Changeset 97925 in vbox for trunk/src/VBox/Additions/common

Timestamp:

Dec 30, 2022 11:00:05 PM (2 years ago)

Author:

vboxsync

Message:

Add/VBoxGuestR0LibPhysHeap.cpp: Use the term 'unlink' rather than 'exclude' for removing a block/chunk from a linked list. Docs updates.

File:

• trunk/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR0LibPhysHeap.cpp (modified) (10 diffs)

trunk/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR0LibPhysHeap.cpp

@@ -36 +36 @@
 
 #include <iprt/assert.h>
+#include <iprt/err.h>
+#include <iprt/mem.h>
 #include <iprt/semaphore.h>
-#include <iprt/alloc.h>
 
 /** @page pg_vbglr0_phys_heap   VBoxGuestLibR0 - Physical memory heap.
@@ -46 +47 @@
  * (VBGLDATA::pFreeBlocksHead) doubly linked lists.
  *
- * When allocating a block, we search in Free linked list for a suitable free
- * block.  If there is no such block, a new chunk is allocated and the new block
- * is taken from the new chunk as the only chunk-sized free block. Allocated
- * block is excluded from the Free list and goes to Alloc list.
- *
- * When freeing block, we check the pointer and then exclude block from Alloc
- * list and move it to free list.
- *
- * For each chunk we maintain the allocated blocks counter.  If 2 (or more)
- * entire chunks are free they are immediately deallocated, so we always have at
- * most 1 free chunk.
+ * When allocating a block, we search the free list for a suitable free block.
+ * If there is no such block, a new chunk is allocated and the new block is
+ * taken from the new chunk as the only chunk-sized free block. The allocated
+ * block is unlinked from the free list and goes to alloc list.
+ *
+ * When freeing block, we check the pointer and then unlink the block from the
+ * alloc list and move it to the free list.
+ *
+ * For each chunk we maintain the allocated blocks counter (as well as a count
+ * of free blocks).  If 2 (or more) entire chunks are free they are immediately
+ * deallocated, so we always have at most 1 free chunk.
  *
  * When freeing blocks, two subsequent free blocks are always merged together.
- * Current implementation merges blocks only when there is a block after the
- * just freed one.
+ * Current implementation merges blocks only when there is a free block after
+ * the just freed one, never when there is one before it as that's too
+ * expensive.
  */
 
@@ -298 +300 @@
  * This also update the per-chunk block counts.
  */
-static void vbglPhysHeapExcludeBlock(VBGLPHYSHEAPBLOCK *pBlock)
+static void vbglPhysHeapUnlinkBlock(VBGLPHYSHEAPBLOCK *pBlock)
 {
     bool const fAllocated = pBlock->fAllocated;
@@ -401 +403 @@
     VBGL_PH_dprintf(("Deleting chunk %p size %x\n", pChunk, pChunk->cbSize));
 
-    /* first scan the chunk and exclude (unlink) all blocks from the lists */
+    /* first scan the chunk and unlink all blocks from the lists */
 
     uEnd = (uintptr_t)pChunk + pChunk->cbSize;
@@ -412 +414 @@
         uCur += pBlock->cbDataSize + sizeof(VBGLPHYSHEAPBLOCK);
 
-        vbglPhysHeapExcludeBlock(pBlock);
+        vbglPhysHeapUnlinkBlock(pBlock);
     }
 
     VBGL_PH_ASSERT_MSG(uCur == uEnd, ("uCur = %p, uEnd = %p, pChunk->cbSize = %08X\n", uCur, uEnd, pChunk->cbSize));
 
-    /* Exclude chunk from the chunk list */
+    /* Unlink the chunk from the chunk list. */
     if (pChunk->pNext)
         pChunk->pNext->pPrev = pChunk->pPrev;
@@ -548 +550 @@
          * it in the allocated list.
          */
-        vbglPhysHeapExcludeBlock(pBlock);
+        vbglPhysHeapUnlinkBlock(pBlock);
         pBlock->fAllocated = true;
         vbglPhysHeapInsertBlock(NULL, pBlock);
@@ -619 +621 @@
              */
             VBGL_PH_dprintf(("VbglR0PhysHeapFree: %p size %#x\n", pv, pBlock->cbDataSize));
-            vbglPhysHeapExcludeBlock(pBlock);
-
-            dumpheap("post exclude");
+            vbglPhysHeapUnlinkBlock(pBlock);
+
+            dumpheap("post unlink");
 
             pBlock->fAllocated = false;
@@ -648 +650 @@
 
                 /* Unlink the following node and invalid it. */
-                vbglPhysHeapExcludeBlock(pNeighbour);
+                vbglPhysHeapUnlinkBlock(pNeighbour);
 
                 pNeighbour->u32Signature = ~VBGL_PH_BLOCKSIGNATURE;
@@ -673 +675 @@
                         if (cUnusedChunks > 1)
                         {
-                            /* Delete current chunk, it will also exclude all free blocks
+                            /* Delete current chunk, it will also unlink all free blocks
                              * remaining in the chunk from the free list, so the pBlock
                              * will also be invalid after this.
@@ -851 +853 @@
     if (pBlock)
         return RTSemFastMutexCreate(&g_vbgldata.mutexHeap);
-    return VERR_NO_MEMORY;
+    return VERR_NO_CONT_MEMORY;
 }