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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH] minios: add align support to _xmalloc()
Add align support to _xmalloc().
Signed-off-by: Samuel Thibault <samuel.thibault@xxxxxxxxxxxxx>
diff -r b13514ef6ec6 extras/mini-os/include/xmalloc.h
--- a/extras/mini-os/include/xmalloc.h Mon Jan 21 20:18:02 2008 +0000
+++ b/extras/mini-os/include/xmalloc.h Mon Jan 21 20:18:16 2008 +0000
@@ -7,7 +7,8 @@
/* Allocate space for array of typed objects. */
#define xmalloc_array(_type, _num) ((_type *)_xmalloc_array(sizeof(_type),
__alignof__(_type), _num))
-#define malloc(size) _xmalloc(size, 4)
+#define DEFAULT_ALIGN (sizeof(unsigned long))
+#define malloc(size) _xmalloc(size, DEFAULT_ALIGN)
#define free(ptr) xfree(ptr)
#define realloc(ptr, size) _realloc(ptr, size)
diff -r b13514ef6ec6 extras/mini-os/lib/xmalloc.c
--- a/extras/mini-os/lib/xmalloc.c Mon Jan 21 20:18:02 2008 +0000
+++ b/extras/mini-os/lib/xmalloc.c Mon Jan 21 20:18:16 2008 +0000
@@ -5,9 +5,11 @@
*
* File: xmaloc.c
* Author: Grzegorz Milos (gm281@xxxxxxxxx)
+ * Samuel Thibault (samuel.thibault@xxxxxxxxxxxxx)
* Changes:
*
* Date: Aug 2005
+ * Jan 2008
*
* Environment: Xen Minimal OS
* Description: simple memory allocator
@@ -39,22 +41,25 @@
#include <types.h>
#include <lib.h>
#include <list.h>
+#include <xmalloc.h>
static LIST_HEAD(freelist);
/* static spinlock_t freelist_lock = SPIN_LOCK_UNLOCKED; */
struct xmalloc_hdr
{
- /* Total including this hdr. */
+ /* Total including this hdr, unused padding and second hdr. */
size_t size;
struct list_head freelist;
-#if defined(__ia64__)
- // Needed for ia64 as long as the align parameter in _xmalloc()
- // is not supported.
- uint64_t pad;
-#endif
+} __cacheline_aligned;
-} __cacheline_aligned;
+/* Unused padding data between the two hdrs. */
+
+struct xmalloc_pad
+{
+ /* Size including both hdrs. */
+ size_t hdr_size;
+};
static void maybe_split(struct xmalloc_hdr *hdr, size_t size, size_t block)
{
@@ -62,11 +67,13 @@ static void maybe_split(struct xmalloc_h
size_t leftover = block - size;
/* If enough is left to make a block, put it on free list. */
- if ( leftover >= (2 * sizeof(struct xmalloc_hdr)) )
+ if ( leftover >= (2 * (sizeof(struct xmalloc_hdr) + sizeof(struct
xmalloc_pad))) )
{
extra = (struct xmalloc_hdr *)((unsigned long)hdr + size);
extra->size = leftover;
+ /* spin_lock_irqsave(&freelist_lock, flags); */
list_add(&extra->freelist, &freelist);
+ /* spin_unlock_irqrestore(&freelist_lock, flags); */
}
else
{
@@ -78,7 +85,7 @@ static void maybe_split(struct xmalloc_h
hdr->freelist.next = hdr->freelist.prev = NULL;
}
-static void *xmalloc_new_page(size_t size)
+static struct xmalloc_hdr *xmalloc_new_page(size_t size)
{
struct xmalloc_hdr *hdr;
/* unsigned long flags; */
@@ -87,18 +94,30 @@ static void *xmalloc_new_page(size_t siz
if ( hdr == NULL )
return NULL;
- /* spin_lock_irqsave(&freelist_lock, flags); */
maybe_split(hdr, size, PAGE_SIZE);
- /* spin_unlock_irqrestore(&freelist_lock, flags); */
- return hdr+1;
+ return hdr;
+}
+
+/* Return size, increased to alignment with align. */
+static inline size_t align_up(size_t size, size_t align)
+{
+ return (size + align - 1) & ~(align - 1);
}
/* Big object? Just use the page allocator. */
-static void *xmalloc_whole_pages(size_t size)
+static void *xmalloc_whole_pages(size_t size, size_t align)
{
struct xmalloc_hdr *hdr;
- unsigned int pageorder = get_order(size);
+ struct xmalloc_pad *pad;
+ unsigned int pageorder;
+ void *ret;
+ /* Room for headers */
+ size_t hdr_size = sizeof(struct xmalloc_hdr) + sizeof(struct xmalloc_pad);
+ /* Align for actual beginning of data */
+ hdr_size = align_up(hdr_size, align);
+
