nixpkgs/lib/fileset/benchmark.sh
2023-09-21 00:21:01 +02:00

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#!/usr/bin/env nix-shell
#!nix-shell -i bash -p sta jq bc nix -I nixpkgs=../..
# shellcheck disable=SC2016
# Benchmarks lib.fileset
# Run:
# [nixpkgs]$ lib/fileset/benchmark.sh HEAD
set -euo pipefail
shopt -s inherit_errexit dotglob
if (( $# == 0 )); then
echo "Usage: $0 HEAD"
echo "Benchmarks the current tree against the HEAD commit. Any git ref will work."
exit 1
fi
compareTo=$1
SCRIPT_FILE=$(readlink -f "${BASH_SOURCE[0]}")
SCRIPT_DIR=$(dirname "$SCRIPT_FILE")
nixpkgs=$(cd "$SCRIPT_DIR/../.."; pwd)
tmp="$(mktemp -d)"
clean_up() {
rm -rf "$tmp"
}
trap clean_up EXIT SIGINT SIGTERM
work="$tmp/work"
mkdir "$work"
cd "$work"
declare -a stats=(
".envs.elements"
".envs.number"
".gc.totalBytes"
".list.concats"
".list.elements"
".nrFunctionCalls"
".nrLookups"
".nrOpUpdates"
".nrPrimOpCalls"
".nrThunks"
".sets.elements"
".sets.number"
".symbols.number"
".values.number"
)
runs=10
run() {
# Empty the file
: > cpuTimes
for i in $(seq 0 "$runs"); do
NIX_PATH=nixpkgs=$1 NIX_SHOW_STATS=1 NIX_SHOW_STATS_PATH=$tmp/stats.json \
nix-instantiate --eval --strict --show-trace >/dev/null \
--expr 'with import <nixpkgs/lib>; with fileset; '"$2"
# Only measure the time after the first run, one is warmup
if (( i > 0 )); then
jq '.cpuTime' "$tmp/stats.json" >> cpuTimes
fi
done
# Compute mean and standard deviation
read -r mean sd < <(sta --mean --sd --brief <cpuTimes)
jq --argjson mean "$mean" --argjson sd "$sd" \
'.cpuTimeMean = $mean | .cpuTimeSd = $sd' \
"$tmp/stats.json"
}
bench() {
echo "Benchmarking expression $1" >&2
#echo "Running benchmark on index" >&2
run "$nixpkgs" "$1" > "$tmp/new.json"
(
#echo "Checking out $compareTo" >&2
git -C "$nixpkgs" worktree add --quiet "$tmp/worktree" "$compareTo"
trap 'git -C "$nixpkgs" worktree remove "$tmp/worktree"' EXIT
#echo "Running benchmark on $compareTo" >&2
run "$tmp/worktree" "$1" > "$tmp/old.json"
)
read -r oldMean oldSd newMean newSd percentageMean percentageSd < \
<(jq -rn --slurpfile old "$tmp/old.json" --slurpfile new "$tmp/new.json" \
' $old[0].cpuTimeMean as $om
| $old[0].cpuTimeSd as $os
| $new[0].cpuTimeMean as $nm
| $new[0].cpuTimeSd as $ns
| (100 / $om * $nm) as $pm
# Copied from https://github.com/sharkdp/hyperfine/blob/b38d550b89b1dab85139eada01c91a60798db9cc/src/benchmark/relative_speed.rs#L46-L53
| ($pm * pow(pow($ns / $nm; 2) + pow($os / $om; 2); 0.5)) as $ps
| [ $om, $os, $nm, $ns, $pm, $ps ]
| @sh')
echo -e "Mean CPU time $newMean (σ = $newSd) for $runs runs is \e[0;33m$percentageMean% (σ = $percentageSd%)\e[0m of the old value $oldMean (σ = $oldSd)" >&2
different=0
for stat in "${stats[@]}"; do
oldValue=$(jq "$stat" "$tmp/old.json")
newValue=$(jq "$stat" "$tmp/new.json")
if (( oldValue != newValue )); then
percent=$(bc <<< "scale=100; result = 100/$oldValue*$newValue; scale=4; result / 1")
if (( oldValue < newValue )); then
echo -e "Statistic $stat ($newValue) is \e[0;31m$percent% (+$(( newValue - oldValue )))\e[0m of the old value $oldValue" >&2
else
echo -e "Statistic $stat ($newValue) is \e[0;32m$percent% (-$(( oldValue - newValue )))\e[0m of the old value $oldValue" >&2
fi
(( different++ )) || true
fi
done
echo "$different stats differ between the current tree and $compareTo"
echo ""
}
# Create a fairly populated tree
touch f{0..5}
mkdir d{0..5}
mkdir e{0..5}
touch d{0..5}/f{0..5}
mkdir -p d{0..5}/d{0..5}
mkdir -p e{0..5}/e{0..5}
touch d{0..5}/d{0..5}/f{0..5}
mkdir -p d{0..5}/d{0..5}/d{0..5}
mkdir -p e{0..5}/e{0..5}/e{0..5}
touch d{0..5}/d{0..5}/d{0..5}/f{0..5}
mkdir -p d{0..5}/d{0..5}/d{0..5}/d{0..5}
mkdir -p e{0..5}/e{0..5}/e{0..5}/e{0..5}
touch d{0..5}/d{0..5}/d{0..5}/d{0..5}/f{0..5}
bench 'toSource { root = ./.; fileset = ./.; }'
rm -rf -- *
touch {0..1000}
bench 'toSource { root = ./.; fileset = unions (mapAttrsToList (name: value: ./. + "/${name}") (builtins.readDir ./.)); }'
rm -rf -- *