Kernel: Add a simple slab allocator for small allocations

This is a freelist allocator with static size classes that works as a
complement to the generic kmalloc(). It's a lot faster than kmalloc()
since allocation just means popping from the freelist.

It's also significantly more compact when there are a lot of objects
smaller than the minimum kmalloc chunk size (32 bytes.)

This patch enables it for the Region and PhysicalPage classes.
In the PhysicalPage (8 bytes) case, it's a huge improvement since we
no longer waste 75% of the storage allocated.

There are also a number of ways this can be improved, so let's keep
working on it going forward.

1 files changed, 2 insertions, 0 deletions

diff --git a/Kernel/init.cpp b/Kernel/init.cpp
index f6a1da6c90..d73b1bca1d 100644
--- a/Kernel/init.cpp
+++ b/Kernel/init.cpp
@@ -29,6 +29,7 @@
 #include <Kernel/FileSystem/ProcFS.h>
 #include <Kernel/FileSystem/TmpFS.h>
 #include <Kernel/FileSystem/VirtualFileSystem.h>
+#include <Kernel/Heap/SlabAllocator.h>
 #include <Kernel/Heap/kmalloc.h>
 #include <Kernel/KParams.h>
 #include <Kernel/Multiboot.h>
@@ -187,6 +188,7 @@ extern "C" [[noreturn]] void init()
     sse_init();
 
     kmalloc_init();
+    slab_alloc_init();
     init_ksyms();
 
     // must come after kmalloc_init because we use AK_MAKE_ETERNAL in KParams