From 6c7518f4e04fad66acdff7d02d38adbf38ceaeb6 Mon Sep 17 00:00:00 2001
From: Matthew Flatt <mflatt@racket-lang.org>
Date: Sat, 12 Aug 2006 12:14:27 +0000
Subject: [PATCH] record Windows experiments

svn: r4039
---
 src/mzscheme/gc2/protect_range.c |  3 ++
 src/mzscheme/gc2/vm_win.c        | 78 ++++++++++++++++++++++++++++++--
 2 files changed, 78 insertions(+), 3 deletions(-)

diff --git a/src/mzscheme/gc2/protect_range.c b/src/mzscheme/gc2/protect_range.c
index f3a6ecbc6e..a6dfe285d8 100644
--- a/src/mzscheme/gc2/protect_range.c
+++ b/src/mzscheme/gc2/protect_range.c
@@ -7,6 +7,9 @@
 
 #ifdef _WIN32
 
+/* VirtualProtect can be used only on pages allocated at the same
+   time, so we can't collapse ranges. */
+
 # define initialize_protect_page_ranges(b, s) /* */
 # define add_protect_page_range(s, l, a, w) protect_pages(s, l, w)
 # define flush_protect_page_ranges(w) /* */
diff --git a/src/mzscheme/gc2/vm_win.c b/src/mzscheme/gc2/vm_win.c
index 90cd4115db..a9de82e3c9 100644
--- a/src/mzscheme/gc2/vm_win.c
+++ b/src/mzscheme/gc2/vm_win.c
@@ -22,12 +22,46 @@
 # define CHECK_USED_AGAINST_MAX(x) /* empty */
 #endif
 
+/* Cache doesn't seem to help in Windows: */
+#define CACHE_SLOTS 0
+
+#if CACHE_SLOTS
+typedef struct {
+  size_t len;
+  void *page;
+} alloc_cache_entry;
+
+/* First dimension is age: */
+static alloc_cache_entry cache[2][CACHE_SLOTS];
+#endif
+
 static void *malloc_pages(size_t len, size_t alignment)
 {
   CHECK_USED_AGAINST_MAX(len);
-  ACTUALLY_ALLOCATING_PAGES(len);
   LOGICALLY_ALLOCATING_PAGES(len);
 
+#if CACHE_SLOTS
+ {
+   int i, j;
+   
+   for (j = 0; j < 2; j++) {
+     for (i = 0; i < CACHE_SLOTS; i++) {
+       if (cache[j][i].len == len) {
+	 if (cache[j][i].page) {
+	   void *result = cache[j][i].page;
+	   cache[j][i].page = *(void **)result;
+	   memset(result, 0, len);
+	   return result;
+	 }
+	 break;
+       }
+     }
+   }
+ }
+#endif
+
+  ACTUALLY_ALLOCATING_PAGES(len);
+
   return (void *)VirtualAlloc(NULL, len, 
 			      MEM_COMMIT | MEM_RESERVE, 
 			      PAGE_READWRITE);
@@ -35,14 +69,49 @@ static void *malloc_pages(size_t len, size_t alignment)
 
 static void free_pages(void *p, size_t len)
 {
-  VirtualFree(p, 0, MEM_RELEASE);
-
   LOGICALLY_FREEING_PAGES(len);
+
+#if CACHE_SLOTS
+  {
+    int i;
+   
+    for (i = 0; i < CACHE_SLOTS; i++) {
+      if (!cache[0][i].len)
+	cache[0][i].len = len;
+      if (cache[0][i].len == len) {
+	*(void **)p = cache[0][i].page;
+	cache[0][i].page = p;
+	return;
+      }
+    }
+  }
+#endif
+
   ACTUALLY_FREEING_PAGES(len);
+
+  VirtualFree(p, 0, MEM_RELEASE);
 }
 
 static void flush_freed_pages(void)
 {
+#if CACHE_SLOTS
+  int i;
+  void *p, *next;
+
+  for (i = 0; i < CACHE_SLOTS; i++) {
+    if (cache[1][i].len) {
+      for (p = cache[1][i].page; p; p = next) {
+	next = *(void **)p;
+	ACTUALLY_FREEING_PAGES(cache[i].len);
+	VirtualFree(p, 0, MEM_RELEASE);
+      }
+    }
+    cache[1][i].len = cache[0][i].len;
+    cache[1][i].page = cache[0][i].page;
+    cache[0][i].len = 0;
+    cache[0][i].page = NULL;
+  }
+#endif
 }
 
 static void protect_pages(void *p, size_t len, int writeable)
@@ -56,8 +125,11 @@ typedef unsigned long size_type;
 
 static size_type determine_max_heap_size(void)
 {
+  /* FIXME: should use QueryInformationJobObject() */
+#if 0
   GCPRINT(GCOUTF, 
 	  "Don't know how to get heap size for Windows: assuming 1GB\n");
+#endif
   return (1 * 1024 * 1024 * 1024);
 }
 #endif