#include <string.h>
#include <limits.h>
#include <assert.h>
+#include <stdlib.h>
#include "alloc.h"
+#include "build_assert/build_assert.h"
+#include "alignof/alignof.h"
+#include "config.h"
+
+/* FIXME: We assume getpagesize() doesnt change. Remapping file with
+ * different pagesize should still work. */
/* FIXME: Doesn't handle non-page-aligned poolsize. */
-/* FIXME: Doesn't handle sub-page allocations. */
+/* FIXME: Reduce. */
#define MIN_SIZE (getpagesize() * 2)
-enum page_state
+/* What's the granularity of sub-page allocs? */
+#define BITMAP_GRANULARITY 4
+
+/* File layout:
+ *
+ * file := pagestates pad uniform-cache metadata
+ * pagestates := pages * 2-bits-per-page
+ * pad := pad to next ALIGNOF(metaheader)
+ *
+ * metadata := metalen next-ptr metabits
+ * 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 */
+ unsigned long next;
+ /* Bits start here. */
+};
+
+/* 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 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;
+}
+
+/* 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,
+ SPECIAL, /* Sub-page allocation for page states. */
};
-void alloc_init(void *pool, unsigned long poolsize)
+/* The types for subpage metadata. */
+enum sub_metadata_type
{
- uint8_t *bits = pool;
- unsigned int pages = poolsize / getpagesize();
+ /* FREE is same as alloc state */
+ BITMAP = 1, /* bitmap allocated page */
+ UNIFORM, /* uniform size allocated page */
+};
- if (poolsize < MIN_SIZE)
- return;
+/* Page states are represented by bitpairs, at the start of the pool. */
+#define BITS_PER_PAGE 2
+
+/* How much metadata info per byte? */
+#define METADATA_PER_BYTE (CHAR_BIT / 2)
- memset(bits, 0, (pages * 2 + CHAR_BIT - 1)/ CHAR_BIT);
+static uint8_t *get_page_statebits(const void *pool)
+{
+ return (uint8_t *)pool + sizeof(struct uniform_cache);
}
-static enum page_state get_page_state(const uint8_t *bits, unsigned long page)
+static enum alloc_state get_page_state(const void *pool, unsigned long page)
{
- return bits[page * 2 / CHAR_BIT] >> (page * 2 % CHAR_BIT) & 3;
+ return get_bit_pair(get_page_statebits(pool), page);
}
-static void set_page_state(uint8_t *bits, unsigned long page, enum page_state s)
+static void set_page_state(void *pool, unsigned long page, enum alloc_state s)
{
- bits[page * 2 / CHAR_BIT] &= ~(3 << (page * 2 % CHAR_BIT));
- bits[page * 2 / CHAR_BIT] |= ((uint8_t)s << (page * 2 % CHAR_BIT));
+ set_bit_pair(get_page_statebits(pool), page, s);
}
-static unsigned long metadata_length(void *pool, unsigned long poolsize)
+/* The offset of metadata for a subpage allocation is found at the end
+ * of the subpage */
+#define SUBPAGE_METAOFF (getpagesize() - sizeof(unsigned long))
+
+/* 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 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 struct metaheader *first_mheader(void *pool, unsigned long poolsize)
{
- return ((poolsize / getpagesize() * 2 / CHAR_BIT) + getpagesize() - 1)
- & ~(getpagesize() - 1);
+ unsigned int pagestatelen;
+
+ pagestatelen = align_up(div_up(poolsize/getpagesize() * BITS_PER_PAGE,
+ CHAR_BIT),
+ ALIGNOF(struct metaheader));
+ return (struct metaheader *)(get_page_statebits(pool) + pagestatelen);
}
-void *alloc_get(void *pool, unsigned long poolsize,
- unsigned long size, unsigned long align)
+static struct metaheader *next_mheader(void *pool, struct metaheader *mh)
{
- long i;
- unsigned long free, want, metalen;
+ if (!mh->next)
+ return NULL;
+
+ return (struct metaheader *)((char *)pool + mh->next);
+}
+
+static unsigned long pool_offset(void *pool, void *p)
+{
+ return (char *)p - (char *)pool;
+}
+
+void alloc_init(void *pool, unsigned long poolsize)
+{
+ /* FIXME: Alignment assumptions about pool. */
+ unsigned long len, i;
+ struct metaheader *mh;
if (poolsize < MIN_SIZE)
- return NULL;
+ return;
- /* FIXME: Necessary for this. */
- if (size == 0)
- size = 1;
+ mh = first_mheader(pool, poolsize);
+
+ /* 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);
+
+ /* Mark the pagestate and metadata page(s) allocated. */
+ set_page_state(pool, 0, TAKEN_START);
+ for (i = 1; i < div_up(len, getpagesize()); i++)
+ set_page_state(pool, i, TAKEN);
+}
- want = (size + getpagesize() - 1) / getpagesize();
- metalen = metadata_length(pool, poolsize);
+/* Two bits per element, representing page states. Returns 0 on fail.
