState<M=GenericMaterial> { pub struct SimState<M=GenericMaterial> {
cells: Array2<Cell<M>>, cells: Array2<Cell<M>>,
scratch: Array2<Cell<M>>,
feature_size: R64, feature_size: R64,
step_no: u64, step_no: u64,
} }
@@ -19,6 +20,7 @@ impl<M: Material + Default> SimState<M> {
pub fn new(width: u32, height: u32, feature_size: f64) -> Self { pub fn new(width: u32, height: u32, feature_size: f64) -> Self {
Self { Self {
cells: Array2::default((height as _, width as _)), cells: Array2::default((height as _, width as _)),
scratch: Array2::default((height as _, width as _)),
feature_size: feature_size.into(), feature_size: feature_size.into(),
..Default::default() ..Default::default()
} }
@@ -29,46 +31,29 @@ impl<M: Material + Clone + Default + Send + Sync> SimState<M> {
pub fn step(&mut self) { pub fn step(&mut self) {
use consts::real::*; use consts::real::*;
let half_time_step = HALF() * self.timestep(); let half_time_step = HALF() * self.timestep();
let w = self.width() as usize;
let h = self.height() as usize;
let feature_size = self.feature_size;
let mut scratch_cells = std::mem::replace(&mut self.scratch, Default::default());
// first advance all the magnetic fields // first advance all the magnetic fields
let immute_self = &self; Zip::from(self.cells.slice(s![0..h-1, 0..w-1]))
let new_cells: Vec<Vec<_>> = (0..self.height()).into_par_iter() .and(self.cells.slice(s![0..h-1, 1..w]))
.map(|y| { .and(self.cells.slice(s![1..h, 0..w-1]))
(0..self.width()).into_iter().map(move |x| { .par_apply_assign_into(scratch_cells.slice_mut(s![0..h-1, 0..w-1]), |cell, right_cell, down_cell| {
if x+1 == immute_self.width() || y+1 == immute_self.height() {
// XXX This is not an intuitive boundary condition
Cell::default()
} else {
let cell = immute_self.get(x, y);
let right_cell = immute_self.get(x+1, y);
let down_cell = immute_self.get(x, y+1);
cell.clone().step_h(right_cell, down_cell, half_time_step.into()) cell.clone().step_h(right_cell, down_cell, half_time_step.into())
} });
}).collect()
}).collect();
for (row, mut new_row) in new_cells.into_iter().enumerate() {
self.cells.row_mut(row).as_slice_mut().unwrap().swap_with_slice(&mut new_row[..]);
}
// now advance electic fields // now advance electic fields
let immute_self = &self; Zip::from(scratch_cells.slice(s![1..h, 1..w]))
let new_cells: Vec<Vec<_>> = (0..self.height()).into_par_iter() .and(scratch_cells.slice(s![1..h, 0..w-1]))
.map(|y| { .and(scratch_cells.slice(s![0..h-1, 1..w]))
(0..self.width()).into_iter().map(move |x| { .par_apply_assign_into(self.cells.slice_mut(s![1..h, 1..w]), |cell, left_cell, up_cell| {
if x == 0 || y == 0 { cell.clone().step_e(left_cell, up_cell, half_time_step.into(), feature_size.into())
// XXX This is not an intuitive boundary condition });
Cell::default()
} else { self.scratch = scratch_cells;
let cell = immute_self.get(x, y);
let left_cell = immute_self.get(x-1, y);
let up_cell = immute_self.get(x, y-1);
cell.clone().step_e(left_cell, up_cell, half_time_step.into(), immute_self.feature_size.into())
}
}).collect()
}).collect();
for (row, mut new_row) in new_cells.into_iter().enumerate() {
self.cells.row_mut(row).as_slice_mut().unwrap().swap_with_slice(&mut new_row[..]);
}
self.step_no += 1; self.step_no += 1;
} }
@@ -111,6 +96,7 @@ impl<M: Material + Clone + Default + Send + Sync> SimState<M> {
SimState { SimState {
cells: new_cells, cells: new_cells,
scratch: Array2::default((rows as _, cols as _)),
feature_size: self.feature_size, feature_size: self.feature_size,
step_no: self.step_no, step_no: self.step_no,
} }