Report container CPU as a share of the machine, matching Unraid's Docker page

docker stats sums CPU across every logical processor, so Jellyfin's "227%" is
2.3 threads busy — 7% of a 32-thread host, which is what Unraid shows and what
the operator was reading. The card was printing the raw figure and colouring it
against thresholds meant for a percentage, so ordinary background work looked
like an emergency; I twice flagged Jellyfin as pegged on that basis and was
wrong both times. Divides by nproc, not the watchdog's `cores` — that field is
the physical 16 because it compares load averages, and borrowing it here would
have looked reasonable and doubled every reading.

Plugin/unraid/include/media.php

@@ -269,10 +269,26 @@ function vv_media_sessions(): array {
 // paid per page load — the background writer refreshes it every minute, so the CPU figure is at
 // most a minute stale, which is honest for a card rather than a live graph. Monitor is where live
 // belongs.
+// Logical CPUs, which is what `docker stats` divides its CPU figure by — and therefore what has to
+// be divided back out to get a share of the machine.
+//
+// Logical, not physical. This host reports 16 physical cores and 32 threads; docker's percentage is
+// summed across all 32, so dividing by 16 would double every reading. The watchdog's own `cores`
+// field is the physical 16 because it is comparing load averages, which is a different question —
+// borrowing it here would have looked reasonable and been wrong by exactly a factor of two.
+function vv_media_cpu_count(): int {
+    static $n = null;
+    if ($n !== null) return $n;
+    $n = (int)trim((string)@shell_exec('nproc 2>/dev/null'));
+    if ($n < 1) $n = max(1, (int)@substr_count((string)@file_get_contents('/proc/cpuinfo'), 'processor'));
+    return $n;
+}
+
 function vv_media_container_stats(array $names): array {
     $names = array_values(array_filter($names));
     if (!$names) return [];
 
+    $cpus = vv_media_cpu_count();
     $out  = [];
     $args = implode(' ', array_map('escapeshellarg', $names));
     $fmt  = '{{.Name}}|{{.CPUPerc}}|{{.MemUsage}}|{{.MemPerc}}';
@@ -281,8 +297,16 @@ function vv_media_container_stats(array $names): array {
         $p = explode('|', $line);
         if (count($p) < 4) continue;
         [$mUsed, $mLimit] = array_pad(array_map('trim', explode('/', $p[2])), 2, '');
+        $raw = (float)rtrim($p[1], '%');
         $out[$p[0]] = [
-            'cpu_pct'   => (float)rtrim($p[1], '%'),
+            // Share of the whole machine, so this card and Unraid's own Docker page report the
+            // same container as the same number. docker's raw figure is per-core-summed: 227% is
+            // 2.3 cores busy, which reads as an emergency on a card and is 7% of a 32-thread host.
+            // Kept alongside rather than discarded — "2.3 cores" is the useful form once you know
+            // it is not a percentage of anything.
+            'cpu_pct'   => round($raw / max(1, $cpus), 2),
+            'cpu_raw'   => $raw,
+            'cpu_cores' => round($raw / 100, 2),
             'mem_used'  => $mUsed,
             'mem_limit' => $mLimit,
             'mem_pct'   => (float)rtrim($p[3], '%'),

Plugin/unraid/pages/arrs.php

@@ -450,10 +450,12 @@ function _mediaServersSection(nodes) {
   const cards = shown.map(s => {
     const up = !!s.online;
     const dot = !up ? '#c62828' : s.pending_restart || s.update_available ? '#ffb74d' : '#4caf50';
-    // Colour the CPU against cores, not against 100%: these are containers on a 16-core host, so
-    // 145% is busy rather than broken, and 1500% would be the number that matters.
+    // cpu_pct is a share of the whole machine, matching Unraid's Docker page. Thresholds are set
+    // against that: a single container taking a quarter of the host is worth noticing, half is
+    // worth alarming about. The earlier version coloured docker's raw per-core-summed figure and
+    // called 145% alarming when it was 4.5% of a 32-thread machine.
     const cpu = s.cpu_pct;
-    const cpuCol = cpu == null ? '#555' : cpu > 400 ? '#ef5350' : cpu > 150 ? '#ffb74d' : '#888';
+    const cpuCol = cpu == null ? '#555' : cpu > 50 ? '#ef5350' : cpu > 25 ? '#ffb74d' : '#888';
 
     const flags = [];
     if (s.update_available) flags.push(['update available', '#ffb74d']);
@@ -477,7 +479,8 @@ function _mediaServersSection(nodes) {
           <div class="vv-arr-stat"><div class="vv-arr-stat-n${s.users ? '' : ' dim'}">${_n(s.users)}</div><div class="vv-arr-stat-l">Users</div></div>
           <div class="vv-arr-stat"><div class="vv-arr-stat-n${s.transcodes ? '' : ' dim'}">${_n(s.transcodes)}</div><div class="vv-arr-stat-l">Transcode</div></div>
         </div>
-        ${row('CPU', `<span style="color:${cpuCol}">${cpu == null ? '—' : cpu.toFixed(1) + '%'}</span>`)}
+        ${row('CPU', `<span style="color:${cpuCol}" title="${vvEscAttr(s.cpu_raw != null ? s.cpu_raw.toFixed(1) + '% as docker stats reports it — summed across all threads' : '')}">${cpu == null ? '—' : cpu.toFixed(1) + '%'}</span>`
+              + (s.cpu_cores ? ` <span style="color:#3a3a3a">${s.cpu_cores.toFixed(1)} cores</span>` : ''))}
         ${row('Memory', vvEscHtml(s.mem_used || '—') + (s.mem_pct != null ? ` <span style="color:#3a3a3a">${s.mem_pct.toFixed(1)}%</span>` : ''))}
         ${row('Uptime', s.uptime != null ? _uptime(s.uptime) : '—')}
         ${s.os ? row('Host OS', vvEscHtml(s.os)) : ''}