some more careful caching prevention
This commit is contained in:
Florian Stecker
parent
874caff8b6
commit
feadef4723
96
src/main.rs
96
src/main.rs
@ -1,90 +1,112 @@
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use std::time::{Duration, Instant};
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use rand::random;
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use rand::{Rng, thread_rng, random};
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fn main() {
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for i in 1..400 {
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let result = test_searches(500000 / i, i*2);
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println!("{} {} {}",
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result[0].as_nanos(), result[1].as_nanos(), result[2].as_nanos());
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// generate 800MB of random data
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let mut data: Vec<u64> = vec![0; 100*1024*1024];
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thread_rng().fill(&mut data[..]);
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let mut metadata: Vec<(usize, usize)> = Vec::new();
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let mut all_times: Vec<Vec<(u128, u128, u128)>> = Vec::new();
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for run in 0..4 {
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let mut run_times: Vec<(u128, u128, u128)> = Vec::with_capacity(200);
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for i in 0..200 {
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let runs = 10000000 / (i+1);
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let items = (i+1)*2;
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let result = test_searches(&data, runs, items);
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if run == 0 {
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metadata.push((runs, items));
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}
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run_times.push((result[0].as_nanos(), result[1].as_nanos(), result[2].as_nanos()));
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}
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all_times.push(run_times);
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}
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for i in 0..metadata.len() {
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println!("{} {} {} {} {}",
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metadata[i].0, metadata[i].1,
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all_times.iter().map(|x|x[i].0).sum::<u128>(),
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all_times.iter().map(|x|x[i].1).sum::<u128>(),
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all_times.iter().map(|x|x[i].2).sum::<u128>());
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}
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}
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fn test_searches(runs: usize, items: usize) -> Vec<Duration> {
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let mut lists: Vec<Vec<u64>> = Vec::new();
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let mut needles: Vec<u64> = Vec::new();
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for _ in 0..runs {
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let mut current_list: Vec<u64> = Vec::new();
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for _ in 0..items {
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current_list.push(random::<u64>());
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}
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needles.push(current_list[0]);
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current_list.sort();
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lists.push(current_list);
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}
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fn test_searches(data: &[u64], runs: usize, items: usize) -> Vec<Duration> {
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let needle_offset = random::<u64>();
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// let offset_offset = random::<usize>();
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let offset_offset = items;
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flush_caches();
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let start_time = Instant::now();
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for i in 0..runs {
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search_linear_functional(&lists[i], needles[i]);
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let offset = usize::wrapping_mul(i+1, offset_offset) % (data.len() - items);
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let needle = u64::wrapping_mul((i+1) as u64, needle_offset);
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search_linear_iter(&data[offset..offset+items], needle);
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}
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let linear_functional_duration = Instant::now().duration_since(start_time);
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let linear_iter_duration = Instant::now().duration_since(start_time);
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flush_caches();
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let start_time = Instant::now();
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for i in 0..runs {
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search_linear_naive(&lists[i], needles[i]);
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let offset = usize::wrapping_mul(i+1, offset_offset) % (data.len() - items);
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let needle = u64::wrapping_mul((i+1) as u64, needle_offset);
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search_linear_loop(&data[offset..offset+items], needle);
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}
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let linear_naive_duration = Instant::now().duration_since(start_time);
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let linear_loop_duration = Instant::now().duration_since(start_time);
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flush_caches();
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let start_time = Instant::now();
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for i in 0..runs {
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search_binary(&lists[i], needles[i]);
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let offset = usize::wrapping_mul(i+1, offset_offset) % (data.len() - items);
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let needle = u64::wrapping_mul((i+1) as u64, needle_offset);
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search_binary(&data[offset..offset+items], needle);
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}
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let binary_duration = Instant::now().duration_since(start_time);
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eprintln!("Tested {} runs of {} items each", runs, items);
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vec![linear_functional_duration, linear_naive_duration, binary_duration]
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vec![linear_iter_duration, linear_loop_duration, binary_duration]
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}
