Re: [PATCH] dynamic cache allocation

[phcoder <phcoder@gmail.com>]

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Update to the patch
phcoder wrote:
> Vesa Jääskeläinen wrote:
>> phcoder wrote:
>>> Hello. Discussing with Robert Millan and Bean on IRC we noticed that
>>> disk cache index is statically allocated. Here is a proposal to change
>>> it to dynamic allocation proportional to the size of available memory.
>>
>> And the gain is ?
> 
> Faster booting if extensive directory scanning is needed to load OS 
> (applies to xnu)
>>
>>
>> _______________________________________________
>> Grub-devel mailing list
>> Grub-devel@gnu.org
>> http://lists.gnu.org/mailman/listinfo/grub-devel
> 
> 


-- 

Regards
Vladimir 'phcoder' Serbinenko

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Index: kern/disk.c
===================================================================
--- kern/disk.c	(revision 2021)
+++ kern/disk.c	(working copy)
@@ -41,7 +41,8 @@ struct grub_disk_cache
   int lock;
 };
 
-static struct grub_disk_cache grub_disk_cache_table[GRUB_DISK_CACHE_NUM];
+static struct grub_disk_cache *grub_disk_cache_table = 0;
+static int grub_disk_cache_num = 0;
 
 void (*grub_disk_firmware_fini) (void);
 int grub_disk_firmware_is_tainted;
@@ -68,7 +69,7 @@ grub_disk_cache_get_index (unsigned long dev_id, u
 {
   return ((dev_id * 524287UL + disk_id * 2606459UL
 	   + ((unsigned) (sector >> GRUB_DISK_CACHE_BITS)))
-	  % GRUB_DISK_CACHE_NUM);
+	  % grub_disk_cache_num);
 }
 
 static void
@@ -78,6 +79,9 @@ grub_disk_cache_invalidate (unsigned long dev_id,
   unsigned index;
   struct grub_disk_cache *cache;
 
+  if (!grub_disk_cache_table)
+    return;
+
   sector &= ~(GRUB_DISK_CACHE_SIZE - 1);
   index = grub_disk_cache_get_index (dev_id, disk_id, sector);
   cache = grub_disk_cache_table + index;
@@ -97,7 +101,10 @@ grub_disk_cache_invalidate_all (void)
 {
   unsigned i;
 
-  for (i = 0; i < GRUB_DISK_CACHE_NUM; i++)
+  if (!grub_disk_cache_table)
+    return;
+
+  for (i = 0; i < grub_disk_cache_num; i++)
     {
       struct grub_disk_cache *cache = grub_disk_cache_table + i;
 
@@ -116,6 +123,14 @@ grub_disk_cache_fetch (unsigned long dev_id, unsig
   struct grub_disk_cache *cache;
   unsigned index;
 
+  if (!grub_disk_cache_table)
+    {
+#if 0
+      grub_disk_cache_misses++;
+#endif
+      return 0;
+    }
+
   index = grub_disk_cache_get_index (dev_id, disk_id, sector);
   cache = grub_disk_cache_table + index;
 
@@ -143,6 +158,9 @@ grub_disk_cache_unlock (unsigned long dev_id, unsi
   struct grub_disk_cache *cache;
   unsigned index;
 
+  if (!grub_disk_cache_table)
+    return ;
+
   index = grub_disk_cache_get_index (dev_id, disk_id, sector);
   cache = grub_disk_cache_table + index;
 
@@ -157,7 +175,24 @@ grub_disk_cache_store (unsigned long dev_id, unsig
 {
   unsigned index;
   struct grub_disk_cache *cache;
-  
+
+  if (!grub_disk_cache_table)
+    {
+#ifdef GRUB_UTIL
+      grub_disk_cache_num = GRUB_UTIL_CACHE_NUM;
+#else
+      grub_disk_cache_num = grub_mm_get_free ()  / GRUB_DISK_CACHE_DIVIDE;
+#endif
+      grub_disk_cache_table = (struct grub_disk_cache *)
+	grub_malloc (grub_disk_cache_num * sizeof (struct grub_disk_cache));
+      grub_memset (grub_disk_cache_table, 0,
+		   grub_disk_cache_num * sizeof (struct grub_disk_cache));
+    }
+
+  if (!grub_disk_cache_table)
+    return grub_error (GRUB_ERR_OUT_OF_MEMORY, 
+		       "couldn't allocate space for cache index");
+
   grub_disk_cache_invalidate (dev_id, disk_id, sector);
   
   index = grub_disk_cache_get_index (dev_id, disk_id, sector);
Index: kern/mm.c
===================================================================
--- kern/mm.c	(revision 2021)
+++ kern/mm.c	(working copy)
@@ -449,6 +449,33 @@ grub_realloc (void *ptr, grub_size_t size)
   return q;
 }
 
