Changeset 39828 in vbox

Timestamp:

Jan 22, 2012 11:19:14 AM (13 years ago)

Author:

vboxsync

svn:sync-xref-src-repo-rev:

75832

Message:

AHCI: Don't always allocate new memory for the data buffers but reuse it when possible. Also use RTMemPageAlloc for page aligned memory to avoid bounce buffers during I/O

File:

• trunk/src/VBox/Devices/Storage/DevAHCI.cpp (modified) (5 diffs)

trunk/src/VBox/Devices/Storage/DevAHCI.cpp

@@ -59 +59 @@
 #include "VBoxDD.h"
 
-#define AHCI_MAX_NR_PORTS_IMPL 30
-#define AHCI_NR_COMMAND_SLOTS 32
+/** Maximum number of ports available.
+ * Spec defines 32 but we have one allocated for command completion coalescing
+ * and another for a reserved future feature.
+ */
+#define AHCI_MAX_NR_PORTS_IMPL  30
+/** Maximum number of command slots available. */
+#define AHCI_NR_COMMAND_SLOTS   32
+
+#define AHCI_MAX_ALLOC_TOO_MUCH 20
 
 /** The current saved state version. */
@@ -286 +293 @@
     /** Flags for this task. */
     uint32_t                   fFlags;
+    /** Additional memory allocation for this task. */
+    void                      *pvAlloc;
+    /** Siize of the allocation. */
+    size_t                     cbAlloc;
+    /** Number of times we had too much memory allocated for the request. */
+    unsigned                   cAllocTooMuch;
     /** Data dependent on the transfer direction. */
     union
@@ -5140 +5153 @@
 
 /**
+ * Allocates memory for the given request using already allocated memory if possible.
+ *
+ * @returns Pointer to the memory or NULL on failure
+ * @param   pAhciReq    The request to allocate memory for.
+ * @param   cb          The amount of memory to allocate.
+ */
+static void *ahciReqMemAlloc(PAHCIREQ pAhciReq, size_t cb)
+{
+    if (pAhciReq->cbAlloc > cb)
+    {
+        pAhciReq->cAllocTooMuch++;
+    }
+    else if (pAhciReq->cbAlloc < cb)
+    {
+        if (pAhciReq->cbAlloc)
+            RTMemPageFree(pAhciReq->pvAlloc, pAhciReq->cbAlloc);
+
+        pAhciReq->pvAlloc = RTMemPageAlloc(RT_ALIGN_Z(cb, _4K));
+        pAhciReq->cAllocTooMuch = 0;
+    }
+
+    return pAhciReq->pvAlloc;
+}
+
+/**
+ * Frees memory allocated for the given request.
+ *
+ * @returns nothing.
+ * @param   pAhciReq    The request.
+ */
+static void ahciReqMemFree(PAHCIREQ pAhciReq)
+{
+    if (pAhciReq->cAllocTooMuch >= AHCI_MAX_ALLOC_TOO_MUCH)
+    {
+        RTMemPageFree(pAhciReq->pvAlloc, pAhciReq->cbAlloc);
+        pAhciReq->cbAlloc = 0;
+        pAhciReq->cAllocTooMuch = 0;
+    }
+}
+
+/**
  * Copies a data buffer into the S/G buffer set up by the guest.
  *
@@ -5258 +5312 @@
               ("Allocating I/O memory for a non I/O request is not allowed\n"));
 
-    pAhciReq->u.Io.DataSeg.pvSeg = RTMemAllocZ(cbTransfer);
+    pAhciReq->u.Io.DataSeg.pvSeg = ahciReqMemAlloc(pAhciReq, cbTransfer);
     if (!pAhciReq->u.Io.DataSeg.pvSeg)
         return VERR_NO_MEMORY;
@@ -5300 +5354 @@
     }
 
-    RTMemFree(pAhciReq->u.Io.DataSeg.pvSeg);
+    ahciReqMemFree(pAhciReq);
     pAhciReq->u.Io.DataSeg.pvSeg = NULL;
     pAhciReq->u.Io.DataSeg.cbSeg = 0;