From 85986e9dff0e3dc7e54adf4da54a7c099c7e815f Mon Sep 17 00:00:00 2001
From: Ali Saidi <saidi@eecs.umich.edu>
Date: Tue, 5 Jun 2007 01:03:35 -0400
Subject: Clean up some of vincent's code and commit it Makes page table cache
 scheme actually work

src/mem/page_table.cc:
src/mem/page_table.hh:
    fix caching scheme to actually work and improve performance

--HG--
extra : convert_revision : 443a8d8acbee540b26affcfdfbf107b8e735d1bd
---
 src/mem/page_table.cc | 22 ++++++++--------------
 src/mem/page_table.hh | 16 ++++++++++++++++
 2 files changed, 24 insertions(+), 14 deletions(-)

diff --git a/src/mem/page_table.cc b/src/mem/page_table.cc
index 96bc23793..b29a07078 100644
--- a/src/mem/page_table.cc
+++ b/src/mem/page_table.cc
@@ -90,8 +90,6 @@ PageTable::page_check(Addr addr, int64_t size) const
 }
 
 
-
-
 void
 PageTable::allocate(Addr vaddr, int64_t size)
 {
@@ -109,12 +107,7 @@ PageTable::allocate(Addr vaddr, int64_t size)
         }
 
         pTable[vaddr] = system->new_page();
-        pTableCache[2].paddr = pTableCache[1].paddr;
-        pTableCache[2].vaddr = pTableCache[1].vaddr;
-        pTableCache[1].paddr = pTableCache[0].paddr;
-        pTableCache[1].vaddr = pTableCache[0].vaddr;
-        pTableCache[0].paddr = pTable[vaddr];
-        pTableCache[0].vaddr = vaddr;
+        updateCache(vaddr, pTable[vaddr]);
     }
 }
 
@@ -126,16 +119,16 @@ PageTable::translate(Addr vaddr, Addr &paddr)
     Addr page_addr = pageAlign(vaddr);
     paddr = 0;
 
-    if (pTableCache[0].vaddr == vaddr) {
-        paddr = pTableCache[0].paddr;
+    if (pTableCache[0].vaddr == page_addr) {
+        paddr = pTableCache[0].paddr + pageOffset(vaddr);
         return true;
     }
-    if (pTableCache[1].vaddr == vaddr) {
-        paddr = pTableCache[1].paddr;
+    if (pTableCache[1].vaddr == page_addr) {
+        paddr = pTableCache[1].paddr + pageOffset(vaddr);
         return true;
     }
-    if (pTableCache[2].vaddr == vaddr) {
-        paddr = pTableCache[2].paddr;
+    if (pTableCache[2].vaddr == page_addr) {
+        paddr = pTableCache[2].paddr + pageOffset(vaddr);
         return true;
     }
 
@@ -145,6 +138,7 @@ PageTable::translate(Addr vaddr, Addr &paddr)
         return false;
     }
 
+    updateCache(page_addr, iter->second);
     paddr = iter->second + pageOffset(vaddr);
     return true;
 }
diff --git a/src/mem/page_table.hh b/src/mem/page_table.hh
index 0e2b1f58c..64c824238 100644
--- a/src/mem/page_table.hh
+++ b/src/mem/page_table.hh
@@ -95,6 +95,22 @@ class PageTable
      */
     Fault translate(RequestPtr &req);
 
+    /**
+     * Update the page table cache.
+     * @param vaddr virtual address (page aligned) to check
+     * @param paddr physical address (page aligned) to return
+     */
+    inline void updateCache(Addr vaddr, Addr paddr)
+    {
+        pTableCache[2].paddr = pTableCache[1].paddr;
+        pTableCache[2].vaddr = pTableCache[1].vaddr;
+        pTableCache[1].paddr = pTableCache[0].paddr;
+        pTableCache[1].vaddr = pTableCache[0].vaddr;
+        pTableCache[0].paddr = paddr;
+        pTableCache[0].vaddr = vaddr;
+    }
+
+
     void serialize(std::ostream &os);
     void unserialize(Checkpoint *cp, const std::string &section);
 };
-- 
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