jeyzu pushed a commit to branch master.
commit 00af0e77e327d8ca8e1d78caaf0cfdd1251c0fd2
Author: Jérémy Zurcher <[email protected]>
Date: Thu May 16 11:46:20 2013 +0200
eo ptr ind: minimize amount of wasted memory
- because of mmap PAGE_SIZE alignement and added magic header, almost a
memory page is wasted per table and mid table allocation.
- reducing the number of tables per mid table and the number of entries
per table solves this.
---
src/lib/eo/eo_ptr_indirection.c | 16 +++++++++++-----
1 file changed, 11 insertions(+), 5 deletions(-)
diff --git a/src/lib/eo/eo_ptr_indirection.c b/src/lib/eo/eo_ptr_indirection.c
index 47c5295..b355370 100644
--- a/src/lib/eo/eo_ptr_indirection.c
+++ b/src/lib/eo/eo_ptr_indirection.c
@@ -68,6 +68,8 @@
# define BITS_TABLE_ID 5
# define BITS_ENTRY_ID 12
# define BITS_GENERATION_COUNTER 10
+# define DROPPED_TABLES 0
+# define DROPPED_ENTRIES 3
typedef int16_t Table_Index;
typedef uint16_t Generation_Counter;
#else
@@ -76,6 +78,8 @@ typedef uint16_t Generation_Counter;
# define BITS_TABLE_ID 11
# define BITS_ENTRY_ID 12
# define BITS_GENERATION_COUNTER 30
+# define DROPPED_TABLES 2
+# define DROPPED_ENTRIES 2
typedef int16_t Table_Index;
typedef uint32_t Generation_Counter;
#endif
@@ -86,16 +90,17 @@ typedef uint32_t Generation_Counter;
#define SHIFT_TABLE_ID (BITS_ENTRY_ID + BITS_GENERATION_COUNTER)
#define SHIFT_ENTRY_ID (BITS_GENERATION_COUNTER)
-/* Maximum ranges */
+/* Maximum ranges - a few tables and entries are dropped to minimize the amount
+ * of wasted bytes, see _eo_id_mem_alloc */
#define MAX_MID_TABLE_ID (1 << BITS_MID_TABLE_ID)
-#define MAX_TABLE_ID (1 << BITS_TABLE_ID)
-#define MAX_ENTRY_ID (1 << BITS_ENTRY_ID)
+#define MAX_TABLE_ID ((1 << BITS_TABLE_ID) - DROPPED_TABLES )
+#define MAX_ENTRY_ID ((1 << BITS_ENTRY_ID) - DROPPED_ENTRIES)
#define MAX_GENERATIONS (1 << BITS_GENERATION_COUNTER)
/* Masks */
#define MASK_MID_TABLE_ID (MAX_MID_TABLE_ID - 1)
-#define MASK_TABLE_ID (MAX_TABLE_ID - 1)
-#define MASK_ENTRY_ID (MAX_ENTRY_ID - 1)
+#define MASK_TABLE_ID ((1 << BITS_TABLE_ID) - 1)
+#define MASK_ENTRY_ID ((1 << BITS_ENTRY_ID) - 1)
#define MASK_GENERATIONS (MAX_GENERATIONS - 1)
#define MEM_HEADER_SIZE 16
@@ -127,6 +132,7 @@ _eo_id_mem_alloc(size_t size)
hdr = ptr;
hdr->size = newsize;
hdr->magic = MEM_MAGIC;
+ /* DBG("asked:%lu allocated:%lu wasted:%lu bytes", size, newsize, (newsize
- size)); */
return (void *)(((unsigned char *)ptr) + MEM_HEADER_SIZE);
#else
return malloc(size);
--
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