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talloc: use a struct for pool headers.

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This neatens the code a bit (we should do a similar thing for all the
TALLOC_CHUNK macros).

Two subtler changes:
(1) As a result of the struct, we actually pack object_count into the 
    talloc header on 32-bit platforms (since the header is 40 bytes, but
    needs to be 16-byte aligned).
(2) I avoid VALGRIND_MAKE_MEM_UNDEFINED on memmove when we resize the
    only entry in a pool; that's done later anyway.

With -O2 on my 11.04 Ubuntu 32-bit x86 laptop, the talloc_pool speed as
measured by testsuite.c actually increases 10%.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
Rusty Russell 2012-07-18 04:53:31 +09:30
parent d1a5a5bc80
commit 8893215aaf
2 changed files with 90 additions and 106 deletions
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194
lib/talloc/talloc.c
View File

@ -437,49 +437,50 @@ _PUBLIC_ const char *talloc_parent_name(const void *ptr)
memory footprint of each talloc chunk by those 16 bytes.
*/
#define TALLOC_POOL_HDR_SIZE 16
union talloc_pool_chunk {
/* This lets object_count nestle into 16-byte padding of talloc_chunk,
* on 32-bit platforms. */
struct tc_pool_hdr {
struct talloc_chunk c;
unsigned int object_count;
} hdr;
/* This makes it always 16 byte aligned. */
char pad[TC_ALIGN16(sizeof(struct tc_pool_hdr))];
};
#define TC_POOL_SPACE_LEFT(_pool_tc) \
PTR_DIFF(TC_HDR_SIZE + (_pool_tc)->size + (char *)(_pool_tc), \
(_pool_tc)->pool)
static void *tc_pool_end(union talloc_pool_chunk *pool_tc)
{
return (char *)pool_tc + TC_HDR_SIZE + pool_tc->hdr.c.size;
}
#define TC_POOL_FIRST_CHUNK(_pool_tc) \
((void *)(TC_HDR_SIZE + TALLOC_POOL_HDR_SIZE + (char *)(_pool_tc)))
static size_t tc_pool_space_left(union talloc_pool_chunk *pool_tc)
{
return (char *)tc_pool_end(pool_tc) - (char *)pool_tc->hdr.c.pool;
}
#define TC_POOLMEM_CHUNK_SIZE(_tc) \
TC_ALIGN16(TC_HDR_SIZE + (_tc)->size)
static void *tc_pool_first_chunk(union talloc_pool_chunk *pool_tc)
{
return pool_tc + 1;
}
#define TC_POOLMEM_NEXT_CHUNK(_tc) \
((void *)(TC_POOLMEM_CHUNK_SIZE(tc) + (char*)(_tc)))
/* If tc is inside a pool, this gives the next neighbour. */
static void *tc_next_chunk(struct talloc_chunk *tc)
{
return (char *)tc + TC_ALIGN16(TC_HDR_SIZE + tc->size);
}
/* Mark the whole remaining pool as not accessable */
#define TC_INVALIDATE_FILL_POOL(_pool_tc) do { \
if (unlikely(talloc_fill.enabled)) { \
size_t _flen = TC_POOL_SPACE_LEFT(_pool_tc); \
char *_fptr = (char *)(_pool_tc)->pool; \
memset(_fptr, talloc_fill.fill_value, _flen); \
} \
} while(0)
static void tc_invalidate_pool(union talloc_pool_chunk *pool_tc)
{
size_t flen = tc_pool_space_left(pool_tc);
if (unlikely(talloc_fill.enabled)) {
memset(pool_tc->hdr.c.pool, talloc_fill.fill_value, flen);
}
#if defined(DEVELOPER) && defined(VALGRIND_MAKE_MEM_NOACCESS)
/* Mark the whole remaining pool as not accessable */
#define TC_INVALIDATE_VALGRIND_POOL(_pool_tc) do { \
size_t _flen = TC_POOL_SPACE_LEFT(_pool_tc); \
char *_fptr = (char *)(_pool_tc)->pool; \
VALGRIND_MAKE_MEM_NOACCESS(_fptr, _flen); \
} while(0)
#else
#define TC_INVALIDATE_VALGRIND_POOL(_pool_tc) do { } while (0)
VALGRIND_MAKE_MEM_NOACCESS(pool_tc->hdr.c.pool, flen);
#endif
#define TC_INVALIDATE_POOL(_pool_tc) do { \
TC_INVALIDATE_FILL_POOL(_pool_tc); \
TC_INVALIDATE_VALGRIND_POOL(_pool_tc); \
} while (0)
static unsigned int *talloc_pool_objectcount(struct talloc_chunk *tc)
{
