#include <string.h>
#include <limits.h>
#include <assert.h>
+#include <stdlib.h>
#include "alloc.h"
#include "build_assert/build_assert.h"
#include "config.h"
+/* FIXME: We assume getpagesize() doesnt change. Remapping file with
+ * different pagesize should still work. */
#if HAVE_ALIGNOF
#define ALIGNOF(t) __alignof__(t)
#else
/* File layout:
*
- * file := pagestates pad metadata
+ * file := pagestates pad uniform-cache metadata
* pagestates := pages * 2-bits-per-page
- * pad := pad to next ALIGNOF(metadata)
+ * pad := pad to next ALIGNOF(metaheader)
*
* metadata := metalen next-ptr metabits
- * metabits := freeblock | bitblock
- * freeblock := 0+
- * bitblock := 2-bits-per-bit-in-page 1
+ * metabits := freeblock | bitblock | uniformblock
+ * freeblock := FREE +
+ * bitblock := BITMAP + 2-bits-per-bit-in-page + pad-to-byte
+ * uniformblock := UNIFORM + 14-bit-byte-len + bits + pad-to-byte
*/
+#define UNIFORM_CACHE_NUM 16
+struct uniform_cache
+{
+ uint16_t size[UNIFORM_CACHE_NUM];
+ /* These could be u32 if we're prepared to limit size. */
+ unsigned long page[UNIFORM_CACHE_NUM];
+};
+
struct metaheader
{
/* Next meta header, or 0 */
return (x + a - 1) & ~(a - 1);
}
+static unsigned long align_down(unsigned long x, unsigned long a)
+{
+ return x & ~(a - 1);
+}
+
static unsigned long div_up(unsigned long x, unsigned long a)
{
return (x + a - 1) / a;
enum sub_metadata_type
{
/* FREE is same as alloc state */
- BITMAP = 1,
+ BITMAP = 1, /* bitmap allocated page */
+ UNIFORM, /* uniform size allocated page */
};
/* Page states are represented by bitpairs, at the start of the pool. */
#define BITS_PER_PAGE 2
+static uint8_t *get_page_statebits(const void *pool)
+{
+ return (uint8_t *)pool + sizeof(struct uniform_cache);
+}
+
static enum alloc_state get_page_state(const void *pool, unsigned long page)
{
- return get_bit_pair(pool, page);
+ return get_bit_pair(get_page_statebits(pool), page);
}
static void set_page_state(void *pool, unsigned long page, enum alloc_state s)
{
- set_bit_pair(pool, page, s);
+ set_bit_pair(get_page_statebits(pool), page, s);
}
/* The offset of metadata for a subpage allocation is found at the end
pagestatelen = align_up(div_up(poolsize/getpagesize() * BITS_PER_PAGE,
CHAR_BIT),
ALIGNOF(struct metaheader));
- return (struct metaheader *)((char *)pool + pagestatelen);
+ return (struct metaheader *)(get_page_statebits(pool) + pagestatelen);
}
static struct metaheader *next_mheader(void *pool, struct metaheader *mh)
mh = first_mheader(pool, poolsize);
- /* Mark all page states FREE, and all of metaheader bitmap which takes
- * rest of first page. */
+ /* Mark all page states FREE, all uniform caches zero, and all of
+ * metaheader bitmap which takes rest of first page. */
len = align_up(pool_offset(pool, mh + 1), getpagesize());
BUILD_ASSERT(FREE == 0);
memset(pool, 0, len);
static unsigned long alloc_get_pages(void *pool, unsigned long poolsize,
unsigned long pages, unsigned long align)
{
- return alloc_from_bitmap(pool, 0, poolsize / getpagesize(), pages,
+ return alloc_from_bitmap(get_page_statebits(pool),
+ 0, poolsize / getpagesize(), pages,
align / getpagesize());
}
{
uint8_t *bits = get_page_metadata(pool, page);
unsigned long i;
