[PATCH] kmem_find_general_cachep to static inline

[PATCH] kmem_find_general_cachep to static inline

[Matthew M]

Hi all,

Inlined patch against 2.5.1-pre5 moves kmem_find_general_cachep and the 
cache_sizes struct to slab.h and declares it static inline, prompted by a 
comment in the source. Compiles and runs fine here.

First patch, please explain what I did wrong :)

*MatthewM*

-- 
<Addi> Alter.net seems to have replaced one of its router with a zucchini.
--

--- ./include/linux/slab.h~	Mon Dec  3 20:23:27 2001
+++ ./include/linux/slab.h	Mon Dec  3 20:26:01 2001
@@ -45,6 +45,44 @@
 #define SLAB_CTOR_ATOMIC	0x002UL		/* tell constructor it can't sleep */
 #define	SLAB_CTOR_VERIFY	0x004UL		/* tell constructor it's a verify call */

+/* Size description struct for general caches. */
+typedef struct cache_sizes {
+	size_t		 cs_size;
+	kmem_cache_t	*cs_cachep;
+	kmem_cache_t	*cs_dmacachep;
+} cache_sizes_t;
+
+static cache_sizes_t cache_sizes[] = {
+#if PAGE_SIZE == 4096
+	{    32,	NULL, NULL},
+#endif
+	{    64,	NULL, NULL},
+	{   128,	NULL, NULL},
+	{   256,	NULL, NULL},
+	{   512,	NULL, NULL},
+	{  1024,	NULL, NULL},
+	{  2048,	NULL, NULL},
+	{  4096,	NULL, NULL},
+	{  8192,	NULL, NULL},
+	{ 16384,	NULL, NULL},
+	{ 32768,	NULL, NULL},
+	{ 65536,	NULL, NULL},
+	{131072,	NULL, NULL},
+	{     0,	NULL, NULL}
+};
+
+static inline kmem_cache_t * kmem_find_general_cachep (size_t size, int 
gfpflags)
+{
+	cache_sizes_t *csizep = cache_sizes;
+
+	for ( ; csizep->cs_size; csizep++) {
+		if (size > csizep->cs_size)
+			continue;
+		break;
+	}
+	return (gfpflags & GFP_DMA) ? csizep->cs_dmacachep : csizep->cs_cachep;
+}
+
 /* prototypes */
 extern void kmem_cache_init(void);
 extern void kmem_cache_sizes_init(void);
--- ./mm/slab.c~	Tue Dec  4 18:12:45 2001
+++ ./mm/slab.c	Tue Dec  4 18:12:50 2001
@@ -326,32 +326,6 @@
 #define	SET_PAGE_SLAB(pg,x)   ((pg)->list.prev = (struct list_head *)(x))
 #define	GET_PAGE_SLAB(pg)     ((slab_t *)(pg)->list.prev)
 
-/* Size description struct for general caches. */
-typedef struct cache_sizes {
-	size_t		 cs_size;
-	kmem_cache_t	*cs_cachep;
-	kmem_cache_t	*cs_dmacachep;
-} cache_sizes_t;
-
-static cache_sizes_t cache_sizes[] = {
-#if PAGE_SIZE == 4096
-	{    32,	NULL, NULL},
-#endif
-	{    64,	NULL, NULL},
-	{   128,	NULL, NULL},
-	{   256,	NULL, NULL},
-	{   512,	NULL, NULL},
-	{  1024,	NULL, NULL},
-	{  2048,	NULL, NULL},
-	{  4096,	NULL, NULL},
-	{  8192,	NULL, NULL},
-	{ 16384,	NULL, NULL},
-	{ 32768,	NULL, NULL},
-	{ 65536,	NULL, NULL},
-	{131072,	NULL, NULL},
-	{     0,	NULL, NULL}
-};
-
 /* internal cache of cache description objs */
 static kmem_cache_t cache_cache = {
 	slabs_full:	LIST_HEAD_INIT(cache_cache.slabs_full),
@@ -1587,22 +1561,6 @@
 	c = GET_PAGE_CACHE(virt_to_page(objp));
 	__kmem_cache_free(c, (void*)objp);
 	local_irq_restore(flags);
-}
-
-kmem_cache_t * kmem_find_general_cachep (size_t size, int gfpflags)
-{
-	cache_sizes_t *csizep = cache_sizes;
-
-	/* This function could be moved to the header file, and
-	 * made inline so consumers can quickly determine what
-	 * cache pointer they require.
-	 */
-	for ( ; csizep->cs_size; csizep++) {
-		if (size > csizep->cs_size)
-			continue;
-		break;
-	}
-	return (gfpflags & GFP_DMA) ? csizep->cs_dmacachep : csizep->cs_cachep;
 }

