Step 4 - 二级页表 + 缺页 + FIFO

Assets/Tests/EditMode/Step4PageTableAndFifoTests.cs

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+using System;
+using NUnit.Framework;
+using VMdemo.Simulation;
+
+namespace VMdemo.Tests.EditMode
+{
+    public class Step4PageTableAndFifoTests
+    {
+        [Test]
+        public void TwoLevelPageTable_SetPresent_ThenTryGetPresentPfn_Hits()
+        {
+            var pageTable = new TwoLevelPageTable(3, 2);
+            pageTable.SetPresent(5UL, 3UL, 9UL, dirty: true);
+
+            var hit = pageTable.TryGetPresentPfn(5UL, 3UL, out var pfn);
+            var exists = pageTable.TryGetEntry(5UL, 3UL, out var entry);
+
+            Assert.IsTrue(hit);
+            Assert.That(pfn, Is.EqualTo(9UL));
+            Assert.IsTrue(exists);
+            Assert.That(entry.Present, Is.True);
+            Assert.That(entry.Dirty, Is.True);
+        }
+
+        [Test]
+        public void TwoLevelPageTable_MarkNotPresent_ThenMisses()
+        {
+            var pageTable = new TwoLevelPageTable(3, 2);
+            pageTable.SetPresent(1UL, 2UL, 7UL);
+
+            var changed = pageTable.MarkNotPresent(1UL, 2UL);
+            var changedAgain = pageTable.MarkNotPresent(1UL, 2UL);
+            var hitAfterMark = pageTable.TryGetPresentPfn(1UL, 2UL, out _);
+            var exists = pageTable.TryGetEntry(1UL, 2UL, out var entry);
+
+            Assert.IsTrue(changed);
+            Assert.IsFalse(changedAgain);
+            Assert.IsFalse(hitAfterMark);
+            Assert.IsTrue(exists);
+            Assert.IsFalse(entry.Present);
+        }
+
+        [Test]
+        public void PhysicalMemoryManager_AllocateForVpn_EvictsInFifoOrder()
+        {
+            var manager = new PhysicalMemoryManager(2UL);
+
+            var r1 = manager.AllocateForVpn(1UL);
+            var r2 = manager.AllocateForVpn(2UL);
+            var r3 = manager.AllocateForVpn(3UL); // evict 1
+            var r4 = manager.AllocateForVpn(4UL); // evict 2
+
+            Assert.That(r1.AssignedPfn, Is.EqualTo(0UL));
+            Assert.That(r2.AssignedPfn, Is.EqualTo(1UL));
+            Assert.That(r3.AssignedPfn, Is.EqualTo(0UL));
+            Assert.That(r4.AssignedPfn, Is.EqualTo(1UL));
+
+            Assert.IsFalse(r1.Eviction.HasEvicted);
+            Assert.IsFalse(r2.Eviction.HasEvicted);
+            Assert.IsTrue(r3.Eviction.HasEvicted);
+            Assert.That(r3.Eviction.EvictedVpn, Is.EqualTo(1UL));
+            Assert.That(r3.Eviction.EvictedPfn, Is.EqualTo(0UL));
+            Assert.IsTrue(r4.Eviction.HasEvicted);
+            Assert.That(r4.Eviction.EvictedVpn, Is.EqualTo(2UL));
+            Assert.That(r4.Eviction.EvictedPfn, Is.EqualTo(1UL));
+
+            var fifoOrder = manager.GetFifoVpnOrder();
+            Assert.That(fifoOrder.Count, Is.EqualTo(2));
+            Assert.That(fifoOrder[0], Is.EqualTo(3UL));
+            Assert.That(fifoOrder[1], Is.EqualTo(4UL));
+        }
+
+        [Test]
+        public void Resolve_WhenEvictionHappens_SyncsPageTableAndTlb()
+        {
+            var pageTable = new TwoLevelPageTable(4, 4);
+            var memory = new PhysicalMemoryManager(1UL);
+            var tlb = new TlbCache(4);
+
+            const ulong vpn1 = 1UL;
+            pageTable.GetIndicesFromVpn(vpn1, out var l1_1, out var l2_1);
+            var first = MemoryAccessResolver.Resolve(vpn1, l1_1, l2_1, pageTable, memory, tlb);
+
+            Assert.IsTrue(first.PageFault);
+            Assert.IsFalse(first.PageTableHit);
+            Assert.IsFalse(first.Eviction.HasEvicted);
+            Assert.IsTrue(tlb.Lookup(vpn1, out _));
+
+            var second = MemoryAccessResolver.Resolve(vpn1, l1_1, l2_1, pageTable, memory, tlb);
+            Assert.IsFalse(second.PageFault);
+            Assert.IsTrue(second.PageTableHit);
+
+            const ulong vpn2 = 2UL;
+            pageTable.GetIndicesFromVpn(vpn2, out var l1_2, out var l2_2);
+            var third = MemoryAccessResolver.Resolve(vpn2, l1_2, l2_2, pageTable, memory, tlb);
+
+            Assert.IsTrue(third.PageFault);
+            Assert.IsTrue(third.Eviction.HasEvicted);
+            Assert.That(third.Eviction.EvictedVpn, Is.EqualTo(vpn1));
+            Assert.IsFalse(tlb.Lookup(vpn1, out _));
+            Assert.IsTrue(tlb.Lookup(vpn2, out _));
+
+            pageTable.GetIndicesFromVpn(vpn1, out var evictedL1, out var evictedL2);
+            Assert.IsFalse(pageTable.TryGetPresentPfn(evictedL1, evictedL2, out _));
+            Assert.IsFalse(memory.TryGetResidentPfn(vpn1, out _));
+            Assert.IsTrue(memory.TryGetResidentPfn(vpn2, out _));
+        }
+
+        [Test]
+        public void HighVolumeAccess_N10000_RunsWithoutStateCorruption()
+        {
+            var pageTable = new TwoLevelPageTable(8, 8);
+            var memory = new PhysicalMemoryManager(16UL);
+            var tlb = new TlbCache(8);
+            var random = new Random(123);
+
+            for (var i = 0; i < 10000; i++)
+            {
+                var vpn = (ulong)random.Next(0, 512);
+                pageTable.GetIndicesFromVpn(vpn, out var l1, out var l2);
+
+                var result = MemoryAccessResolver.Resolve(vpn, l1, l2, pageTable, memory, tlb);
+                var fifoOrder = memory.GetFifoVpnOrder();
+
+                Assert.That(memory.ResidentCount, Is.LessThanOrEqualTo(16));
+                Assert.That(fifoOrder.Count, Is.EqualTo(memory.ResidentCount));
+                if (result.PageTableHit)
+                {
+                    Assert.IsFalse(result.PageFault);
+                }
+            }
+        }
+    }
+}

Assets/Tests/EditMode/Step4PageTableAndFifoTests.cs.meta

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