+ enum sub_metadata_type type;
+
+ type = get_bit_pair(bits, 0);
- /* TAKEN at start means a bitwise alloc. */
- assert(get_bit_pair(bits, 0) == BITMAP);
+ /* If this is a uniform page, we can't allocate from it. */
+ if (type == UNIFORM)
+ return 0;
+
+ assert(type == BITMAP);
/* We use a standart bitmap, but offset because of that BITMAP
* header. */
return i * getpagesize() - pool_offset(pool, mh + 1);
}
+static unsigned int uniform_metalen(unsigned int usize)
+{
+ unsigned int metalen;
+
+ assert(usize < (1 << 14));
+
+ /* Two bits for the header, 14 bits for size, then one bit for each
+ * element the page can hold. Round up to number of bytes. */
+ metalen = div_up(2*CHAR_BIT + SUBPAGE_METAOFF / usize, CHAR_BIT);
+
+ /* To ensure metaheader is always aligned, round bytes up. */
+ metalen = align_up(metalen, ALIGNOF(struct metaheader));
+
+ return metalen;
+}
+
+static unsigned int decode_usize(uint8_t *meta)
+{
+ return ((unsigned)meta[1] << (CHAR_BIT-2)) | (meta[0] >> 2);
+}
+
+static void encode_usize(uint8_t *meta, unsigned int usize)
+{
+ meta[0] = (UNIFORM | (usize << 2));
+ meta[1] = (usize >> (CHAR_BIT - 2));
+}
+
static uint8_t *alloc_metaspace(void *pool, unsigned long poolsize,
struct metaheader *mh, unsigned long bytes,
enum sub_metadata_type type)
metalen = get_metalen(pool, poolsize, mh);
- /* TAKEN tags end a subpage alloc. */
+ /* Walk through metadata looking for free. */
for (i = 0; i < metalen * CHAR_BIT / BITS_PER_PAGE; i += len) {
switch (get_bit_pair(meta, i)) {
case FREE:
len = BITMAP_METALEN * CHAR_BIT / BITS_PER_PAGE;
free = 0;
break;
+ case UNIFORM:
+ /* Figure metalen given usize. */
+ len = decode_usize(meta + i * BITS_PER_PAGE / CHAR_BIT);
+ len = uniform_metalen(len) * CHAR_BIT / BITS_PER_PAGE;
+ free = 0;
+ break;
default:
assert(0);
return NULL;
{
struct metaheader *mh, *newmh;
unsigned long page;
+ uint8_t *meta;
- for (mh = first_mheader(pool,poolsize); mh; mh = next_mheader(pool,mh)){
- uint8_t *meta = alloc_metaspace(pool, poolsize, mh, bytes,type);
-
- if (meta)
+ for (mh = first_mheader(pool,poolsize); mh; mh = next_mheader(pool,mh))
+ if ((meta = alloc_metaspace(pool, poolsize, mh, bytes, type)))
return meta;
- }
/* No room for metadata? Can we expand an existing one? */
for (mh = first_mheader(pool,poolsize); mh; mh = next_mheader(pool,mh)){
/* We start on this page. */
nextpage = pool_offset(pool, (char *)(mh+1))/getpagesize();
/* Iterate through any other pages we own. */
- while (get_page_state(pool, ++nextpage) == TAKEN)
+ while (get_page_state(pool, ++nextpage) == TAKEN);
/* Now, can we grab that page? */
if (get_page_state(pool, nextpage) != FREE)
set_page_state(pool, pagenum, FREE);
}
+static void maybe_transform_uniform_page(void *pool, unsigned long offset)
+{
+ /* FIXME: If possible and page isn't full, change to a bitmap */
+}
+
+/* Returns 0 or the size of the uniform alloc to use */
+static unsigned long suitable_for_uc(unsigned long size, unsigned long align)
+{
+ unsigned long num_elems, wastage, usize;
+ unsigned long bitmap_cost;
+
+ if (size == 0)
+ size = 1;
+
+ /* Fix up silly alignments. */
+ usize = align_up(size, align);
+
+ /* How many can fit in this page? */
+ num_elems = SUBPAGE_METAOFF / usize;