+ pageorder = get_order(hdr_size + size);
hdr = (struct xmalloc_hdr *)alloc_pages(pageorder);
if ( hdr == NULL )
@@ -108,54 +127,82 @@ static void *xmalloc_whole_pages(size_t
/* Debugging aid. */
hdr->freelist.next = hdr->freelist.prev = NULL;
- return hdr+1;
-}
-
-/* Return size, increased to alignment with align. */
-static inline size_t align_up(size_t size, size_t align)
-{
- return (size + align - 1) & ~(align - 1);
+ ret = (char*)hdr + hdr_size;
+ pad = (struct xmalloc_pad *) ret - 1;
+ pad->hdr_size = hdr_size;
+ return ret;
}
void *_xmalloc(size_t size, size_t align)
{
- struct xmalloc_hdr *i;
+ struct xmalloc_hdr *i, *hdr = NULL;
+ uintptr_t data_begin;
+ size_t hdr_size;
/* unsigned long flags; */
- /* Add room for header, pad to align next header. */
- size += sizeof(struct xmalloc_hdr);
- size = align_up(size, __alignof__(struct xmalloc_hdr));
+ hdr_size = sizeof(struct xmalloc_hdr) + sizeof(struct xmalloc_pad);
+ /* Align on headers requirements. */
+ align = align_up(align, __alignof__(struct xmalloc_hdr));
+ align = align_up(align, __alignof__(struct xmalloc_pad));
/* For big allocs, give them whole pages. */
- if ( size >= PAGE_SIZE )
- return xmalloc_whole_pages(size);
+ if ( size + align_up(hdr_size, align) >= PAGE_SIZE )
+ return xmalloc_whole_pages(size, align);
/* Search free list. */
/* spin_lock_irqsave(&freelist_lock, flags); */
list_for_each_entry( i, &freelist, freelist )
{
- if ( i->size < size )
+ data_begin = align_up((uintptr_t)i + hdr_size, align);
+
+ if ( data_begin + size > (uintptr_t)i + i->size )
continue;
+
list_del(&i->freelist);
- maybe_split(i, size, i->size);
/* spin_unlock_irqrestore(&freelist_lock, flags); */
- return i+1;
+
+ uintptr_t size_before = (data_begin - hdr_size) - (uintptr_t)i;
+
+ if (size_before >= 2 * hdr_size) {
+ /* Worth splitting the beginning */
+ struct xmalloc_hdr *new_i = (void*)(data_begin - hdr_size);
+ new_i->size = i->size - size_before;
+ i->size = size_before;
+ /* spin_lock_irqsave(&freelist_lock, flags); */
+ list_add(&i->freelist, &freelist);
+ /* spin_unlock_irqrestore(&freelist_lock, flags); */
+ i = new_i;
+ }
+ maybe_split(i, (data_begin + size) - (uintptr_t)i, i->size);
+ hdr = i;
+ break;
}
- /* spin_unlock_irqrestore(&freelist_lock, flags); */
- /* Alloc a new page and return from that. */
- return xmalloc_new_page(size);
+ if (!hdr) {
+ /* spin_unlock_irqrestore(&freelist_lock, flags); */
+
+ /* Alloc a new page and return from that. */
+ hdr = xmalloc_new_page(align_up(hdr_size, align) + size);
+ data_begin = (uintptr_t)hdr + align_up(hdr_size, align);
+ }
+
+ struct xmalloc_pad *pad = (struct xmalloc_pad *) data_begin - 1;
+ pad->hdr_size = data_begin - (uintptr_t)hdr;
+ BUG_ON(data_begin % align);
+ return (void*)data_begin;
}
void xfree(const void *p)
{
/* unsigned long flags; */
struct xmalloc_hdr *i, *tmp, *hdr;
+ struct xmalloc_pad *pad;
if ( p == NULL )
return;
- hdr = (struct xmalloc_hdr *)p - 1;
+ pad = (struct xmalloc_pad *)p - 1;
+ hdr = (struct xmalloc_hdr *)((char *)p - pad->hdr_size);
/* We know hdr will be on same page. */
if(((long)p & PAGE_MASK) != ((long)hdr & PAGE_MASK))
@@ -227,15 +274,19 @@ void *_realloc(void *ptr, size_t size)
{
void *new;
struct xmalloc_hdr *hdr;
+ struct xmalloc_pad *pad;
if (ptr == NULL)
- return _xmalloc(size, 4);
+ return _xmalloc(size, DEFAULT_ALIGN);
- hdr = (struct xmalloc_hdr *)ptr - 1;
- if (hdr->size >= size)
+ pad = (struct xmalloc_pad *)ptr - 1;
+ hdr = (struct xmalloc_hdr *)((char*)ptr - pad->hdr_size);
+ if (hdr->size >= size) {
+ maybe_split(hdr, size, hdr->size);
return ptr;
+ }
- new = _xmalloc(size, 4);
+ new = _xmalloc(size, DEFAULT_ALIGN);
if (new == NULL)
return NULL;
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