kmalloc: Add kmalloc_powerof2() and kmalloc_cachealign()

kmalloc_powerof2()
    Ensures that the returned address will be power of 2 aligned.

kmalloc_cachealign()
    Ensures that the returned address will be cacheline size aligned.
    It is useful to allocate structs declared with __cachealign
    attribute.

These two function probably should _not_ be used on the hot code path
due to the computational cost to find the nearest power of 2 size.

diff --git a/sys/kern/kern_slaballoc.c b/sys/kern/kern_slaballoc.c
index 9fc8a59..2f3a853 100644 (file)
--- a/sys/kern/kern_slaballoc.c
+++ b/sys/kern/kern_slaballoc.c
@@ -1566,3 +1566,21 @@ kmem_slab_free(void *ptr, vm_size_t size)
     crit_exit();
 }
 
+void *
+kmalloc_powerof2(unsigned long size_alloc, struct malloc_type *type, int flags)
+{
+       unsigned long size;
+
+       for (size = 1; size < size_alloc; size <<= 1)
+               ; /* EMPTY */
+       return kmalloc(size, type, flags);
+}
+
+void *
+kmalloc_cachealign(unsigned long size_alloc, struct malloc_type *type,
+    int flags)
+{
+       if (size_alloc < __VM_CACHELINE_SIZE)
+               size_alloc = __VM_CACHELINE_SIZE;
+       return kmalloc_powerof2(size_alloc, type, flags);
+}

diff --git a/sys/sys/malloc.h b/sys/sys/malloc.h
index 83b27e8..520bb64 100644 (file)
--- a/sys/sys/malloc.h
+++ b/sys/sys/malloc.h
@@ -204,6 +204,10 @@ char       *kstrdup (const char *, struct malloc_type *);
 #define kstrdup_debug(str, type, file, line)                   \
        kstrdup(str, type)
 #endif
+void   *kmalloc_powerof2 (unsigned long size, struct malloc_type *type,
+                          int flags);
+void   *kmalloc_cachealign (unsigned long size, struct malloc_type *type,
+                          int flags);
 void   kfree (void *addr, struct malloc_type *type);
 long   kmalloc_limit (struct malloc_type *type);