+
+ /* Can happen with bigger alignments. */
+ if (!num_elems)
+ return 0;
+
+ /* Usize maxes out at 14 bits. */
+ if (usize >= (1 << 14))
+ return 0;
+
+ /* How many bytes would be left at the end? */
+ wastage = SUBPAGE_METAOFF % usize;
+
+ /* If we can get a larger allocation within alignment constraints, we
+ * should do it, otherwise might as well leave wastage at the end. */
+ usize += align_down(wastage / num_elems, align);
+
+ /* Bitmap allocation costs 2 bits per BITMAP_GRANULARITY bytes, plus
+ * however much we waste in rounding up to BITMAP_GRANULARITY. */
+ bitmap_cost = 2 * div_up(size, BITMAP_GRANULARITY)
+ + CHAR_BIT * (align_up(size, BITMAP_GRANULARITY) - size);
+
+ /* Our cost is 1 bit, plus usize overhead */
+ if (bitmap_cost < 1 + (usize - size) * CHAR_BIT)
+ return 0;
+
+ return usize;
+}
+
+static unsigned long uniform_alloc(void *pool, unsigned long poolsize,
+ struct uniform_cache *uc,
+ unsigned long ucnum)
+{
+ uint8_t *metadata = get_page_metadata(pool, uc->page[ucnum]) + 2;
+ unsigned long i, max;
+
+ /* Simple one-bit-per-object bitmap. */
+ max = SUBPAGE_METAOFF / uc->size[ucnum];
+ for (i = 0; i < max; i++) {
+ if (!(metadata[i / CHAR_BIT] & (1 << (i % CHAR_BIT)))) {
+ metadata[i / CHAR_BIT] |= (1 << (i % CHAR_BIT));
+ return uc->page[ucnum] * getpagesize()
+ + i * uc->size[ucnum];
+ }
+ }
+
+ return 0;
+}
+
+static unsigned long new_uniform_page(void *pool, unsigned long poolsize,
+ unsigned long usize)
+{
+ unsigned long page, metalen;
+ uint8_t *metadata;
+
+ page = alloc_get_pages(pool, poolsize, 1, 1);
+ if (page == 0)
+ return 0;
+
+ metalen = uniform_metalen(usize);
+
+ /* Get metadata for page. */
+ metadata = new_metadata(pool, poolsize, metalen, UNIFORM);
+ if (!metadata) {
+ alloc_free_pages(pool, page);
+ return 0;
+ }
+
+ encode_usize(metadata, usize);
+
+ BUILD_ASSERT(FREE == 0);
+ memset(metadata + 2, 0, metalen - 2);
+
+ /* Actually, this is a subpage page now. */
+ set_page_state(pool, page, SPECIAL);
+
+ /* Set metadata pointer for page. */
+ set_page_metadata(pool, page, metadata);
+
+ return page;
+}
+
static unsigned long alloc_sub_page(void *pool, unsigned long poolsize,
unsigned long size, unsigned long align)
{
- unsigned long i;
+ unsigned long i, usize;
uint8_t *metadata;
+ struct uniform_cache *uc = pool;
+
+ usize = suitable_for_uc(size, align);
+ if (usize) {
+ /* Look for a uniform page. */
+ for (i = 0; i < UNIFORM_CACHE_NUM; i++) {
+ if (uc->size[i] == usize) {
+ unsigned long ret;
+ ret = uniform_alloc(pool, poolsize, uc, i);
+ if (ret != 0)
+ return ret;
+ /* OK, that one is full, remove from cache. */
+ uc->size[i] = 0;
+ break;
+ }
+ }
+
+ /* OK, try a new uniform page. Use random discard for now. */
+ i = random() % UNIFORM_CACHE_NUM;
+ maybe_transform_uniform_page(pool, uc->page[i]);
+
+ uc->page[i] = new_uniform_page(pool, poolsize, usize);
+ if (uc->page[i]) {
+ uc->size[i] = usize;
+ return uniform_alloc(pool, poolsize, uc, i);
+ }
+ uc->size[i] = 0;
+ }
/* Look for partial page. */
for (i = 0; i < poolsize / getpagesize(); i++) {
return sub_page_alloc(pool, i, size, align);
}
+static bool bitmap_page_is_empty(uint8_t *meta)
+{
+ unsigned int i;
+
+ /* Skip the header (first bit of metadata). */