+ * off is used to allocate from subpage bitmaps, which use the first 2
+ * bits as the type, so the real bitmap is offset by 1. */
+static unsigned long alloc_from_bitmap(uint8_t *bits, unsigned long off,
+ unsigned long elems,
+ unsigned long want, unsigned long align)
+{
+ long i;
+ unsigned long free;
free = 0;
/* We allocate from far end, to increase ability to expand metadata. */
- for (i = (poolsize - metalen) / getpagesize() - 1; i >= 0; i--) {
- switch (get_page_state(pool, i)) {
+ for (i = elems - 1; i >= 0; i--) {
+ switch (get_bit_pair(bits, off+i)) {
case FREE:
if (++free >= want) {
unsigned long j;
- char *ret = (char *)pool + metalen
- + i * getpagesize();
- /* They might ask for multi-page alignment. */
- if ((unsigned long)ret % align)
+ /* They might ask for large alignment. */
+ if (align && i % align)
continue;
+ set_bit_pair(bits, off+i, TAKEN_START);
for (j = i+1; j < i + want; j++)
- set_page_state(pool, j, TAKEN);
- set_page_state(pool, i, TAKEN_START);
- return ret;
+ set_bit_pair(bits, off+j, TAKEN);
+ return off+i;
}
break;
+ case SPECIAL:
case TAKEN_START:
case TAKEN:
free = 0;
}
}
+ return 0;
+}
+
+static unsigned long alloc_get_pages(void *pool, unsigned long poolsize,
+ unsigned long pages, unsigned long align)
+{
+ return alloc_from_bitmap(get_page_statebits(pool),
+ 0, poolsize / getpagesize(), pages,
+ align / getpagesize());
+}
+
+/* Offset to metadata is at end of page. */
+static unsigned long *metadata_off(void *pool, unsigned long page)
+{
+ return (unsigned long *)
+ ((char *)pool + (page+1)*getpagesize() - sizeof(unsigned long));
+}
+
+static uint8_t *get_page_metadata(void *pool, unsigned long page)
+{
+ return (uint8_t *)pool + *metadata_off(pool, page);
+}
+
+static void set_page_metadata(void *pool, unsigned long page, uint8_t *meta)
+{
+ *metadata_off(pool, page) = meta - (uint8_t *)pool;
+}
+
+static unsigned long sub_page_alloc(void *pool, unsigned long page,
+ unsigned long size, unsigned long align)
+{
+ uint8_t *bits = get_page_metadata(pool, page);
+ unsigned long i;
+ enum sub_metadata_type type;
+
+ type = get_bit_pair(bits, 0);
+
+ /* 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. */
+ i = alloc_from_bitmap(bits, 1, SUBPAGE_METAOFF/BITMAP_GRANULARITY,
+ div_up(size, BITMAP_GRANULARITY),
+ align / BITMAP_GRANULARITY);
+
+ /* Can't allocate? */
+ if (i == 0)
+ return 0;
+
+ /* i-1 because of the header. */
+ return page*getpagesize() + (i-1)*BITMAP_GRANULARITY;
+}
+
+/* We look at the page states to figure out where the allocation for this
+ * metadata ends. */
+static unsigned long get_metalen(void *pool, unsigned long poolsize,
+ struct metaheader *mh)
+{
+ unsigned long i, first, pages = poolsize / getpagesize();
+
+ first = pool_offset(pool, mh + 1)/getpagesize();
+
+ for (i = first + 1; i < pages && get_page_state(pool,i) == TAKEN; i++);
+
+ 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 + 14 + 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)
+{
+ uint8_t *meta = (uint8_t *)(mh + 1);
+ unsigned long free = 0, len, i, metalen;
+
+ metalen = get_metalen(pool, poolsize, mh);
+
+ /* Walk through metadata looking for free. */
+ for (i = 0; i < metalen * METADATA_PER_BYTE; i += len) {
+ switch (get_bit_pair(meta, i)) {
+ case FREE:
+ len = 1;
+ free++;
+ if (free == bytes * METADATA_PER_BYTE) {
+ /* Mark this as a bitmap. */
+ set_bit_pair(meta, i - free + 1, type);
+ return meta + (i - free + 1)/METADATA_PER_BYTE;
+ }
+ break;
+ case BITMAP:
+ /* Skip over this allocated part. */
+ len = BITMAP_METALEN * METADATA_PER_BYTE;
+ free = 0;
+ break;