 #ifdef CONFIG_SMP

Re: [PATCH] kmem_find_general_cachep to static inline

[Bernd Eckenfels]

In article <m16BKdv-000CgdC@Wasteland> you wrote:
> First patch, please explain what I did wrong :)

Nothing, but can be improved further.

One can use that function in kmalloc() and then optimize the function using
a binary search.

--- slab.c	2001/09/21 16:28:50	1.27
+++ slab.c	2001/12/05 07:51:58
@@ -1533,14 +1533,13 @@
  */
 void * kmalloc (size_t size, int flags)
 {
-	cache_sizes_t *csizep = cache_sizes;
+	kmem_cache_t *cp;
+	
+	cp = kmem_find_general_cachep(size, flags);
+	
+	if (cp)
+		return __kmem_cache_alloc(cp, flags);
 
-	for (; csizep->cs_size; csizep++) {
-		if (size > csizep->cs_size)
-			continue;
-		return __kmem_cache_alloc(flags & GFP_DMA ?
-			 csizep->cs_dmacachep : csizep->cs_cachep, flags);
-	}
 	return NULL;
 }


the patch for having the binary search will look something like:

From: Momchil Velikov <velco@fadata.bg>

@@ -1589,18 +1583,66 @@ void kfree (const void *objp)
 
 kmem_cache_t * kmem_find_general_cachep (size_t size, int gfpflags)
 {
-	cache_sizes_t *csizep = cache_sizes;
+	int idx;
 
-	/* This function could be moved to the header file, and
-	 * made inline so consumers can quickly determine what
-	 * cache pointer they require.
-	 */
-	for ( ; csizep->cs_size; csizep++) {
-		if (size > csizep->cs_size)
-			continue;
+	switch (size) {
+#if PAGE_SIZE == 4096
+	case 0 ... 32: 
+		idx = 0;
+		break;
+	case 33 ... 64:
+		idx = 1;
+		break;
+#else
+	case 0 ... 64:
+		idx = 1;
+		break;
+#endif
+	case 65 ... 128:
+		idx = 2;
+		break;
+	case 129 ... 256:
+		idx = 3;
+		break;
+	case 257 ...512:
+		idx = 4;
+		break;
+	case 513 ... 1024:
+		idx = 5;
+		break;
+	case 1025 ... 2048:
+		idx = 6;
+		break;
+	case 2049 ... 4096:
+		idx = 7;
+		break;
+	case 4097 ... 8192:
+		idx = 8;
+		break;
+	case 8193 ... 16384:
+		idx = 9;
+		break;
+	case 16385 ... 32768:
+		idx = 10;
+		break;
+	case 32769 ... 65536:
+		idx = 11;
+		break;
+	case 65537 ... 131072:
+		idx = 12;
+		break;
+	default:
+		idx = -1;
 		break;
 	}
-	return (gfpflags & GFP_DMA) ? csizep->cs_dmacachep : csizep->cs_cachep;
+
+	if (idx == -1)
+		return NULL;
+
+#if PAGE_SIZE != 4096
+	idx = idx - 1;
+#endif
+	return (gfpflags & GFP_DMA) ? cache_sizes [idx].cs_dmacachep : cache_sizes [idx].cs_cachep;
 }
 
 #ifdef CONFIG_SMP


I have not tested yet if the "idx -1" is optimized good, or if it is better
to have assigend idx the values depending on the #define. But otherwise it
should work well.

Greetings
Bernd