+ for (i = 1; i < SUBPAGE_METAOFF/BITMAP_GRANULARITY+1; i++)
+ if (get_bit_pair(meta, i) != FREE)
+ return false;
+
+ return true;
+}
+
+static bool uniform_page_is_empty(uint8_t *meta)
+{
+ unsigned int i, metalen;
+
+ metalen = uniform_metalen(decode_usize(meta));
+
+ /* Skip the header (first two bytes of metadata). */
+ for (i = 2; i < metalen + 2; i++) {
+ BUILD_ASSERT(FREE == 0);
+ if (meta[i])
+ return false;
+ }
+ return true;
+}
+
+static bool special_page_is_empty(void *pool, unsigned long page)
+{
+ uint8_t *meta;
+ enum sub_metadata_type type;
+
+ meta = get_page_metadata(pool, page);
+ type = get_bit_pair(meta, 0);
+
+ switch (type) {
+ case UNIFORM:
+ return uniform_page_is_empty(meta);
+ case BITMAP:
+ return bitmap_page_is_empty(meta);
+ default:
+ assert(0);
+ }
+}
+
+static void clear_special_metadata(void *pool, unsigned long page)
+{
+ uint8_t *meta;
+ enum sub_metadata_type type;
+
+ meta = get_page_metadata(pool, page);
+ type = get_bit_pair(meta, 0);
+
+ switch (type) {
+ case UNIFORM:
+ /* First two bytes are the header, rest is already FREE */
+ BUILD_ASSERT(FREE == 0);
+ memset(meta, 0, 2);
+ break;
+ case BITMAP:
+ /* First two bits is the header. */
+ BUILD_ASSERT(BITMAP_METALEN > 1);
+ meta[0] = 0;
+ break;
+ default:
+ assert(0);
+ }
+}
+
/* Returns true if we cleaned any pages. */
static bool clean_empty_subpages(void *pool, unsigned long poolsize)
{
bool progress = false;
for (i = 0; i < poolsize/getpagesize(); i++) {
- uint8_t *meta;
- unsigned int j;
if (get_page_state(pool, i) != SPECIAL)
continue;
- meta = get_page_metadata(pool, i);
- /* Skip the header (first bit of metadata). */
- for (j = 1; j < SUBPAGE_METAOFF/BITMAP_GRANULARITY+1; j++)
- if (get_bit_pair(meta, j) != FREE)
- break;
-
- /* So, is this page totally empty? */
- if (j == SUBPAGE_METAOFF/BITMAP_GRANULARITY+1) {
+ if (special_page_is_empty(pool, i)) {
+ clear_special_metadata(pool, i);
set_page_state(pool, i, FREE);
progress = true;
}
return NULL;
}
-static void subpage_free(void *pool, unsigned long pagenum, void *free)
+static void bitmap_free(void *pool, unsigned long pagenum, unsigned long off,
+ uint8_t *metadata)
{
- unsigned long off = (unsigned long)free % getpagesize();
- uint8_t *metadata;
-
- assert(off < SUBPAGE_METAOFF);
assert(off % BITMAP_GRANULARITY == 0);
- metadata = get_page_metadata(pool, pagenum);
-
off /= BITMAP_GRANULARITY;
/* Offset by one because first bit is used for header. */
set_bit_pair(metadata, off++, FREE);
}
+static void uniform_free(void *pool, unsigned long pagenum, unsigned long off,
+ uint8_t *metadata)
+{
+ unsigned int usize, bit;
+
+ usize = decode_usize(metadata);
+ /* Must have been this size. */
+ assert(off % usize == 0);
+ bit = off / usize;
+
+ /* Skip header. */
+ metadata += 2;
+
+ /* Must have been allocated. */
+ assert(metadata[bit / CHAR_BIT] & (1 << (bit % CHAR_BIT)));
+ metadata[bit / CHAR_BIT] &= ~(1 << (bit % CHAR_BIT));
+}
+
+static void subpage_free(void *pool, unsigned long pagenum, void *free)
+{
+ unsigned long off = (unsigned long)free % getpagesize();
+ uint8_t *metadata = get_page_metadata(pool, pagenum);
+ enum sub_metadata_type type;
+
+ type = get_bit_pair(metadata, 0);
+
