chore: script to measure cpu and memory usage during startup

Author: sureshg

meta/scripts/cpu-mem-viz.sh renamed to meta/scripts/bench/cpu-mem-viz.sh

@@ -0,0 +1,41 @@
+#!/bin/bash
+
+CMD="$@"
+URL="http://localhost:8080/info"
+
+# Record start time
+START_TIME=$(date +%s.%N)
+
+# Start app and get PID
+$CMD &
+PID=$!
+
+# Wait for first successful HTTP 200 response
+until curl -sf "$URL" -w "%{http_code}" -o /dev/null | grep -q "200"; do sleep 0.001; done
+
+# oha -n 1000 -c 10 "$URL"
+
+# Calculate wall time
+END_TIME=$(date +%s.%N)
+WALL_TIME=$(echo "$END_TIME - $START_TIME" | bc)
+
+# Wall Time:    |------ 1.5s ------|  (Real world elapsed time)
+# Core 1:       |██████████████████|  (100% busy = 1.5 seconds of work)
+# Core 2:       |████████████████  |  ( 70% busy = 1.1 seconds of work)
+# Cores 3-10:   |                  |  (  0% busy = idle)
+# ─────────────────────────────────────────────────────────────────────
+# Summary:
+# • Total CPU Time = 1.5 + 1.1 = 2.6 seconds ✓
+# • Current CPU% = (100% + 70%) = 170% ≈ 169% ✓
+# • Wall Time = 1.5 seconds (time that actually passed)
+#
+# Key Relationships:
+# • Multi-threaded: CPU Time > Wall Time (more work than time passed)
+# • CPU% Formula: (CPU Time ÷ Wall Time) × 100%
+# • Example: (2.6 ÷ 1.5) × 100% = 173% ≈ 169%
+# ======================================================================
+
+ps -o rss,vsz,%cpu,cputime,time -p $PID | tail -1 | awk -v wt="$WALL_TIME" '{print "Memory: " $1 " KB, CPU%: " $3 "%, CPUTime: " $4 ", WallTime: " wt "s"}'
+
+# Cleanup
+kill -9 $PID 2>/dev/null