Reduce max value of "Disk cache size" to 1536MB. Closes to #4028.

src/core/preferences.cpp

@@ -1358,37 +1358,26 @@ void Preferences::setShutdownqBTWhenDownloadsComplete(bool shutdown)
 uint Preferences::diskCacheSize() const
 {
     uint size = value("Preferences/Downloads/DiskWriteCacheSize", 0).toUInt();
-
-    // When build as 32bit binary, set the maximum at less than 2GB to prevent crashes.
     // These macros may not be available on compilers other than MSVC and GCC
-#if !defined(_M_X64) && !defined(__amd64__)
-    //1800MiB to leave 248MiB room to the rest of program data in RAM
-    if (size > 1800)
-        size = 1800;
+#if defined(__x86_64__) || defined(_M_X64)
+    size = qMin(size, (uint) 4096);  // 4GiB
 #else
-    // 4GiB
-    if (size > 4 * 1024)
-        size = 4 * 1024;
+    // When build as 32bit binary, set the maximum at less than 2GB to prevent crashes
+    // allocate 1536MiB and leave 512MiB to the rest of program data in RAM
+    size = qMin(size, (uint) 1536);
 #endif
-
     return size;
 }
 
 void Preferences::setDiskCacheSize(uint size)
 {
-    uint size0 = size;
-
-#if !defined(_M_X64) && !defined(__amd64__)
-    //1800MiB to leave 248MiB room to the rest of program data in RAM
-    if (size0 > 1800)
-        size0 = 1800;
+#if defined(__x86_64__) || defined(_M_X64)
+    size = qMin(size, (uint) 4096);  // 4GiB
 #else
-    // 4GiB
-    if (size0 > 4 * 1024)
-        size0 = 4 * 1024;
+    // allocate 1536MiB and leave 512MiB to the rest of program data in RAM
+    size = qMin(size, (uint) 1536);
 #endif
-
-    setValue("Preferences/Downloads/DiskWriteCacheSize", size0);
+    setValue("Preferences/Downloads/DiskWriteCacheSize", size);
 }
 
 uint Preferences::diskCacheTTL() const

src/gui/advancedsettings.h

@@ -208,12 +208,11 @@ private slots:
         spin_cache.setMinimum(0);
         // When build as 32bit binary, set the maximum at less than 2GB to prevent crashes.
         // These macros may not be available on compilers other than MSVC and GCC
-#if !defined(_M_X64) && !defined(__amd64__)
-        //1800MiB to leave 248MiB room to the rest of program data in RAM
-        spin_cache.setMaximum(1800);
+#if defined(__x86_64__) || defined(_M_X64)
+        spin_cache.setMaximum(4096);
 #else
-        // 4GiB
-        spin_cache.setMaximum(4*1024);
+        // allocate 1536MiB and leave 512MiB to the rest of program data in RAM
+        spin_cache.setMaximum(1536);
 #endif
         spin_cache.setValue(pref->diskCacheSize());
         updateCacheSpinSuffix(spin_cache.value());