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Fixes and improvements in mmgr.c

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Bug fixes in page allocator
Significant performance improvements
This commit is contained in:
ngiddings
2022-11-20 16:32:25 -06:00
parent ccc35bc4c2
commit 590290f92b
1 changed files with 78 additions and 36 deletions
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94
src/mmgr.c
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@@ -6,6 +6,8 @@
#include <stdint.h>
#include <stdbool.h>
#define MAX_CACHE_SIZE 32
struct page_map_t
{
/**
@@ -15,6 +17,12 @@ struct page_map_t
*/
unsigned long *bitmap;
/**
* @brief Stores a list of available blocks of memory to speed up allocation.
*
*/
unsigned long *cache;
/**
* @brief The size of the bitmap in bytes.
*
@@ -50,60 +58,77 @@ const int bitmap_word_size = 8 * sizeof(*page_map.bitmap);
int split_block(int index)
{
if(index)
if (index)
{
int bitmap_index = index / bitmap_word_size;
int bitmap_offset = index % bitmap_word_size;
page_map.bitmap[bitmap_index] &= ~(1 << bitmap_offset);
unsigned long bitmap_index = index / bitmap_word_size;
unsigned long bitmap_offset = index % bitmap_word_size;
page_map.bitmap[bitmap_index] &= ~((unsigned long)1 << bitmap_offset);
index *= 2;
bitmap_index = index / bitmap_word_size;
bitmap_offset = index / bitmap_word_size;
page_map.bitmap[bitmap_index] |= 1 << bitmap_offset;
page_map.bitmap[bitmap_index] |= 1 << (bitmap_offset ^ 1);
bitmap_offset = index % bitmap_word_size;
page_map.bitmap[bitmap_index] |= (unsigned long)1 << bitmap_offset;
page_map.bitmap[bitmap_index] |= (unsigned long)1 << (bitmap_offset ^ 1);
unsigned long depth = llog2(index + 1) - 1;
unsigned long cache_start = llog2(bitmap_word_size);
if(depth >= cache_start && page_map.cache[depth - cache_start] == 0)
{
page_map.cache[depth - cache_start] = index + 1;
}
}
return index;
}
int find_free_region(int height)
{
if(height > page_map.height || height < 0)
if (height > page_map.height || height < 0)
{
return 0;
}
else if(height <= page_map.height - ilog2(bitmap_word_size))
else if (height <= page_map.height - ilog2(bitmap_word_size))
{
for(int index = (1 << (page_map.height - height)) / bitmap_word_size;
index < (1 << (page_map.height - height + 1)) / bitmap_word_size;
index++)
if(page_map.cache[page_map.height - height - llog2(bitmap_word_size)])
{
if(page_map.bitmap[index] != 0)
unsigned long index = page_map.cache[page_map.height - height - llog2(bitmap_word_size)];
page_map.cache[page_map.height - height - llog2(bitmap_word_size)] = 0;
return index;
}
unsigned long start = (1 << (page_map.height - height)) / bitmap_word_size;
unsigned long end = ((1 << (page_map.height - height + 1)) / bitmap_word_size);
for (int index = start; index < end; index++)
{
if (page_map.bitmap[index] != 0)
{
return bitmap_word_size * index + __builtin_ctz(page_map.bitmap[index]);
return bitmap_word_size * index + __builtin_ctzl(page_map.bitmap[index]);
}
}
}
else
{
static const int bitmasks[] = {0x00000002, 0x0000000C, 0x000000F0, 0x0000FF00, 0xFFFF0000};
#if __SIZEOF_LONG__ == 8
static const unsigned long bitmasks[] = {0x00000002, 0x0000000C, 0x000000F0, 0x0000FF00, 0xFFFF0000, 0xFFFFFFFF00000000};
#else