+ case UNIFORM:
+ /* Figure metalen given usize. */
+ len = decode_usize(meta + i / METADATA_PER_BYTE);
+ len = uniform_metalen(len) * METADATA_PER_BYTE;
+ free = 0;
+ break;
+ default:
+ assert(0);
+ return NULL;
+ }
+ }
return NULL;
}
-void alloc_free(void *pool, unsigned long poolsize, void *free)
+/* We need this many bytes of metadata. */
+static uint8_t *new_metadata(void *pool, unsigned long poolsize,
+ unsigned long bytes, enum sub_metadata_type type)
{
- unsigned long pagenum, metalen;
+ struct metaheader *mh, *newmh;
+ unsigned long page;
+ uint8_t *meta;
- if (poolsize < MIN_SIZE)
- return;
+ for (mh = first_mheader(pool,poolsize); mh; mh = next_mheader(pool,mh))
+ if ((meta = alloc_metaspace(pool, poolsize, mh, bytes, type)))
+ return meta;
- if (!free)
- return;
+ /* No room for metadata? Can we expand an existing one? */
+ for (mh = first_mheader(pool,poolsize); mh; mh = next_mheader(pool,mh)){
+ unsigned long nextpage;
+
+ /* 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);
- metalen = metadata_length(pool, poolsize);
+ /* Now, can we grab that page? */
+ if (get_page_state(pool, nextpage) != FREE)
+ continue;
- assert(free > pool && (char *)pool + poolsize > (char *)free);
- assert((unsigned long)free % getpagesize() == 0);
+ /* OK, expand metadata, do it again. */
+ set_page_state(pool, nextpage, TAKEN);
+ BUILD_ASSERT(FREE == 0);
+ memset((char *)pool + nextpage*getpagesize(), 0, getpagesize());
+ return alloc_metaspace(pool, poolsize, mh, bytes, type);
+ }
+
+ /* No metadata left at all? */
+ page = alloc_get_pages(pool, poolsize, div_up(bytes, getpagesize()), 1);
+ if (!page)
+ return NULL;
- pagenum = ((char *)free - (char *)pool - metalen) / getpagesize();
+ newmh = (struct metaheader *)((char *)pool + page * getpagesize());
+ BUILD_ASSERT(FREE == 0);
+ memset(newmh + 1, 0, getpagesize() - sizeof(*mh));
+
+ /* Sew it into linked list */
+ mh = first_mheader(pool,poolsize);
+ newmh->next = mh->next;
+ mh->next = pool_offset(pool, newmh);
+
+ return alloc_metaspace(pool, poolsize, newmh, bytes, type);
+}
+static void alloc_free_pages(void *pool, unsigned long pagenum)
+{
assert(get_page_state(pool, pagenum) == TAKEN_START);
set_page_state(pool, pagenum, FREE);
while (get_page_state(pool, ++pagenum) == TAKEN)
set_page_state(pool, pagenum, FREE);
}
-bool alloc_check(void *pool, unsigned long poolsize)
+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, 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++) {
+ unsigned long ret;
+ if (get_page_state(pool, i) != SPECIAL)
+ continue;
+
+ ret = sub_page_alloc(pool, i, size, align);
+ if (ret)
+ return ret;
+ }
+
+ /* Create new SUBPAGE page. */
+ i = alloc_get_pages(pool, poolsize, 1, 1);
+ if (i == 0)
+ return 0;
+
+ /* Get metadata for page. */
+ metadata = new_metadata(pool, poolsize, BITMAP_METALEN, BITMAP);
+ if (!metadata) {
+ alloc_free_pages(pool, i);
+ return 0;
+ }
+
+ /* Actually, this is a subpage page now. */
+ set_page_state(pool, i, SPECIAL);
+
+ /* Set metadata pointer for page. */
+ set_page_metadata(pool, i, metadata);
+
+ /* Do allocation like normal */
+ 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;
- enum page_state last_state = FREE;
+
+ 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)
+{
+ unsigned long i;
+ bool progress = false;
+
+ for (i = 0; i < poolsize/getpagesize(); i++) {
+ if (get_page_state(pool, i) != SPECIAL)
+ continue;
+
+ if (special_page_is_empty(pool, i)) {
+ clear_special_metadata(pool, i);
+ set_page_state(pool, i, FREE);
+ progress = true;
+ }
+ }
+ return progress;
+}
+
