Sample maximum memory (RAM) pressure on Linux or macOS

memory_pressure.sh

#!/bin/bash
# Process tree memory peak monitor (samples at 10 Hz) for a given command.
# Works on Linux (uses PSS) and macOS (uses RSS)
#
# Usage:
#  ./memory_pressure.sh /path/to/executable [arguments...]
#
# Alternative:
# for Linux only, one could use Cgroups v2 to track memory usage of the process tree

if [ $# -eq 0 ]; then
  echo "Usage: $0 <command> [args...]"
  exit 1
fi

OS="$(uname)"
echo "Starting benchmark on $OS and monitoring memory peak..."

"$@" &
PID=$!

max_mem=0

while kill -0 $PID 2>/dev/null; do
  # Get all child PIDs (including the main one)
  CHILDREN=$(pgrep -P "$PID" 2>/dev/null | tr '\n' ' ')
  PIDS="$PID $CHILDREN"

  if [ "$OS" = "Linux" ]; then
    # On Linux: use PSS (avoids overcounting shared memory)
    current_mb=$(awk '
      BEGIN {sum=0}
      /Pss:/ {sum += $2}
      END {printf "%.1f", sum / 1024}
    ' /proc/$PIDS/smaps 2>/dev/null || echo 0)
  else
    # Sum RSS (in KB) for the whole tree and convert to MiB
    current_mb=$(ps -o rss= -p $PIDS 2>/dev/null | awk '{sum += $1} END {printf "%.1f", sum / 1024}')
  fi

  if (( $(echo "$current_mb > $max_mem" | bc -l 2>/dev/null || echo 0) )); then
    max_mem=$current_mb
    printf "\rNew peak: %6.1f MiB" "$max_mem"
  fi

  sleep 0.1
  # 10 Hz sampling rate to catch short spikes without overwhelming the system
done

echo -e "\n\n=== Benchmark finished ===\nPeak memory usage (RSS) of process tree: ${max_mem} MiB"

peak_child.sh

#!/bin/bash
# Peak memory usage estimate for top-level process and biggest single child
# not suitable for multiple child processes like "mpiexec" or "python -m torch.distributed.launch"
# Usage:
#  ./peak_child.sh /path/to/executable [arguments...]

if [[ "$(uname)" == "Darwin" ]]; then
  /usr/bin/time -l "$@" 2>&1 | \
    awk '/maximum resident set size/ {printf "Peak RSS: %.1f MiB\n", $1/1024/1024}'
else
  /usr/bin/time -v "$@" 2>&1 | \
    awk '/Maximum resident set size/ {printf "Peak RSS: %.1f MiB\n", $6/1024}'
fi