Step 3 - TLB（全相联 + LRU）

Assets/Tests/EditMode/Step3TlbCacheTests.cs

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+using NUnit.Framework;
+using VMdemo.Simulation;
+
+namespace VMdemo.Tests.EditMode
+{
+    public class Step3TlbCacheTests
+    {
+        [Test]
+        public void Constructor_CapacityLessThanOne_Throws()
+        {
+            Assert.Throws<System.ArgumentOutOfRangeException>(() => new TlbCache(0));
+            Assert.Throws<System.ArgumentOutOfRangeException>(() => new TlbCache(-1));
+        }
+
+        [Test]
+        public void TryLookup_Miss_ReturnsFalseAndCountsMiss()
+        {
+            var cache = new TlbCache(2);
+
+            var hit = cache.TryLookup(10UL, out var pfn);
+
+            Assert.IsFalse(hit);
+            Assert.That(pfn, Is.EqualTo(0UL));
+            Assert.That(cache.HitCount, Is.EqualTo(0));
+            Assert.That(cache.MissCount, Is.EqualTo(1));
+        }
+
+        [Test]
+        public void InsertOrUpdate_AndLookup_HitReturnsMappedPfn()
+        {
+            var cache = new TlbCache(2);
+            cache.InsertOrUpdate(10UL, 100UL);
+
+            var hit = cache.TryLookup(10UL, out var pfn);
+
+            Assert.IsTrue(hit);
+            Assert.That(pfn, Is.EqualTo(100UL));
+            Assert.That(cache.HitCount, Is.EqualTo(1));
+            Assert.That(cache.MissCount, Is.EqualTo(0));
+        }
+
+        [Test]
+        public void InsertOrUpdate_ExistingEntry_UpdatesPfnAndMovesToMostRecent()
+        {
+            var cache = new TlbCache(3);
+            cache.InsertOrUpdate(1UL, 11UL);
+            cache.InsertOrUpdate(2UL, 22UL);
+            cache.InsertOrUpdate(3UL, 33UL);
+
+            cache.InsertOrUpdate(1UL, 111UL);
+
+            var entries = cache.GetEntriesMostRecentFirst();
+
+            Assert.That(entries.Count, Is.EqualTo(3));
+            Assert.That(entries[0].Vpn, Is.EqualTo(1UL));
+            Assert.That(entries[0].Pfn, Is.EqualTo(111UL));
+            Assert.That(entries[1].Vpn, Is.EqualTo(3UL));
+            Assert.That(entries[2].Vpn, Is.EqualTo(2UL));
+        }
+
+        [Test]
+        public void OverCapacity_EvictsLeastRecentlyUsedEntry()
+        {
+            var cache = new TlbCache(3);
+            cache.InsertOrUpdate(1UL, 11UL);
+            cache.InsertOrUpdate(2UL, 22UL);
+            cache.InsertOrUpdate(3UL, 33UL);
+
+            cache.TryLookup(1UL, out _); // refresh 1 as MRU
+            cache.InsertOrUpdate(4UL, 44UL); // should evict 2
+
+            Assert.That(cache.Count, Is.EqualTo(3));
+            Assert.IsFalse(cache.TryLookup(2UL, out _));
+            Assert.IsTrue(cache.TryLookup(1UL, out var pfn1));
+            Assert.That(pfn1, Is.EqualTo(11UL));
+
+            var entries = cache.GetEntriesMostRecentFirst();
+            Assert.That(entries[0].Vpn, Is.EqualTo(1UL));
+            Assert.That(entries[1].Vpn, Is.EqualTo(4UL));
+            Assert.That(entries[2].Vpn, Is.EqualTo(3UL));
+        }
+
+        [Test]
+        public void Remove_ExistingAndMissingKeys_BehaveAsExpected()
+        {
+            var cache = new TlbCache(2);
+            cache.InsertOrUpdate(5UL, 55UL);
+
+            var removedFirst = cache.Remove(5UL);
+            var removedSecond = cache.Remove(5UL);
+
+            Assert.IsTrue(removedFirst);
+            Assert.IsFalse(removedSecond);
+            Assert.That(cache.Count, Is.EqualTo(0));
+        }
+
+        [Test]
+        public void Clear_ResetsEntriesAndCounters()
+        {
+            var cache = new TlbCache(2);
+            cache.InsertOrUpdate(1UL, 10UL);
+            cache.InsertOrUpdate(2UL, 20UL);
+            cache.TryLookup(1UL, out _);
+            cache.TryLookup(99UL, out _);
+
+            cache.Clear();
+
+            Assert.That(cache.Count, Is.EqualTo(0));
+            Assert.That(cache.HitCount, Is.EqualTo(0));
+            Assert.That(cache.MissCount, Is.EqualTo(0));
+            Assert.That(cache.GetEntriesMostRecentFirst().Count, Is.EqualTo(0));
+        }
+
+        [Test]
+        public void ContinuousLookup_TracksHitAndMissCountsAccurately()
+        {
+            var cache = new TlbCache(2);
+            cache.InsertOrUpdate(1UL, 10UL);
+            cache.InsertOrUpdate(2UL, 20UL);
+
+            cache.TryLookup(1UL, out _);   // hit
+            cache.TryLookup(3UL, out _);   // miss
+            cache.TryLookup(2UL, out _);   // hit
+            cache.TryLookup(3UL, out _);   // miss
+
+            Assert.That(cache.HitCount, Is.EqualTo(2));
+            Assert.That(cache.MissCount, Is.EqualTo(2));
+        }
+    }
+}

Assets/Tests/EditMode/Step3TlbCacheTests.cs.meta

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