Update memory metrics snapshot with total available memory

Author: rhamlett_microsoft

src/PerfProblemSimulator/Services/CrashService.cs

@@ -257,22 +257,27 @@ private void ExecuteOutOfMemory()
         {
             while (true)
             {
-                // Allocate pinned memory to prevent GC from moving or reclaiming it
-                var block = GC.AllocateArray<byte>(allocationSize, pinned: true);
-                
-                // Touch the memory to ensure it's committed
-                for (int i = 0; i < block.Length; i += 4096)
+                try
                 {
-                    block[i] = 0xFF;
+                    // Allocate pinned memory to prevent GC from moving or reclaiming it
+                    var block = GC.AllocateArray<byte>(allocationSize, pinned: true);
+                    
+                    // Touch the memory to ensure it's committed
+                    for (int i = 0; i < block.Length; i += 4096)
+                    {
+                        block[i] = 0xFF;
+                    }
+                    
+                    allocations.Add(block);
+                    totalAllocated += allocationSize;
+                    
+                    _logger.LogWarning("Allocated {TotalMB} MB (pinned)...", totalAllocated / (1024 * 1024));
+                }
+                catch (OutOfMemoryException)
+                {
+                    // Re-throw to be caught by outer handler
+                    throw;
                 }
-                
-                allocations.Add(block);
-                totalAllocated += allocationSize;
-                
-                _logger.LogWarning("Allocated {TotalMB} MB (pinned)...", totalAllocated / (1024 * 1024));
-
-                // Prevent GC from running during allocation loop
-                GC.TryStartNoGCRegion(allocationSize, disallowFullBlockingGC: false);
             }
         }
         catch (OutOfMemoryException)
@@ -290,10 +295,6 @@ private void ExecuteOutOfMemory()
                 "This crash was triggered by the Performance Problem Simulator to demonstrate OOM conditions.",
                 new OutOfMemoryException($"Process exhausted memory after allocating {totalAllocated / (1024 * 1024)} MB"));
         }
-        catch (InvalidOperationException)
-        {
-            // TryStartNoGCRegion can throw if already in a no-GC region - ignore and continue
-        }
     }
 
     /// <inheritdoc />

src/PerfProblemSimulator/wwwroot/css/dashboard.css

@@ -178,6 +178,12 @@ body {
     color: var(--color-text-muted);
 }
 
+.metric-total {
+    font-size: 0.7rem;
+    color: var(--color-text-muted);
+    margin-left: 0.25rem;
+}
+
 .metric-bar {
     height: 4px;
     background: #e1dfdd;

src/PerfProblemSimulator/wwwroot/index.html

@@ -50,6 +50,7 @@ <h1>🔥 Performance Problem Simulator - .NET 10 on Windows</h1>
                 <div class="metric-info">
                     <div class="metric-value" id="memoryValue">--</div>
                     <div class="metric-unit">MB</div>
+                    <div class="metric-total" id="memoryTotal"></div>
                 </div>
                 <div class="metric-bar">
                     <div class="metric-bar-fill" id="memoryBar" style="width: 0%"></div>

src/PerfProblemSimulator/wwwroot/js/dashboard.js

@@ -156,6 +156,15 @@ function handleMetricsUpdate(snapshot) {
     updateMetricCard('threads', snapshot.threadPoolThreads, 'threads', 100);
     updateMetricCard('queue', snapshot.threadPoolQueueLength, 'pending', 100);
 
+    // Update total memory display
+    const totalMemoryEl = document.getElementById('memoryTotal');
+    if (totalMemoryEl && snapshot.totalAvailableMemoryMb) {
+        const totalFormatted = snapshot.totalAvailableMemoryMb >= 1024 
+            ? (snapshot.totalAvailableMemoryMb / 1024).toFixed(1) + ' GB'
+            : Math.round(snapshot.totalAvailableMemoryMb) + ' MB';
+        totalMemoryEl.textContent = `of ${totalFormatted}`;
+    }
+
     // Update history for charts
     const timestamp = new Date(snapshot.timestamp);
     addToHistory(timestamp, snapshot);