maybe fixed cpu fork logging

run_all_experiments.sh

@@ -14,13 +14,19 @@ log() {
 }
 
 count_processes() {
-  # Avoid find -regex portability issues (busybox) by using globbing on /proc.
-  ls -d /proc/[0-9]* 2>/dev/null | wc -l
+  if command -v ps >/dev/null 2>&1; then
+    ps -e -o pid= 2>/dev/null | wc -l
+  else
+    echo 0
+  fi
 }
 
 count_threads_total() {
-  # Sum Threads: from all /proc/<pid>/status entries.
-  awk '/^Threads:/ {sum+=$2} END {print sum+0}' /proc/[0-9]*/status 2>/dev/null || echo 0
+  if command -v ps >/dev/null 2>&1; then
+    ps -e -o nlwp= 2>/dev/null | awk '{sum+=$1} END {print sum+0}'
+  else
+    echo 0
+  fi
 }
 
 get_mem_kb() {
@@ -33,14 +39,11 @@ sample_process_csv() {
   local start_uptime="$3"
   local max_seconds="$4"
 
-  local clk_tck
-  clk_tck=$(getconf CLK_TCK)
-
-  local prev_uptime prev_ticks
-  prev_uptime=$(awk '{print $1}' /proc/uptime)
-  prev_ticks=0
-  if [ -r "/proc/$pid/stat" ]; then
-    prev_ticks=$(awk '{print $14 + $15}' "/proc/$pid/stat")
+  local have_pidstat=0
+  if command -v pidstat >/dev/null 2>&1; then
+    have_pidstat=1
+  else
+    log "pidstat not found; install sysstat for accurate CPU sampling"
   fi
 
   while kill -0 "$pid" 2>/dev/null; do
@@ -69,22 +72,26 @@ sample_process_csv() {
     proc_count=$(count_processes || echo 0)
     thread_total=$(count_threads_total || echo 0)
 
-    local rss=0 vsz=0 stk=0 heap=0 nlwp=0
-    if [ -r "/proc/$pid/status" ]; then
-      rss=$(awk '/^VmRSS:/ {print $2}' "/proc/$pid/status")
-      vsz=$(awk '/^VmSize:/ {print $2}' "/proc/$pid/status")
-      stk=$(awk '/^VmStk:/ {print $2}' "/proc/$pid/status")
-      heap=$(awk '/^VmData:/ {print $2}' "/proc/$pid/status")
-      nlwp=$(awk '/^Threads:/ {print $2}' "/proc/$pid/status")
-    fi
-
-    # Use ps directly to avoid zero deltas for very short-lived processes.
-    local cpu
+    # Use pidstat for CPU and ps for memory/thread metrics.
+    local cpu rss vsz nlwp
     if command -v ps >/dev/null 2>&1; then
-      cpu=$(ps -o %cpu= -p "$pid" 2>/dev/null | awk '{print $1}' || true)
+      read -r cpu rss vsz nlwp < <(ps -o %cpu=,rss=,vsz=,nlwp= -p "$pid" 2>/dev/null || echo "0 0 0 0")
+      cpu=${cpu:-0}
+      rss=${rss:-0}
+      vsz=${vsz:-0}
+      nlwp=${nlwp:-0}
+    else
+      rss=0
+      vsz=0
+      nlwp=0
+    fi
+    if [ "$have_pidstat" -eq 1 ]; then
+      cpu=$(pidstat -p "$pid" 1 1 2>/dev/null | awk -v p="$pid" '$1 ~ /^[0-9]/ && $3==p {print $8; exit}')
+      cpu=${cpu:-0.00}
     else
       cpu=0.00
     fi
+    local stk=0 heap=0
 
     printf "%s,%s,%s,%s,%s,%s,%s,%s,%s,%s,%s,%s,%s,%s,%s,%s,%s\n" \
       "$(date -Iseconds)" "$elapsed_s" "$load1" "$load5" "$load15" \
@@ -92,7 +99,6 @@ sample_process_csv() {
       "$pid" "$cpu" "${rss:-0}" "${vsz:-0}" "${stk:-0}" "${heap:-0}" "${nlwp:-0}" \
       >> "$csv"
 
-    prev_uptime=$now_uptime
     sleep 1
   done
 }