static const unsigned long bitmasks[] = {0x00000002, 0x0000000C, 0x000000F0, 0x0000FF00, 0xFFFF0000};
#endif
int depth = page_map.height - height;
if(page_map.bitmap[0] & bitmasks[depth])
if (page_map.bitmap[0] & bitmasks[depth])
{
return __builtin_ctz(page_map.bitmap[0] & bitmasks[depth]);
return __builtin_ctzl(page_map.bitmap[0] & bitmasks[depth]);
}
}
return split_block(find_free_region(height + 1));
}
physaddr_t reserve_region(size_t size)
{
int height = llog2(size / page_map.block_size);
int index = find_free_region(height);
if(index)
if (index)
{
int bitmap_index = index / bitmap_word_size;
int bitmap_offset = index % bitmap_word_size;
page_map.bitmap[bitmap_index] &= ~(1 << bitmap_offset);
return (page_map.block_size << height) * (index - (1 << (page_map.height - height)));
page_map.bitmap[bitmap_index] &= ~((unsigned long)1 << bitmap_offset);
return (page_map.block_size << height) * (index - ((unsigned long)1 << (page_map.height - height)));
}
else
{
@@ -114,18 +139,29 @@ physaddr_t reserve_region(size_t size)
int free_region(physaddr_t location, size_t size)
{
int height = llog2(size / page_map.block_size);
int index = (location / (page_map.block_size * (1 << height))) + (1 << (page_map.height - height));
int index = (location / (page_map.block_size * ((unsigned long)1 << height))) + (1 << (page_map.height - height));
int bitmap_index = index / bitmap_word_size;
int bitmap_offset = index % bitmap_word_size;
page_map.bitmap[bitmap_index] |= 1 << bitmap_offset;
while(page_map.bitmap[bitmap_index] & (1 << (bitmap_offset ^ 1)))
page_map.bitmap[bitmap_index] |= (unsigned long)1 << bitmap_offset;
unsigned long cache_start = llog2(bitmap_word_size);
while (page_map.bitmap[bitmap_index] & ((unsigned long)1 << (bitmap_offset ^ 1)))
{
page_map.bitmap[bitmap_index] &= ~(1 << bitmap_offset);
page_map.bitmap[bitmap_index] &= ~(1 << (bitmap_offset ^ 1));
unsigned long depth = llog2(index + 1) - 1;
if(page_map.cache[depth - cache_start] == (index ^ 1))
{
page_map.cache[depth - cache_start] = ENOMEM;
}
page_map.bitmap[bitmap_index] &= ~((unsigned long)1 << bitmap_offset);
page_map.bitmap[bitmap_index] &= ~((unsigned long)1 << (bitmap_offset ^ 1));
index /= 2;
bitmap_index = index / bitmap_word_size;
bitmap_offset = index % bitmap_word_size;
page_map.bitmap[bitmap_index] |= 1 << bitmap_offset;
page_map.bitmap[bitmap_index] |= (unsigned long)1 << bitmap_offset;
}
unsigned long depth = llog2(index + 1) - 1;
if (depth >= cache_start && page_map.cache[depth - cache_start] == 0)
{
page_map.cache[depth - cache_start] = index;
}
return ENONE;
}
@@ -157,9 +193,11 @@ void *page_map_end()
enum error_t initialize_page_map(struct memory_map_t *map, void *base, size_t memory_size, unsigned long block_size)
{
static unsigned long page_map_cache[MAX_CACHE_SIZE];
// Round memory_size up to nearest power of 2
memory_size = 1 << llog2(memory_size);
page_map.bitmap = (unsigned long*) base;
page_map.cache = page_map_cache;
page_map.bitmap_size = (memory_size / page_size) / 4;
page_map.block_size = block_size;
page_map.height = llog2(memory_size / block_size);
@@ -229,6 +267,10 @@ enum error_t initialize_page_map(struct memory_map_t *map, void *base, size_t me
location += chunk_size;
}
}
for(int i = 0; i < MAX_CACHE_SIZE; i++)
{
page_map.cache[i] = 0;
}
return ENONE;
}