Fix ramp-up power bench: one task instead of N redundant tasks

RunNvidiaPowerBench already performs a full internal ramp from 1 to N
GPUs in Phase 2. Spawning N tasks with growing GPU subsets meant task K
repeated all steps 1..K-1 already done by tasks 1..K-1 — O(N²) work
instead of O(N). Replace with a single task using all selected GPUs.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

audit/internal/webui/api.go

@@ -628,8 +628,10 @@ func (h *handler) handleAPIBenchmarkNvidiaRunKind(target string) http.HandlerFun
 		}
 
 		if rampUp && len(body.GPUIndices) > 1 {
-			// Ramp-up mode: resolve GPU list, then create one task per prefix
-			// [gpu0], [gpu0,gpu1], ..., [gpu0,...,gpuN-1], each running in parallel.
+			// Ramp-up mode: RunNvidiaPowerBench internally ramps from 1 to N GPUs
+			// in Phase 2 (one additional GPU per step). A single task with all
+			// selected GPUs is sufficient — spawning N tasks with growing subsets
+			// would repeat all earlier steps redundantly.
 			gpus, err := apiListNvidiaGPUs(h.opts.App)
 			if err != nil {
 				writeError(w, http.StatusBadRequest, err.Error())
@@ -646,35 +648,27 @@ func (h *handler) handleAPIBenchmarkNvidiaRunKind(target string) http.HandlerFun
 			} else {
 				now := time.Now()
 				rampRunID := fmt.Sprintf("ramp-%s", now.UTC().Format("20060102-150405"))
-				var allTasks []*Task
-				for step := 1; step <= len(resolved); step++ {
-					subset := resolved[:step]
-					stepName := fmt.Sprintf("%s · ramp %d/%d · GPU %s", name, step, len(resolved), formatGPUIndexList(subset))
-					t := &Task{
-						ID:        newJobID("bee-bench-nvidia"),
-						Name:      stepName,
-						Target:    target,
-						Priority:  defaultTaskPriority(target, taskParams{}),
-						Status:    TaskPending,
-						CreatedAt: now,
-						params: taskParams{
-							GPUIndices:       append([]int(nil), subset...),
-							SizeMB:           body.SizeMB,
-							BenchmarkProfile: body.Profile,
-							RunNCCL:          runNCCL && step == len(resolved),
-							ParallelGPUs:     true,
-							RampStep:         step,
-							RampTotal:        len(resolved),
-							RampRunID:        rampRunID,
-							DisplayName:      stepName,
-						},
-					}
-					allTasks = append(allTasks, t)
+				taskName := fmt.Sprintf("%s · ramp 1–%d · GPU %s", name, len(resolved), formatGPUIndexList(resolved))
+				t := &Task{
+					ID:        newJobID("bee-bench-nvidia"),
+					Name:      taskName,
+					Target:    target,
+					Priority:  defaultTaskPriority(target, taskParams{}),
+					Status:    TaskPending,
+					CreatedAt: now,
+					params: taskParams{
+						GPUIndices:       append([]int(nil), resolved...),
+						SizeMB:           body.SizeMB,
+						BenchmarkProfile: body.Profile,
+						RunNCCL:          runNCCL,
+						ParallelGPUs:     true,
+						RampTotal:        len(resolved),
+						RampRunID:        rampRunID,
+						DisplayName:      taskName,
+					},
 				}
-				for _, t := range allTasks {
-					globalQueue.enqueue(t)
-				}
-				writeTaskRunResponse(w, allTasks)
+				globalQueue.enqueue(t)
+				writeTaskRunResponse(w, []*Task{t})
 				return
 			}
 		}

iso/builder/auto/config

@@ -26,7 +26,7 @@ lb config noauto \
     --mirror-bootstrap "http://mirror.mephi.ru/debian/" \
     --mirror-chroot "http://mirror.mephi.ru/debian/" \
     --mirror-binary "http://mirror.mephi.ru/debian/" \
-    --security false \
+    --security true \
     --linux-flavours "amd64" \
     --linux-packages "${LB_LINUX_PACKAGES}" \
     --memtest memtest86+ \

iso/builder/config/hooks/normal/9100-memtest.hook.binary

@@ -26,6 +26,14 @@ fail_or_warn() {
     return 0
 }
 
+# grub.cfg and live.cfg may not exist yet when binary hooks run — live-build
+# creates them after this hook (lb binary_grub-efi / lb binary_syslinux).
+# The template already has memtest entries hardcoded, so a missing config file
+# here is not an error; validate_iso_memtest() checks the final ISO instead.
+warn_only() {
+    log "WARNING: $1"
+}
+
 copy_memtest_file() {
     src="$1"
     dst_name="${2:-$(basename "$src")}"
@@ -61,15 +69,17 @@ extract_memtest_from_deb() {
 
 download_and_extract_memtest() {
     tmpdl="$(mktemp -d)"
-    ver_arg=""
     if [ -n "${MEMTEST_VERSION:-}" ]; then
-        ver_arg="=memtest86+=${MEMTEST_VERSION}"
-        log "downloading memtest86+=${MEMTEST_VERSION} from apt"
+        pkg_spec="memtest86+=${MEMTEST_VERSION}"
     else
-        log "downloading memtest86+ from apt (no version pinned)"
+        pkg_spec="memtest86+"
+    fi
+    log "downloading ${pkg_spec} from apt"
+    if ! ( cd "$tmpdl" && apt-get download "$pkg_spec" 2>/dev/null ); then
+        log "apt download failed, retrying after apt-get update"
+        apt-get update -qq >/dev/null 2>&1 || true
+        ( cd "$tmpdl" && apt-get download "$pkg_spec" 2>/dev/null ) || true
     fi
-    # shellcheck disable=SC2086
-    ( cd "$tmpdl" && apt-get download "memtest86+${ver_arg}" ) 2>/dev/null || true
     deb="$(find "$tmpdl" -maxdepth 1 -type f -name 'memtest86+*.deb' 2>/dev/null | head -1)"
     if [ -n "$deb" ]; then
         extract_memtest_from_deb "$deb"
@@ -133,7 +143,7 @@ ensure_memtest_binaries() {
 
 ensure_grub_entry() {
     [ -f "$GRUB_CFG" ] || {
-        fail_or_warn "missing ${GRUB_CFG}"
+        warn_only "missing ${GRUB_CFG} (will be created by lb binary_grub-efi from template)"
         return 0
     }
 
@@ -159,7 +169,7 @@ EOF
 
 ensure_isolinux_entry() {
     [ -f "$ISOLINUX_CFG" ] || {
-        fail_or_warn "missing ${ISOLINUX_CFG}"
+        warn_only "missing ${ISOLINUX_CFG} (will be created by lb binary_syslinux from template)"
         return 0
     }