+ assert(off < SUBPAGE_METAOFF);
+
+ switch (type) {
+ case BITMAP:
+ bitmap_free(pool, pagenum, off, metadata);
+ break;
+ case UNIFORM:
+ uniform_free(pool, pagenum, off, metadata);
+ break;
+ default:
+ assert(0);
+ }
+}
+
void alloc_free(void *pool, unsigned long poolsize, void *free)
{
unsigned long pagenum;
return false;
}
-static bool check_subpage(void *pool, unsigned long poolsize,
- unsigned long page)
+static bool check_bitmap_metadata(void *pool, unsigned long *mhoff)
{
- unsigned long *mhoff = metadata_off(pool, page);
- unsigned int i;
enum alloc_state last_state = FREE;
-
- if (*mhoff + sizeof(struct metaheader) > poolsize)
- return false;
-
- if (*mhoff % ALIGNOF(struct metaheader) != 0)
- return false;
-
- /* It must point to a metadata page. */
- if (!is_metadata_page(pool, poolsize, *mhoff / getpagesize()))
- return false;
-
- /* Header at start of subpage allocation */
- if (get_bit_pair((uint8_t *)pool + *mhoff, 0) != BITMAP)
- return false;
+ unsigned int i;
for (i = 0; i < SUBPAGE_METAOFF / BITMAP_GRANULARITY; i++) {
enum alloc_state state;
return true;
}
+static bool check_uniform_metadata(void *pool, unsigned long *mhoff)
+{
+ uint8_t *meta = (uint8_t *)pool + *mhoff;
+ unsigned int i, usize;
+ struct uniform_cache *uc = pool;
+
+ usize = decode_usize(meta);
+ if (usize == 0 || suitable_for_uc(usize, 1) != usize)
+ return false;
+
+ /* If it's in uniform cache, make sure that agrees on size. */
+ for (i = 0; i < UNIFORM_CACHE_NUM; i++) {
+ uint8_t *ucm;
+
+ if (!uc->size[i])
+ continue;
+
+ ucm = get_page_metadata(pool, uc->page[i]);
+ if (ucm != meta)
+ continue;
+
+ if (usize != uc->size[i])
+ return false;
+ }
+ return true;
+}
+
+static bool check_subpage(void *pool, unsigned long poolsize,
+ unsigned long page)
+{
+ unsigned long *mhoff = metadata_off(pool, page);
+
+ if (*mhoff + sizeof(struct metaheader) > poolsize)
+ return false;
+
+ if (*mhoff % ALIGNOF(struct metaheader) != 0)
+ return false;
+
+ /* It must point to a metadata page. */
+ if (!is_metadata_page(pool, poolsize, *mhoff / getpagesize()))
+ return false;
+
+ /* Header at start of subpage allocation */
+ switch (get_bit_pair((uint8_t *)pool + *mhoff, 0)) {
+ case BITMAP:
+ return check_bitmap_metadata(pool, mhoff);
+ case UNIFORM:
+ return check_uniform_metadata(pool, mhoff);
+ default:
+ return false;
+ }
+
+}
+
bool alloc_check(void *pool, unsigned long poolsize)
{
unsigned long i;
void alloc_visualize(FILE *out, void *pool, unsigned long poolsize)
{
struct metaheader *mh;
+ struct uniform_cache *uc = pool;
unsigned long pagebitlen, metadata_pages, count[1<<BITS_PER_PAGE], tot;
long i;
return;
}
+ tot = 0;
+ for (i = 0; i < UNIFORM_CACHE_NUM; i++)
+ tot += (uc->size[i] != 0);
+ fprintf(out, "Uniform cache (%lu entries):\n", tot);
+ for (i = 0; i < UNIFORM_CACHE_NUM; i++) {
+ unsigned int j, total = 0;
+ uint8_t *meta;
+
+ if (!uc->size[i])
+ continue;
+
+ /* First two bytes are header. */
+ meta = get_page_metadata(pool, uc->page[i]) + 2;
+
+ for (j = 0; j < SUBPAGE_METAOFF / uc->size[i]; j++)
+ if (meta[j / 8] & (1 << (j % 8)))
+ total++;
+
+ printf(" %u: %u/%u (%u%% density)\n",
+ uc->size[j], total, SUBPAGE_METAOFF / uc->size[i],
+ (total * 100) / (SUBPAGE_METAOFF / uc->size[i]));