return (unsigned int *)((char *)tc + TC_HDR_SIZE);
}
/*
@ -489,7 +490,7 @@ static unsigned int *talloc_pool_objectcount(struct talloc_chunk *tc)
static struct talloc_chunk *talloc_alloc_pool(struct talloc_chunk *parent,
size_t size)
{
struct talloc_chunk *pool_ctx = NULL;
union talloc_pool_chunk *pool_ctx = NULL;
size_t space_left;
struct talloc_chunk *result;
size_t chunk_size;
@ -499,17 +500,17 @@ static struct talloc_chunk *talloc_alloc_pool(struct talloc_chunk *parent,
}
if (parent->flags & TALLOC_FLAG_POOL) {
pool_ctx = parent;
pool_ctx = (union talloc_pool_chunk *)parent;
}
else if (parent->flags & TALLOC_FLAG_POOLMEM) {
pool_ctx = (struct talloc_chunk *)parent->pool;
pool_ctx = (union talloc_pool_chunk *)parent->pool;
}
if (pool_ctx == NULL) {
return NULL;
}
space_left = TC_POOL_SPACE_LEFT(pool_ctx);
space_left = tc_pool_space_left(pool_ctx);
/*
* Align size to 16 bytes
@ -520,18 +521,18 @@ static struct talloc_chunk *talloc_alloc_pool(struct talloc_chunk *parent,
return NULL;
}
result = (struct talloc_chunk *)pool_ctx->pool;
result = (struct talloc_chunk *)pool_ctx->hdr.c.pool;
#if defined(DEVELOPER) && defined(VALGRIND_MAKE_MEM_UNDEFINED)
VALGRIND_MAKE_MEM_UNDEFINED(result, size);
#endif
pool_ctx->pool = (void *)((char *)result + chunk_size);
pool_ctx->hdr.c.pool = (void *)((char *)result + chunk_size);
result->flags = TALLOC_MAGIC | TALLOC_FLAG_POOLMEM;
result->pool = pool_ctx;
*talloc_pool_objectcount(pool_ctx) += 1;
pool_ctx->hdr.object_count++;
return result;
}
@ -595,21 +596,20 @@ static inline void *__talloc(const void *context, size_t size)
_PUBLIC_ void *talloc_pool(const void *context, size_t size)
{
void *result = __talloc(context, size + TALLOC_POOL_HDR_SIZE);
struct talloc_chunk *tc;
union talloc_pool_chunk *pool_tc;
void *result = __talloc(context, sizeof(*pool_tc) - TC_HDR_SIZE + size);
if (unlikely(result == NULL)) {
return NULL;
}
tc = talloc_chunk_from_ptr(result);
pool_tc = (union talloc_pool_chunk *)talloc_chunk_from_ptr(result);
pool_tc->hdr.c.flags |= TALLOC_FLAG_POOL;
pool_tc->hdr.c.pool = tc_pool_first_chunk(pool_tc);
tc->flags |= TALLOC_FLAG_POOL;
tc->pool = TC_POOL_FIRST_CHUNK(tc);
pool_tc->hdr.object_count = 1;
*talloc_pool_objectcount(tc) = 1;
TC_INVALIDATE_POOL(tc);
tc_invalidate_pool(pool_tc);
return result;
}
@ -712,12 +712,11 @@ static void *_talloc_steal_internal(const void *new_ctx, const void *ptr);
static inline void _talloc_free_poolmem(struct talloc_chunk *tc,
const char *location)
{
struct talloc_chunk *pool;
union talloc_pool_chunk *pool;
void *next_tc;
unsigned int *pool_object_count;
pool = (struct talloc_chunk *)tc->pool;
next_tc = TC_POOLMEM_NEXT_CHUNK(tc);
pool = (union talloc_pool_chunk *)tc->pool;
next_tc = tc_next_chunk(tc);
tc->flags |= TALLOC_FLAG_FREE;
@ -729,16 +728,15 @@ static inline void _talloc_free_poolmem(struct talloc_chunk *tc,
TC_INVALIDATE_FULL_CHUNK(tc);
pool_object_count = talloc_pool_objectcount(pool);
if (unlikely(*pool_object_count == 0)) {
if (unlikely(pool->hdr.object_count == 0)) {
talloc_abort("Pool object count zero!");
return;
}
*pool_object_count -= 1;
pool->hdr.object_count--;
if (unlikely(*pool_object_count == 1 && !(pool->flags & TALLOC_FLAG_FREE))) {
if (unlikely(pool->hdr.object_count == 1
&& !(pool->hdr.c.flags & TALLOC_FLAG_FREE))) {
/*
* if there is just one object left in the pool
* and pool->flags does not have TALLOC_FLAG_FREE,
@ -746,25 +744,25 @@ static inline void _talloc_free_poolmem(struct talloc_chunk *tc,
* the rest is available for new objects
* again.
