Changeset 77336 in vbox for trunk/src/VBox

Timestamp:

Feb 15, 2019 12:56:20 PM (6 years ago)

Author:

vboxsync

Message:

EFI: Tuned the IDE/ATAPI driver for about 10x better throughput.

Location:

trunk/src/VBox/Devices/EFI/Firmware/MdeModulePkg/Bus/Ata/AtaAtapiPassThru

Files:

• AtaAtapiPassThru.c (modified) (4 diffs)
• IdeMode.c (modified) (3 diffs)

trunk/src/VBox/Devices/EFI/Firmware/MdeModulePkg/Bus/Ata/AtaAtapiPassThru/AtaAtapiPassThru.c

@@ -196 +196 @@
   switch (Mode) {
     case EfiAtaIdeMode:
+#ifdef VBOX
+      // Reading the IDE controller's PCI config space byte by byte is quite expensive.
+      // It is very unclear why it should be done again and again for every command
+      // when it was already done in IdeModeInitialization().
+      // See also ExtScsiPassThruPassThru().
+#else
       //
       // Reassign IDE mode io port registers' base addresses
@@ -204 +210 @@
         return Status;
       }
+#endif
 
       switch (Protocol) {
@@ -2027 +2034 @@
   switch (Mode) {
     case EfiAtaIdeMode:
+#ifdef VBOX
+      // Reading the IDE controller's PCI config space byte by byte is quite expensive.
+      // It is very unclear why it should be done again and again for every command
+      // when it was already done in IdeModeInitialization().
+      // See also AtaPassThruPassThruExecute().
+#else
       //
       // Reassign IDE mode io port registers' base addresses
@@ -2035 +2048 @@
         return Status;
       }
+#endif
 
       Status = AtaPacketCommandExecute (Instance->PciIo, &Instance->IdeRegisters[Port], Port, PortMultiplier, Packet);

trunk/src/VBox/Devices/EFI/Firmware/MdeModulePkg/Bus/Ata/AtaAtapiPassThru/IdeMode.c

@@ -1146 +1146 @@
   IdeWritePortB (PciIo, IdeRegisters->CmdOrStatus, AtaCommand);
 
+#ifdef VBOX
+  // Stalling is a complete waste of time in a VM. BSY gets set before the status register can be read again.
+#else
   //
   // Stall at least 400 microseconds.
   //
   MicroSecondDelay (400);
+#endif
 
   return EFI_SUCCESS;
@@ -1802 +1806 @@
     DeviceControl |= ATA_CTLREG_IEN_L;
     IdeWritePortB (PciIo, IdeRegisters->AltOrDev, DeviceControl);
+#ifdef VBOX
+    // It is not at all clear what purpose the unconditional 10 millisecond delay might possibly serve.
+#else
     //
     // Stall for 10 milliseconds.
     //
     MicroSecondDelay (10000);
+#endif
 
   }
@@ -2079 +2087 @@
   for (Count = 0; Count < 6; Count++) {
     IdeWritePortW (PciIo, IdeRegisters->Data, *((UINT16*)PacketCommand + Count));
+#ifdef VBOX
+    // Any stalling is completely unnecessary, especially in a VM.
+#else
     //
     // Stall for 10 microseconds.
     //
     MicroSecondDelay (10);
+#endif
   }