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fn flush_caches() {
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let mut rnd: Vec<u64> = Vec::new();
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let mut data: Vec<u64> = vec![0; 1024*1024];
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thread_rng().fill(&mut data[..]);
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for _ in 0..10*1024*1024 {
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rnd.push(random::<u64>());
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}
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for i in 0..10*1024*1024 {
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if rnd[i] == i as u64 {
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for i in 0..data.len() {
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if data[i] == i as u64 {
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eprintln!("that's a strange coincidence!");
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}
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}
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}
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fn search_binary(haystack: &[u64], needle: u64) {
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let index = haystack.binary_search(&needle).unwrap();
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let index = haystack.binary_search(&needle).unwrap_or_else(|x|x);
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if index as u64 == needle {
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eprintln!("that's a strange coincidence!");
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}
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}
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fn search_linear_functional(haystack: &[u64], needle: u64) {
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let index = haystack.iter().enumerate().skip_while(|(_,x)|**x != needle).next().unwrap().0;
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fn search_linear_iter(haystack: &[u64], needle: u64) {
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let index = haystack.iter()
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.enumerate()
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.skip_while(|(_,x)|**x != needle)
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.next()
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.map(|x|x.0)
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.unwrap_or_else(||haystack.len());
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if index as u64 == needle {
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eprintln!("that's a strange coincidence!");
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}
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}
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fn search_linear_naive(haystack: &[u64], needle: u64) {
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fn search_linear_loop(haystack: &[u64], needle: u64) {
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let mut index = 0;
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for i in 0..haystack.len() {
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if haystack[i] == needle {
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34
times.plt
34
times.plt
@ -1,35 +1,15 @@
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set log x
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set log y
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set xrange [1:1000]
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set yrange [1:1000]
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set yrange [1:3000]
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set grid
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set terminal pngcairo size 1024, 1024
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set output "times.png"
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# plot "data_new" using (($0+1)*2):($1*1.0/(500000/($0+1))) w l lw 2 lc 1 t "linear, iterator", \
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# "data_new" using (($0+1)*2):($2*1.0/(500000/($0+1))) w l lw 2 lc 2 t "linear, for loop", \
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# "data_new" using (($0+1)*2):($3*1.0/(500000/($0+1))) w l lw 2 lc 3 t "binary", \
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# "data_new2" using (($0+1)*2):($1*1.0/(500000/($0+1))) w l lw 2 lc 1 t "", \
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# "data_new2" using (($0+1)*2):($2*1.0/(500000/($0+1))) w l lw 2 lc 2 t "", \
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# "data_new2" using (($0+1)*2):($3*1.0/(500000/($0+1))) w l lw 2 lc 3 t "", \
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# "data_new3" using (($0+1)*2):($1*1.0/(500000/($0+1))) w l lw 2 lc 1 t "", \
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# "data_new3" using (($0+1)*2):($2*1.0/(500000/($0+1))) w l lw 2 lc 2 t "", \
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# "data_new3" using (($0+1)*2):($3*1.0/(500000/($0+1))) w l lw 2 lc 3 t "", \
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# "data_new4" using (($0+1)*2):($1*1.0/(500000/($0+1))) w l lw 2 lc 1 t "", \
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# "data_new4" using (($0+1)*2):($2*1.0/(500000/($0+1))) w l lw 2 lc 2 t "", \
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# "data_new4" using (($0+1)*2):($3*1.0/(500000/($0+1))) w l lw 2 lc 3 t "", \
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plot "data_new_avg" using (($0+1)*2):($1) w l lw 2 lc 1 t "linear search, iterator", \
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"data_new_avg" using (($0+1)*2):($2) w l lw 2 lc 2 t "linear search, loop", \
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"data_new_avg" using (($0+1)*2):($3) w l lw 2 lc 3 t "binary search", \
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# plot "data" using (($0+1)*1 ):($1/($0+1)/10000) w p pt 7 lc 1 t "linear functional", \
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# "data" using (($0+1)*1 ):($2/($0+1)/10000) w p pt 7 lc 2 t "linear naive", \
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# "data" using (($0+1)*1 ):($3/($0+1)/10000) w p pt 7 lc 3 t "binary", \
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# "data_big" using (($0+1)*100):($1/($0+1)/1000000) w p pt 7 lc 1 t "", \
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# "data_big" using (($0+1)*100):($2/($0+1)/1000000) w p pt 7 lc 2 t "", \
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# "data_big" using (($0+1)*100):($3/($0+1)/1000000) w p pt 7 lc 3 t ""
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# pause mouse keypress
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# reread
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plot "data_c8" using 2:($3/$1/4) w l lw 2 t "linear, iterator, consecutive", \
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"" using 2:($4/$1/4) w l lw 2 t "linear, loop, consecutive", \
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"" using 2:($5/$1/4) w l lw 2 t "binary, consecutive", \
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"data_c7" using 2:($3/$1/4) w l lw 2 t "linear, iterator, spread", \
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"" using 2:($4/$1/4) w l lw 2 t "linear, loop, spread", \
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"" using 2:($5/$1/4) w l lw 2 t "binary, spread"
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