*/
pool->pool = TC_POOL_FIRST_CHUNK(pool);
TC_INVALIDATE_POOL(pool);
} else if (unlikely(*pool_object_count == 0)) {
pool->hdr.c.pool = tc_pool_first_chunk(pool);
tc_invalidate_pool(pool);
} else if (unlikely(pool->hdr.object_count == 0)) {
/*
* we mark the freed memory with where we called the free
* from. This means on a double free error we can report where
* the first free came from
*/
pool->name = location;
pool->hdr.c.name = location;
TC_INVALIDATE_FULL_CHUNK(pool);
TC_INVALIDATE_FULL_CHUNK(&pool->hdr.c);
free(pool);
} else if (pool->pool == next_tc) {
} else if (pool->hdr.c.pool == next_tc) {
/*
* if pool->pool still points to end of
* 'tc' (which is stored in the 'next_tc' variable),
* we can reclaim the memory of 'tc'.
*/
pool->pool = tc;
pool->hdr.c.pool = tc;
}
}
@ -854,18 +852,15 @@ static inline int _talloc_free_internal(void *ptr, const char *location)
tc->name = location;
if (tc->flags & TALLOC_FLAG_POOL) {
unsigned int *pool_object_count;
union talloc_pool_chunk *pool = (union talloc_pool_chunk *)tc;
pool_object_count = talloc_pool_objectcount(tc);
if (unlikely(*pool_object_count == 0)) {
if (unlikely(pool->hdr.object_count == 0)) {
talloc_abort("Pool object count zero!");
return 0;
}
*pool_object_count -= 1;
if (unlikely(*pool_object_count == 0)) {
pool->hdr.object_count--;
if (unlikely(pool->hdr.object_count == 0)) {
TC_INVALIDATE_FULL_CHUNK(tc);
free(tc);
}
@ -1380,7 +1375,7 @@ _PUBLIC_ void *_talloc_realloc(const void *context, void *ptr, size_t size, cons
struct talloc_chunk *tc;
void *new_ptr;
bool malloced = false;
struct talloc_chunk *pool_tc = NULL;
union talloc_pool_chunk *pool_tc = NULL;
/* size zero is equivalent to free() */
if (unlikely(size == 0)) {
@ -1409,20 +1404,21 @@ _PUBLIC_ void *_talloc_realloc(const void *context, void *ptr, size_t size, cons
return NULL;
}
/* don't let anybody try to realloc a talloc_pool */
/* handle realloc inside a talloc_pool */
if (unlikely(tc->flags & TALLOC_FLAG_POOLMEM)) {
pool_tc = (struct talloc_chunk *)tc->pool;
pool_tc = (union talloc_pool_chunk *)tc->pool;
}
#if (ALWAYS_REALLOC == 0)
/* don't shrink if we have less than 1k to gain */
if (size < tc->size) {
if (pool_tc) {
void *next_tc = TC_POOLMEM_NEXT_CHUNK(tc);
void *next_tc = tc_next_chunk(tc);
TC_INVALIDATE_SHRINK_CHUNK(tc, size);
tc->size = size;
if (next_tc == pool_tc->pool) {
pool_tc->pool = TC_POOLMEM_NEXT_CHUNK(tc);
if (next_tc == pool_tc->hdr.c.pool) {
/* note: tc->size has changed, so this works */
pool_tc->hdr.c.pool = tc_next_chunk(tc);
}
return ptr;
} else if ((tc->size - size) < 1024) {
@ -1455,7 +1451,7 @@ _PUBLIC_ void *_talloc_realloc(const void *context, void *ptr, size_t size, cons
#if ALWAYS_REALLOC
if (pool_tc) {
new_ptr = talloc_alloc_pool(tc, size + TC_HDR_SIZE);
*talloc_pool_objectcount(pool_tc) -= 1;
pool_tc->hdr.object_count--;
if (new_ptr == NULL) {
new_ptr = malloc(TC_HDR_SIZE+size);
@ -1475,14 +1471,14 @@ _PUBLIC_ void *_talloc_realloc(const void *context, void *ptr, size_t size, cons
}
#else
if (pool_tc) {
void *next_tc = TC_POOLMEM_NEXT_CHUNK(tc);
size_t old_chunk_size = TC_POOLMEM_CHUNK_SIZE(tc);
void *next_tc = tc_next_chunk(tc);
size_t old_chunk_size = TC_ALIGN16(TC_HDR_SIZE + tc->size);
size_t new_chunk_size = TC_ALIGN16(TC_HDR_SIZE + size);
size_t space_needed;
size_t space_left;
unsigned int chunk_count = *talloc_pool_objectcount(pool_tc);
unsigned int chunk_count = pool_tc->hdr.object_count;
if (!(pool_tc->flags & TALLOC_FLAG_FREE)) {
if (!(pool_tc->hdr.c.flags & TALLOC_FLAG_FREE)) {
chunk_count -= 1;
}
@ -1491,27 +1487,15 @@ _PUBLIC_ void *_talloc_realloc(const void *context, void *ptr, size_t size, cons
* optimize for the case where 'tc' is the only
* chunk in the pool.
