insert full pages at the end of the queue; only override page candidate if the page is not too full

Author: daanx

ide/vs2022/mimalloc-test.vcxproj

@@ -272,14 +272,14 @@
       <SubSystem>Console</SubSystem>
     </Link>
   </ItemDefinitionGroup>
+  <ItemGroup>
+    <ClCompile Include="..\..\test\main-override-static.c" />
+  </ItemGroup>
   <ItemGroup>
     <ProjectReference Include="mimalloc.vcxproj">
       <Project>{abb5eae7-b3e6-432e-b636-333449892ea6}</Project>
     </ProjectReference>
   </ItemGroup>
-  <ItemGroup>
-    <ClCompile Include="..\..\test\main-override-static.c" />
-  </ItemGroup>
   <Import Project="$(VCTargetsPath)\Microsoft.Cpp.targets" />
   <ImportGroup Label="ExtensionTargets">
   </ImportGroup>

include/mimalloc/internal.h

@@ -571,7 +571,7 @@ static inline bool mi_page_immediate_available(const mi_page_t* page) {
 }
 
 // is more than 7/8th of a page in use?
-static inline bool mi_page_mostly_used(const mi_page_t* page) {
+static inline bool mi_page_is_mostly_used(const mi_page_t* page) {
   if (page==NULL) return true;
   uint16_t frac = page->reserved / 8U;
   return (page->reserved - page->used <= frac);

src/page-queue.c

@@ -343,7 +343,7 @@ static void mi_page_queue_enqueue_from(mi_page_queue_t* to, mi_page_queue_t* fro
 
 static void mi_page_queue_enqueue_from_full(mi_page_queue_t* to, mi_page_queue_t* from, mi_page_t* page) {
   // note: we could insert at the front to increase reuse, but it slows down certain benchmarks (like `alloc-test`)
-  mi_page_queue_enqueue_from_ex(to, from, false /* enqueue at the end of the `to` queue? */, page);
+  mi_page_queue_enqueue_from_ex(to, from, true /* enqueue at the end of the `to` queue? */, page);
 }
 
 // Only called from `mi_heap_absorb`.

src/page.c

@@ -783,7 +783,8 @@ static mi_page_t* mi_page_queue_find_free_ex(mi_heap_t* heap, mi_page_queue_t* p
         page_candidate = page;
         candidate_count = 0;
       }
-      else if (!mi_page_mostly_used(page) && page->used >= page_candidate->used) {
+      // prefer to reuse fuller pages (in the hope the less used page gets freed)
+      else if (page->used >= page_candidate->used && !mi_page_is_mostly_used(page) && !mi_page_is_expandable(page)) {
         page_candidate = page;
       }
       // if we find a non-expandable candidate, or searched for N pages, return with the best candidate

test/test-stress.c

@@ -319,7 +319,7 @@ int main(int argc, char** argv) {
   mi_collect(true);
   #endif  
 #endif
-  //mi_stats_print(NULL);
+  mi_stats_print(NULL);
   //bench_end_program();
   return 0;
 }