Ticket #7742: swap-kernel-v2.diff

src/system/kernel/vm/VMAnonymousCache.cpp

@@ -1493 +1493 @@
 
     if (swapAutomatic) {
         swapEnabled = true;
-        swapSize = (off_t)vm_page_num_pages() * B_PAGE_SIZE * 2;
+        swapSize = (off_t)vm_page_num_pages() * B_PAGE_SIZE;
+        if (swapSize <= (1024 * 1024 * 1024)) {
+            // Memory under 1GB? double the swap
+            swapSize *= 2;
+        }
     }
 
     if (!swapEnabled || swapSize < B_PAGE_SIZE)
@@ -1557 +1561 @@
     const char* swapPath = path.Path();
 
     // Swap size limits prevent oversized swap files
-    off_t existingSwapSize = 0;
-    struct stat existingSwapStat;
-    if (stat(swapPath, &existingSwapStat) == 0)
-        existingSwapSize = existingSwapStat.st_size;
-
-    off_t freeSpace = info.free_blocks * info.block_size + existingSwapSize;
-    off_t maxSwap = freeSpace;
     if (swapAutomatic) {
+        off_t existingSwapSize = 0;
+        struct stat existingSwapStat;
+        if (stat(swapPath, &existingSwapStat) == 0)
+            existingSwapSize = existingSwapStat.st_size;
+
+        off_t freeSpace = info.free_blocks * info.block_size + existingSwapSize;
+
         // Adjust automatic swap to a maximum of 25% of the free space
-        maxSwap = (off_t)(0.25 * freeSpace);
-    } else {
-        // If user specified, leave 10% of the disk free
-        maxSwap = freeSpace - (off_t)(0.10 * freeSpace);
-        dprintf("%s: Warning: User specified swap file consumes over 90%% of "
-            "the available free space, limiting to 90%%\n", __func__);
+        if (swapSize > (freeSpace / 4))
+            swapSize = (freeSpace / 4);
     }
 
-    if (swapSize > maxSwap)
-        swapSize = maxSwap;
-
     // Create swap file
     int fd = open(swapPath, O_RDWR | O_CREAT | O_NOCACHE, S_IRUSR | S_IWUSR);
     if (fd < 0) {