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Commit 03a2acdd authored by Rusty Russell's avatar Rusty Russell
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Separate functions for bitpair manip.

parent b3d0388f
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Showing with 66 additions and 45 deletions
alloc/alloc.c
View file @ 03a2acdd
......@@ -42,25 +42,58 @@ struct metaheader
/* Bits start here. */
};
#define BITS_PER_PAGE 2
/* FIXME: Don't use page states for bitblock. It's tacky and confusing. */
enum page_state
/* Assumes a is a power of two. */
static unsigned long align_up(unsigned long x, unsigned long a)
{
return (x + a - 1) & ~(a - 1);
}
static unsigned long div_up(unsigned long x, unsigned long a)
{
return (x + a - 1) / a;
}
/* It turns out that we spend a lot of time dealing with bit pairs.
* These routines manipulate them.
*/
static uint8_t get_bit_pair(const uint8_t *bits, unsigned long index)
{
return bits[index * 2 / CHAR_BIT] >> (index * 2 % CHAR_BIT) & 3;
}
static void set_bit_pair(uint8_t *bits, unsigned long index, uint8_t val)
{
bits[index * 2 / CHAR_BIT] &= ~(3 << (index * 2 % CHAR_BIT));
bits[index * 2 / CHAR_BIT] |= (val << (index * 2 % CHAR_BIT));
}
/* This is used for page states and subpage allocations */
enum alloc_state
{
FREE,
TAKEN,
TAKEN_START,
SUBPAGE,
SPECIAL, /* Sub-page allocation for page states. */
};
/* Assumes a is a power of two. */
static unsigned long align_up(unsigned long x, unsigned long a)
/* The types for subpage metadata. */
enum sub_metadata_type
{
return (x + a - 1) & ~(a - 1);
/* FREE is same as alloc state */
BITMAP = 1,
};
/* Page states are represented by bitpairs, at the start of the pool. */
#define BITS_PER_PAGE 2
static enum alloc_state get_page_state(const void *pool, unsigned long page)
{
return get_bit_pair(pool, page);
}
static unsigned long div_up(unsigned long x, unsigned long a)
static void set_page_state(void *pool, unsigned long page, enum alloc_state s)
{
return (x + a - 1) / a;
set_bit_pair(pool, page, s);
}
/* The offset of metadata for a subpage allocation is found at the end
......@@ -69,24 +102,13 @@ static unsigned long div_up(unsigned long x, unsigned long a)
/* This is the length of metadata in bits. It consists of two bits
* for every BITMAP_GRANULARITY of usable bytes in the page, then two
* bits for the TAKEN tailer.. */
* bits for the tailer.. */
#define BITMAP_METABITLEN \
((div_up(SUBPAGE_METAOFF, BITMAP_GRANULARITY) + 1) * BITS_PER_PAGE)
/* This is the length in bytes. */
#define BITMAP_METALEN (div_up(BITMAP_METABITLEN, CHAR_BIT))
static enum page_state get_page_state(const uint8_t *bits, unsigned long page)
{
return bits[page * 2 / CHAR_BIT] >> (page * 2 % CHAR_BIT) & 3;
}
static void set_page_state(uint8_t *bits, unsigned long page, enum page_state s)
{
bits[page * 2 / CHAR_BIT] &= ~(3 << (page * 2 % CHAR_BIT));
bits[page * 2 / CHAR_BIT] |= ((uint8_t)s << (page * 2 % CHAR_BIT));
}
static struct metaheader *first_mheader(void *pool, unsigned long poolsize)
{
unsigned int pagestatelen;
......@@ -146,7 +168,7 @@ static long alloc_from_bitmap(uint8_t *bits, unsigned long elems,
free = 0;
/* We allocate from far end, to increase ability to expand metadata. */
for (i = elems - 1; i >= 0; i--) {
switch (get_page_state(bits, i)) {
switch (get_bit_pair(bits, i)) {
case FREE:
if (++free >= want) {
unsigned long j;
......@@ -156,12 +178,12 @@ static long alloc_from_bitmap(uint8_t *bits, unsigned long elems,
continue;
for (j = i+1; j < i + want; j++)
set_page_state(bits, j, TAKEN);
set_page_state(bits, i, TAKEN_START);
set_bit_pair(bits, j, TAKEN);
set_bit_pair(bits, i, TAKEN_START);
return i;
}
break;
case SUBPAGE:
case SPECIAL:
case TAKEN_START:
case TAKEN:
free = 0;
......@@ -198,7 +220,7 @@ static unsigned long alloc_get_pages(void *pool, unsigned long poolsize,
return i;
}
break;
case SUBPAGE:
case SPECIAL:
case TAKEN_START:
case TAKEN:
free = 0;
......@@ -233,8 +255,7 @@ static unsigned long sub_page_alloc(void *pool, unsigned long page,
long i;
/* TAKEN at end means a bitwise alloc. */
assert(get_page_state(bits, getpagesize()/BITMAP_GRANULARITY - 1)
== TAKEN);
