alignment with log2

src/common/fs/file.cpp

@@ -7,6 +7,7 @@
 #include <vector>
 
 #include "common/assert.h"
+#include "common/bit_util.h"
 #include "common/fs/file.h"
 #include "common/fs/fs.h"
 #ifdef ANDROID
@@ -278,13 +279,19 @@ static int PlatformMapReadOnly(IOFile& io, const char* path) {
         // a fun amount of fragmentation on the disk.
         map_flags |= MAP_NOSYNC;
 #endif
-#ifdef MAP_ALIGNED_SUPER
+#if defined(NDEBUG) && defined(MAP_NOCORE)
+        map_flags |= MAP_NOCORE;
+#endif
+#ifdef MAP_ALIGNED
         // File must be big enough that it's worth to super align. We can't just super-align every
         // file otherwise we will run out of alignments for actually important files :)
         // System doesn't guarantee a super alignment, but if it's available it will delete
         // about 3 layers(?) of the TLB tree for each read/write.
         // Again the cost of faults may make this negligible gains, but hey, we gotta work
         // what we gotta work with.
+        auto const align_log = Common::Log2Ceil64(u64(st.st_size));
+        map_flags |= align_log > 12 ? MAP_ALIGNED(align_log) : 0;
+#elif defined(MAP_ALIGNED_SUPER)
         using namespace Common::Literals;
         u64 big_file_threshold = 512_MiB;
         map_flags |= u64(st.st_size) >= big_file_threshold ? MAP_ALIGNED_SUPER : 0;