+/* Returns true if we cleaned any pages. */
+static bool clean_metadata(void *pool, unsigned long poolsize)
+{
+ struct metaheader *mh, *prev_mh = NULL;
+ bool progress = false;
+
+ for (mh = first_mheader(pool,poolsize); mh; mh = next_mheader(pool,mh)){
+ uint8_t *meta;
+ long i;
+ unsigned long metalen = get_metalen(pool, poolsize, mh);
+
+ meta = (uint8_t *)(mh + 1);
+ BUILD_ASSERT(FREE == 0);
+ for (i = metalen - 1; i > 0; i--)
+ if (meta[i] != 0)
+ break;
+
+ /* Completely empty? */
+ if (prev_mh && i == metalen) {
+ alloc_free_pages(pool,
+ pool_offset(pool, mh)/getpagesize());
+ prev_mh->next = mh->next;
+ mh = prev_mh;
+ progress = true;
+ } else {
+ uint8_t *p;
+
+ /* Some pages at end are free? */
+ for (p = (uint8_t *)(mh+1) + metalen - getpagesize();
+ p > meta + i;
+ p -= getpagesize()) {
+ set_page_state(pool,
+ pool_offset(pool, p)
+ / getpagesize(),
+ FREE);
+ progress = true;
+ }
+ }
+ }
+
+ return progress;
+}
+
+void *alloc_get(void *pool, unsigned long poolsize,
+ unsigned long size, unsigned long align)
+{
+ bool subpage_clean = false, metadata_clean = false;
+ unsigned long ret;
+
+ if (poolsize < MIN_SIZE)
+ return NULL;
+
+again:
+ /* Sub-page allocations have an overhead of ~12%. */
+ if (size + size/8 >= getpagesize() || align >= getpagesize()) {
+ unsigned long pages = div_up(size, getpagesize());
+
+ ret = alloc_get_pages(pool, poolsize, pages, align)
+ * getpagesize();
+ } else
+ ret = alloc_sub_page(pool, poolsize, size, align);
+
+ if (ret != 0)
+ return (char *)pool + ret;
+
+ /* Allocation failed: garbage collection. */
+ if (!subpage_clean) {
+ subpage_clean = true;
+ if (clean_empty_subpages(pool, poolsize))
+ goto again;
+ }
+
+ if (!metadata_clean) {
+ metadata_clean = true;
+ if (clean_metadata(pool, poolsize))
+ goto again;
+ }
+
+ /* FIXME: Compact metadata? */
+ return NULL;
+}
+
+static void bitmap_free(void *pool, unsigned long pagenum, unsigned long off,
+ uint8_t *metadata)
+{
+ assert(off % BITMAP_GRANULARITY == 0);
+
+ off /= BITMAP_GRANULARITY;
+
+ /* Offset by one because first bit is used for header. */
+ off++;
+
+ set_bit_pair(metadata, off++, FREE);
+ while (off < SUBPAGE_METAOFF / BITMAP_GRANULARITY
+ && get_bit_pair(metadata, off) == TAKEN)
+ 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;
+ struct metaheader *mh;
+
+ if (!free)
+ return;
+
+ assert(poolsize >= MIN_SIZE);
+
+ mh = first_mheader(pool, poolsize);
+ assert((char *)free >= (char *)(mh + 1));
+ assert((char *)pool + poolsize > (char *)free);
+
+ pagenum = pool_offset(pool, free) / getpagesize();
+
+ if (get_page_state(pool, pagenum) == SPECIAL)
+ subpage_free(pool, pagenum, free);
+ else {
+ assert((unsigned long)free % getpagesize() == 0);
+ alloc_free_pages(pool, pagenum);
+ }
+}
+
+static bool is_metadata_page(void *pool, unsigned long poolsize,
+ unsigned long page)
+{
+ struct metaheader *mh;
+
+ for (mh = first_mheader(pool,poolsize); mh; mh = next_mheader(pool,mh)){
+ unsigned long start, end;
+
+ start = pool_offset(pool, mh);
+ end = pool_offset(pool, (char *)(mh+1)
+ + get_metalen(pool, poolsize, mh));
+ if (page >= start/getpagesize() && page < end/getpagesize())
+ return true;
+ }
+ return false;
+}
+
+static bool check_bitmap_metadata(void *pool, unsigned long *mhoff)
+{
+ enum alloc_state last_state = FREE;
+ unsigned int i;
+
+ for (i = 0; i < SUBPAGE_METAOFF / BITMAP_GRANULARITY; i++) {
+ enum alloc_state state;
+
+ /* +1 because header is the first byte. */
+ state = get_bit_pair((uint8_t *)pool + *mhoff, i+1);
+ switch (state) {
+ case SPECIAL:
+ return false;
+ case TAKEN:
+ if (last_state == FREE)
