Changeset 105179 in vbox

Timestamp:

Jul 8, 2024 10:38:14 AM (7 months ago)

Author:

vboxsync

Message:

VMM/IEM: Introduce a small cache of recently freed TBs for immediate consumption by the allocator to reduce the amount of time required in ASMBitFirstClear()/ASMBitNextClear() to scan for freed TBs when allocating a new TB, bugref:10653

Location:

trunk/src/VBox/VMM

Files:

• VMMAll/IEMAllThrdRecompiler.cpp (modified) (2 diffs)
• include/IEMInternal.h (modified) (2 diffs)

trunk/src/VBox/VMM/VMMAll/IEMAllThrdRecompiler.cpp

@@ -946 +946 @@
     pTb->pabOpcodes         = NULL;
 
-    ASMBitClear(&pTbAllocator->bmAllocated, IEMTBALLOC_IDX_MAKE(pTbAllocator, idxChunk, idxInChunk));
+    if (pTbAllocator->idxTbCacheFree < RT_ELEMENTS(pTbAllocator->apTbFreeCache))
+        pTbAllocator->apTbFreeCache[pTbAllocator->idxTbCacheFree++] = pTb;
+    else
+        ASMBitClear(&pTbAllocator->bmAllocated, IEMTBALLOC_IDX_MAKE(pTbAllocator, idxChunk, idxInChunk));
     Assert(pTbAllocator->cInUseTbs > 0);
 
@@ -1092 +1095 @@
     Assert(pTbAllocator->cInUseTbs < pTbAllocator->cTotalTbs);
 
-    int idxTb;
-    if (pTbAllocator->iStartHint < pTbAllocator->cTotalTbs)
-        idxTb = ASMBitNextClear(pTbAllocator->bmAllocated,
-                                pTbAllocator->cTotalTbs,
-                                pTbAllocator->iStartHint & ~(uint32_t)63);
+    PIEMTB pTb;
+    if (pTbAllocator->idxTbCacheFree)
+        pTb = pTbAllocator->apTbFreeCache[--pTbAllocator->idxTbCacheFree];
     else
-        idxTb = -1;
-    if (idxTb < 0)
-    {
-        idxTb = ASMBitFirstClear(pTbAllocator->bmAllocated, pTbAllocator->cTotalTbs);
-        AssertLogRelReturn(idxTb >= 0, NULL);
-    }
-    Assert((uint32_t)idxTb < pTbAllocator->cTotalTbs);
-    pTbAllocator->iStartHint = idxTb;
-    ASMBitSet(pTbAllocator->bmAllocated, idxTb);
-
-    /** @todo shift/mask optimization for power of two IEMTB sizes. */
-    uint32_t const idxChunk     = IEMTBALLOC_IDX_TO_CHUNK(pTbAllocator, idxTb);
-    uint32_t const idxTbInChunk = IEMTBALLOC_IDX_TO_INDEX_IN_CHUNK(pTbAllocator, idxTb, idxChunk);
-    PIEMTB const   pTb          = &pTbAllocator->aChunks[idxChunk].paTbs[idxTbInChunk];
-    Assert(pTb->idxAllocChunk == idxChunk);
+    {
+        int idxTb;
+        if (pTbAllocator->iStartHint < pTbAllocator->cTotalTbs)
+            idxTb = ASMBitNextClear(pTbAllocator->bmAllocated,
+                                    pTbAllocator->cTotalTbs,
+                                    pTbAllocator->iStartHint & ~(uint32_t)63);
+        else
+            idxTb = -1;
+        if (idxTb < 0)
+        {
+            idxTb = ASMBitFirstClear(pTbAllocator->bmAllocated, pTbAllocator->cTotalTbs);
+            AssertLogRelReturn(idxTb >= 0, NULL);
+        }
+        Assert((uint32_t)idxTb < pTbAllocator->cTotalTbs);
+        pTbAllocator->iStartHint = idxTb;
+        ASMBitSet(pTbAllocator->bmAllocated, idxTb);
+
+        /** @todo shift/mask optimization for power of two IEMTB sizes. */
+        uint32_t const idxChunk     = IEMTBALLOC_IDX_TO_CHUNK(pTbAllocator, idxTb);
+        uint32_t const idxTbInChunk = IEMTBALLOC_IDX_TO_INDEX_IN_CHUNK(pTbAllocator, idxTb, idxChunk);
+        pTb          = &pTbAllocator->aChunks[idxChunk].paTbs[idxTbInChunk];
+        Assert(pTb->idxAllocChunk == idxChunk);
+    }
 
     pTbAllocator->cInUseTbs        += 1;

trunk/src/VBox/VMM/include/IEMInternal.h

@@ -1490 +1490 @@
      *  See iemTbAllocatorFreeupNativeSpace for details. */
     uint32_t        iPruneNativeFrom;
-    uint32_t        uPadding;
+    /** Index into IEMTBALLOCATOR::aFreeCache were the next freed TB can be stored
+     * (0 means the cache is empty, 32 the cache is full). */
+    uint32_t        idxTbCacheFree;
 
     /** Statistics: Number of TB allocation calls. */
@@ -1503 +1505 @@
     /** The delayed free list (see iemTbAlloctorScheduleForFree). */
     PIEMTB          pDelayedFreeHead;
+    /* Cache of recently freed TBs for immediate consumption by the allocator. */
+    PIEMTB          apTbFreeCache[32];
 
     /** Allocation chunks. */