+grub_size_t
+grub_mm_get_free (void)
+{
+  grub_mm_region_t r;
+  grub_size_t ret = 0;
+
+  for (r = base; r; r = r->next)
+    {
+      grub_mm_header_t p;
+
+      /* Follow the free list.  */
+      p = r->first;
+      do
+	{
+	  if (p->magic != GRUB_MM_FREE_MAGIC)
+	    grub_fatal ("free magic is broken at %p: 0x%x", p, p->magic);
+
+	  ret += p->size << GRUB_MM_ALIGN_LOG2;
+	  p = p->next;
+	}
+      while (p != r->first);
+    }
+
+  return ret;
+}
+
+
 #ifdef MM_DEBUG
 int grub_mm_debug = 0;
 
Index: include/grub/disk.h
===================================================================
--- include/grub/disk.h	(revision 2021)
+++ include/grub/disk.h	(working copy)
@@ -129,9 +129,14 @@ typedef struct grub_disk_memberlist *grub_disk_mem
 #define GRUB_DISK_SECTOR_SIZE	0x200
 #define GRUB_DISK_SECTOR_BITS	9
 
-/* The maximum number of disk caches.  */
-#define GRUB_DISK_CACHE_NUM	1021
+/* Allocate one cache entry per N bytes. 
+   By default use up to one quarter of memory available for allocation  */
+#define GRUB_DISK_CACHE_DIVIDE	16536
 
+/* On grub-util we can't know the available memory size and since host OS 
+   already caches data we don't need a big cache*/
+#define GRUB_UTIL_CACHE_NUM 100
+
 /* The size of a disk cache in sector units.  */
 #define GRUB_DISK_CACHE_SIZE	8
 #define GRUB_DISK_CACHE_BITS	3
Index: include/grub/mm.h
===================================================================
--- include/grub/mm.h	(revision 2021)
+++ include/grub/mm.h	(working copy)
@@ -33,6 +33,7 @@ void *EXPORT_FUNC(grub_malloc) (grub_size_t size);
 void EXPORT_FUNC(grub_free) (void *ptr);
 void *EXPORT_FUNC(grub_realloc) (void *ptr, grub_size_t size);
 void *EXPORT_FUNC(grub_memalign) (grub_size_t align, grub_size_t size);
+grub_size_t EXPORT_FUNC(grub_mm_get_free) (void);
 
 /* For debugging.  */
 #if defined(MM_DEBUG) && !defined(GRUB_UTIL)
Index: ChangeLog
===================================================================
--- ChangeLog	(revision 2021)
+++ ChangeLog	(working copy)
@@ -1,3 +1,17 @@
+2009-03-07  Vladimir Serbinenko  <phcoder@gmail.com>
+
+	Dynamic cache allocation
+
+	* kern/disk.c (grub_disk_cache_table): changed declaration as pointer 
+	instead of array. All users updated
+	* include/grub/disk.h (GRUB_DISK_CACHE_NUM): changed to ...
+	(grub_disk_cache_num): ... a variable. All users updated
+	* kern/disk.c (grub_disk_cache_store): allocate cache index
+	* kern/mm.c (grub_mm_get_free): new function
+	* include/grub/disk.h (GRUB_DISK_CACHE_DIVIDE): new declaration
+	(GRUB_UTIL_CACHE_NUM): likewise
+	* include/grub/mm.h (grub_mm_get_free): likewise
+
 2009-03-07  Bean  <bean123ch@gmail.com>
 
 	* loader/i386/efi/linux.c (grub_rescue_cmd_initrd): Fix a bug in initrd