+ return false;
+ break;
+ default:
+ break;
+ }
+ last_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;
+ struct metaheader *mh;
+ enum alloc_state last_state = FREE;
+ bool was_metadata = false;
if (poolsize < MIN_SIZE)
return true;
- metalen = metadata_length(pool, poolsize);
- for (i = 0; i < (poolsize - metalen) / getpagesize(); i++) {
- enum page_state state = get_page_state(pool, i);
+ if (get_page_state(pool, 0) != TAKEN_START)
+ return false;
+
+ /* First check metadata pages. */
+ /* Metadata pages will be marked TAKEN. */
+ for (mh = first_mheader(pool,poolsize); mh; mh = next_mheader(pool,mh)){
+ unsigned long start, end;
+
+ start = pool_offset(pool, mh);
+ if (start + sizeof(*mh) > poolsize)
+ return false;
+
+ end = pool_offset(pool, (char *)(mh+1)
+ + get_metalen(pool, poolsize, mh));
+ if (end > poolsize)
+ return false;
+
+ /* Non-first pages should start on a page boundary. */
+ if (mh != first_mheader(pool, poolsize)
+ && start % getpagesize() != 0)
+ return false;
+
+ /* It should end on a page boundary. */
+ if (end % getpagesize() != 0)
+ return false;
+ }
+
+ for (i = 0; i < poolsize / getpagesize(); i++) {
+ enum alloc_state state = get_page_state(pool, i);
+ bool is_metadata = is_metadata_page(pool, poolsize,i);
+
switch (state) {
case FREE:
+ /* metadata pages are never free. */
+ if (is_metadata)
+ return false;
case TAKEN_START:
break;
case TAKEN:
+ /* This should continue a previous block. */
if (last_state == FREE)
return false;
+ if (is_metadata != was_metadata)
+ return false;
break;
- default:
- return false;
+ case SPECIAL:
+ /* Check metadata pointer etc. */
+ if (!check_subpage(pool, poolsize, i))
+ return false;
}
last_state = state;
+ was_metadata = is_metadata;
}
return true;
}
+
+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;
+
+ if (poolsize < MIN_SIZE) {
+ fprintf(out, "Pool smaller than %u: no content\n", MIN_SIZE);
+ 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 = (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]);
+
+ /* One metadata page for every page of page bits. */
+ metadata_pages = div_up(pagebitlen, getpagesize());
+
+ /* Now do each metadata page. */
+ for (; mh; mh = next_mheader(pool,mh)) {
+ 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 * METADATA_PER_BYTE; i += len) {
+ switch (get_bit_pair(meta, i)) {
+ case FREE:
+ len = 1;
+ free++;
+ break;
+ case BITMAP:
+ /* Skip over this allocated part. */
+ len = BITMAP_METALEN * CHAR_BIT;
+ bitmapblocks++;
+ bitmaplen += len;
+ break;
+ case UNIFORM:
+ /* Skip over this part. */
+ len = decode_usize(meta + i/METADATA_PER_BYTE);
+ len = uniform_metalen(len) * METADATA_PER_BYTE;
+ uniformblocks++;
+ uniformlen += len;
+ break;
+ default:
+ assert(0);
+ }
+ }
+
+ 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, bitmapblocks, uniformblocks,
+ (bitmaplen + uniformlen) * 100
+ / (free + bitmaplen + uniformlen));
+ }
+
+ /* Account for total pages allocated. */
+ tot = (count[1] + count[2] - metadata_pages) * getpagesize();
+
+ fprintf(out, "Total metadata bytes = %lu\n",
+ metadata_pages * getpagesize());
+
+ /* Now do every subpage. */
+ for (i = 0; i < poolsize / getpagesize(); i++) {
+ uint8_t *meta;
+ 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);
+ type = get_bit_pair(meta, 0);
+
+ 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],
+ allocated * 100 / getpagesize());
+ tot += allocated;
+ }
+
+ /* This is optimistic, since we overalloc in several cases. */
+ fprintf(out, "Best possible allocation density = %lu%%\n",
+ tot * 100 / poolsize);
+}
projects / ccan / blobdiff