assert(get_bit_pair(bits, getpagesize()/BITMAP_GRANULARITY-1) == TAKEN);
/* Our bits are the same as the page bits. */
i = alloc_from_bitmap(bits, SUBPAGE_METAOFF/BITMAP_GRANULARITY,
......@@ -256,7 +277,7 @@ static uint8_t *alloc_metaspace(struct metaheader *mh, unsigned long bytes)
/* TAKEN tags end a subpage alloc. */
for (i = mh->metalen * CHAR_BIT / BITS_PER_PAGE - 1; i >= 0; i -= len) {
switch (get_page_state(meta, i)) {
switch (get_bit_pair(meta, i)) {
case FREE:
len = 1;
free++;
......@@ -266,7 +287,7 @@ static uint8_t *alloc_metaspace(struct metaheader *mh, unsigned long bytes)
return meta + i / (CHAR_BIT / BITS_PER_PAGE);
}
break;
case TAKEN:
case BITMAP:
/* Skip over this allocated part. */
len = BITMAP_METALEN * CHAR_BIT / BITS_PER_PAGE;
free = 0;
......@@ -348,7 +369,7 @@ static unsigned long alloc_sub_page(void *pool, unsigned long poolsize,
/* Look for partial page. */
for (i = 0; i < poolsize / getpagesize(); i++) {
unsigned long ret;
if (get_page_state(pool, i) != SUBPAGE)
if (get_page_state(pool, i) != SPECIAL)
continue;
ret = sub_page_alloc(pool, i, size, align);
......@@ -368,8 +389,8 @@ static unsigned long alloc_sub_page(void *pool, unsigned long poolsize,
return 0;
}
/* Actually, this is a SUBPAGE page now. */
set_page_state(pool, i, SUBPAGE);
/* Actually, this is a subpage page now. */
set_page_state(pool, i, SPECIAL);
/* Set metadata pointer for page. */
set_page_metadata(pool, i, metadata);
......@@ -387,7 +408,7 @@ static bool clean_empty_subpages(void *pool, unsigned long poolsize)
for (i = 0; i < poolsize/getpagesize(); i++) {
uint8_t *meta;
unsigned int j;
if (get_page_state(pool, i) != SUBPAGE)
if (get_page_state(pool, i) != SPECIAL)
continue;
meta = get_page_metadata(pool, i);
......@@ -519,7 +540,7 @@ void alloc_free(void *pool, unsigned long poolsize, void *free)
pagenum = pool_offset(pool, free) / getpagesize();
if (get_page_state(pool, pagenum) == SUBPAGE)
if (get_page_state(pool, pagenum) == SPECIAL)
subpage_free(pool, pagenum, free);
else {
assert((unsigned long)free % getpagesize() == 0);
......@@ -548,7 +569,7 @@ static bool check_subpage(void *pool, unsigned long poolsize,
{
unsigned long *mhoff = metadata_off(pool, page);
unsigned int i;
enum page_state last_state = FREE;
enum alloc_state last_state = FREE;
if (*mhoff + sizeof(struct metaheader) > poolsize)
return false;
......@@ -561,16 +582,16 @@ static bool check_subpage(void *pool, unsigned long poolsize,
return false;
/* Marker at end of subpage allocation is "taken" */
if (get_page_state((uint8_t *)pool + *mhoff,
getpagesize()/BITMAP_GRANULARITY - 1) != TAKEN)
if (get_bit_pair((uint8_t *)pool + *mhoff,
getpagesize()/BITMAP_GRANULARITY - 1) != TAKEN)
return false;
for (i = 0; i < SUBPAGE_METAOFF / BITMAP_GRANULARITY; i++) {
enum page_state state;
enum alloc_state state;
state = get_page_state((uint8_t *)pool + *mhoff, i);
state = get_bit_pair((uint8_t *)pool + *mhoff, i);
switch (state) {
case SUBPAGE:
case SPECIAL:
return false;
case TAKEN:
if (last_state == FREE)
......@@ -588,7 +609,7 @@ bool alloc_check(void *pool, unsigned long poolsize)
{
unsigned long i;
struct metaheader *mh;
enum page_state last_state = FREE;
enum alloc_state last_state = FREE;
bool was_metadata = false;
if (poolsize < MIN_SIZE)
......@@ -621,7 +642,7 @@ bool alloc_check(void *pool, unsigned long poolsize)
}
for (i = 0; i < poolsize / getpagesize(); i++) {
enum page_state state = get_page_state(pool, i);
enum alloc_state state = get_page_state(pool, i);
bool is_metadata = is_metadata_page(pool, poolsize,i);
switch (state) {
......@@ -638,7 +659,7 @@ bool alloc_check(void *pool, unsigned long poolsize)
if (is_metadata != was_metadata)
return false;
break;
case SUBPAGE:
case SPECIAL:
/* Check metadata pointer etc. */
if (!check_subpage(pool, poolsize, i))
return false;
......@@ -716,7 +737,7 @@ void alloc_visualize(FILE *out, void *pool, unsigned long poolsize)
for (i = 0; i < poolsize / getpagesize(); i++) {
uint8_t *meta;
unsigned int j;
if (get_page_state(pool, i) != SUBPAGE)
if (get_page_state(pool, i) != SPECIAL)
continue;
memset(count, 0, sizeof(count));
......
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