+ }
+
memset(count, 0, sizeof(count));
for (i = 0; i < poolsize / getpagesize(); i++)
count[get_page_state(pool, i)]++;
mh = first_mheader(pool, poolsize);
- pagebitlen = (char *)mh - (char *)pool;
+ pagebitlen = (uint8_t *)mh - get_page_statebits(pool);
fprintf(out, "%lu bytes of page bits: FREE/TAKEN/TAKEN_START/SUBPAGE = %lu/%lu/%lu/%lu\n",
pagebitlen, count[0], count[1], count[2], count[3]);
/* Now do each metadata page. */
for (; mh; mh = next_mheader(pool,mh)) {
- unsigned long free = 0, subpageblocks = 0, len = 0, metalen;
+ unsigned long free = 0, bitmapblocks = 0, uniformblocks = 0,
+ len = 0, uniformlen = 0, bitmaplen = 0, metalen;
uint8_t *meta = (uint8_t *)(mh + 1);
metalen = get_metalen(pool, poolsize, mh);
metadata_pages += (sizeof(*mh) + metalen) / getpagesize();
for (i = 0; i < metalen * CHAR_BIT / BITS_PER_PAGE; i += len) {
- switch (get_page_state(meta, i)) {
+ switch (get_bit_pair(meta, i)) {
case FREE:
len = 1;
free++;
case BITMAP:
/* Skip over this allocated part. */
len = BITMAP_METALEN * CHAR_BIT;
- subpageblocks++;
+ bitmapblocks++;
+ bitmaplen += len;
+ break;
+ case UNIFORM:
+ /* Skip over this part. */
+ len = decode_usize(meta + i * BITS_PER_PAGE / CHAR_BIT);
+ len = uniform_metalen(len) * CHAR_BIT / BITS_PER_PAGE;
+ uniformblocks++;
+ uniformlen += len;
break;
default:
assert(0);
}
}
- fprintf(out, "Metadata %lu-%lu: %lu free, %lu subpageblocks, %lu%% density\n",
+ fprintf(out, "Metadata %lu-%lu: %lu free, %lu bitmapblocks, %lu uniformblocks, %lu%% density\n",
pool_offset(pool, mh),
pool_offset(pool, (char *)(mh+1) + metalen),
- free, subpageblocks,
- subpageblocks * BITMAP_METALEN * 100
- / (free + subpageblocks * BITMAP_METALEN));
+ free, bitmapblocks, uniformblocks,
+ (bitmaplen + uniformlen) * 100
+ / (free + bitmaplen + uniformlen));
}
/* Account for total pages allocated. */
/* Now do every subpage. */
for (i = 0; i < poolsize / getpagesize(); i++) {
uint8_t *meta;
- unsigned int j;
+ unsigned int j, allocated;
+ enum sub_metadata_type type;
+
if (get_page_state(pool, i) != SPECIAL)
continue;
memset(count, 0, sizeof(count));
+
meta = get_page_metadata(pool, i);
- for (j = 0; j < SUBPAGE_METAOFF/BITMAP_GRANULARITY; j++)
- count[get_page_state(meta, j)]++;
+ type = get_bit_pair(meta, 0);
- fprintf(out, "Subpage %lu: "
- "FREE/TAKEN/TAKEN_START = %lu/%lu/%lu %lu%% density\n",
+ if (type == BITMAP) {
+ for (j = 0; j < SUBPAGE_METAOFF/BITMAP_GRANULARITY; j++)
+ count[get_page_state(meta, j)]++;
+ allocated = (count[1] + count[2]) * BITMAP_GRANULARITY;
+ fprintf(out, "Subpage bitmap ");
+ } else {
+ unsigned int usize = decode_usize(meta);
+
+ assert(type == UNIFORM);
+ fprintf(out, "Subpage uniform (%u) ", usize);
+ meta += 2;
+ for (j = 0; j < SUBPAGE_METAOFF / usize; j++)
+ count[!!(meta[j / 8] & (1 << (j % 8)))]++;
+ allocated = count[1] * usize;
+ }
+ fprintf(out, "%lu: FREE/TAKEN/TAKEN_START = %lu/%lu/%lu %u%% density\n",
i, count[0], count[1], count[2],
- ((count[1] + count[2]) * BITMAP_GRANULARITY) * 100
- / getpagesize());
- tot += (count[1] + count[2]) * BITMAP_GRANULARITY;
+ allocated * 100 / getpagesize());
+ tot += allocated;
}
/* This is optimistic, since we overalloc in several cases. */
projects / ccan / blobdiff