Add staged NVIDIA burn ramp-up mode

iso/overlay/usr/local/bin/bee-john-gpu-stress

@@ -2,6 +2,7 @@
 set -eu
 
 DURATION_SEC=300
+STAGGER_SECONDS=0
 DEVICES=""
 EXCLUDE=""
 FORMAT=""
@@ -12,7 +13,7 @@ export OCL_ICD_VENDORS="/etc/OpenCL/vendors"
 export LD_LIBRARY_PATH="/usr/lib:/usr/local/lib${LD_LIBRARY_PATH:+:${LD_LIBRARY_PATH}}"
 
 usage() {
-    echo "usage: $0 [--seconds N] [--devices 0,1] [--exclude 2,3] [--format name]" >&2
+    echo "usage: $0 [--seconds N] [--stagger-seconds N] [--devices 0,1] [--exclude 2,3] [--format name]" >&2
     exit 2
 }
 
@@ -118,6 +119,7 @@ ensure_opencl_ready() {
 while [ "$#" -gt 0 ]; do
     case "$1" in
         --seconds|-t) [ "$#" -ge 2 ] || usage; DURATION_SEC="$2"; shift 2 ;;
+        --stagger-seconds) [ "$#" -ge 2 ] || usage; STAGGER_SECONDS="$2"; shift 2 ;;
         --devices) [ "$#" -ge 2 ] || usage; DEVICES="$2"; shift 2 ;;
         --exclude) [ "$#" -ge 2 ] || usage; EXCLUDE="$2"; shift 2 ;;
         --format) [ "$#" -ge 2 ] || usage; FORMAT="$2"; shift 2 ;;
@@ -170,6 +172,7 @@ done
 echo "loader=john"
 echo "selected_gpus=${FINAL}"
 echo "john_devices=${JOHN_DEVICES}"
+echo "stagger_seconds=${STAGGER_SECONDS}"
 
 cd "${JOHN_DIR}"
 
@@ -232,14 +235,21 @@ trap cleanup EXIT INT TERM
 echo "format=${CHOSEN_FORMAT}"
 echo "target_seconds=${DURATION_SEC}"
 echo "slice_seconds=${TEST_SLICE_SECONDS}"
-DEADLINE=$(( $(date +%s) + DURATION_SEC ))
+TOTAL_DEVICES=$(echo "${JOHN_DEVICES}" | tr ',' '\n' | awk 'NF' | wc -l | tr -d '[:space:]')
 _first=1
+pos=0
 for opencl_id in $(echo "${JOHN_DEVICES}" | tr ',' ' '); do
+    pos=$((pos + 1))
     [ "${_first}" = "1" ] || sleep 3
     _first=0
-    run_john_loop "${opencl_id}" "${DEADLINE}" &
+    extra_sec=$(( STAGGER_SECONDS * (TOTAL_DEVICES - pos) ))
+    deadline=$(( $(date +%s) + DURATION_SEC + extra_sec ))
+    run_john_loop "${opencl_id}" "${deadline}" &
     pid=$!
     PIDS="${PIDS} ${pid}"
+    if [ "${STAGGER_SECONDS}" -gt 0 ] && [ "${pos}" -lt "${TOTAL_DEVICES}" ]; then
+        sleep "${STAGGER_SECONDS}"
+    fi
 done
 FAIL=0
 for pid in ${PIDS}; do