*/
char *start = tc_pool_first_chunk(pool_tc);
space_needed = new_chunk_size;
space_left = pool_tc->size - TALLOC_POOL_HDR_SIZE;
space_left = (char *)tc_pool_end(pool_tc) - start;
if (space_left >= space_needed) {
size_t old_used = TC_HDR_SIZE + tc->size;
size_t new_used = TC_HDR_SIZE + size;
pool_tc->pool = TC_POOL_FIRST_CHUNK(pool_tc);
#if defined(DEVELOPER) && defined(VALGRIND_MAKE_MEM_UNDEFINED)
/*
* we need to prepare the memmove into
* the unaccessable area.
*/
{
size_t diff = PTR_DIFF(tc, pool_tc->pool);
size_t flen = MIN(diff, old_used);
char *fptr = (char *)pool_tc->pool;
VALGRIND_MAKE_MEM_UNDEFINED(fptr, flen);
}
#endif
memmove(pool_tc->pool, tc, old_used);
new_ptr = pool_tc->pool;
new_ptr = start;
memmove(new_ptr, tc, old_used);
tc = (struct talloc_chunk *)new_ptr;
TC_UNDEFINE_GROW_CHUNK(tc, size);
@ -1521,11 +1505,11 @@ _PUBLIC_ void *_talloc_realloc(const void *context, void *ptr, size_t size, cons
* because we want to invalidate the padding
* too.
*/
pool_tc->pool = new_used + (char *)new_ptr;
TC_INVALIDATE_POOL(pool_tc);
pool_tc->hdr.c.pool = new_used + (char *)new_ptr;
tc_invalidate_pool(pool_tc);
/* now the aligned pointer */
pool_tc->pool = new_chunk_size + (char *)new_ptr;
pool_tc->hdr.c.pool = new_chunk_size + (char *)new_ptr;
goto got_new_ptr;
}
@ -1539,19 +1523,19 @@ _PUBLIC_ void *_talloc_realloc(const void *context, void *ptr, size_t size, cons
return ptr;
}
if (next_tc == pool_tc->pool) {
if (next_tc == pool_tc->hdr.c.pool) {
/*
* optimize for the case where 'tc' is the last
* chunk in the pool.
*/
space_needed = new_chunk_size - old_chunk_size;
space_left = TC_POOL_SPACE_LEFT(pool_tc);
space_left = tc_pool_space_left(pool_tc);
if (space_left >= space_needed) {
TC_UNDEFINE_GROW_CHUNK(tc, size);
tc->flags &= ~TALLOC_FLAG_FREE;
tc->size = size;
pool_tc->pool = TC_POOLMEM_NEXT_CHUNK(tc);
pool_tc->hdr.c.pool = tc_next_chunk(tc);
return ptr;
}
}

2
lib/talloc/testsuite.c
View File

@ -848,7 +848,7 @@ static bool test_speed(void)
p1 = talloc_size(ctx, loop % 100);
p2 = talloc_strdup(p1, "foo bar");
p3 = talloc_size(p1, 300);
talloc_free_children(ctx);
talloc_free(p1);
}
count += 3 * loop;
} while (timeval_elapsed(&tv) < 5.0);