alloc: implement huge allocations

Inefficient scheme for allocations > 1/8192 of the pool size.

ccan/alloc/_info

@@ -100,6 +100,7 @@ int main(int argc, char *argv[])
 		return 1;
 
 	if (strcmp(argv[1], "depends") == 0) {
+		printf("ccan/alignof\n");
 		printf("ccan/build_assert\n");
 		printf("ccan/likely\n");
 		printf("ccan/short_types\n");

ccan/alloc/alloc.c

@@ -9,6 +9,7 @@
 #include "tiny.h"
 #include <ccan/build_assert/build_assert.h>
 #include <ccan/likely/likely.h>
+#include <ccan/alignof/alignof.h>
 #include <ccan/short_types/short_types.h>
 #include "config.h"
 
@@ -33,21 +34,12 @@
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  */
 
-#if 0 /* Until we have the tiny allocator working, go down to 64k */
-
 /* We divide the pool into this many large pages (nearest power of 2) */
 #define MAX_LARGE_PAGES (1024UL)
 
 /* 32 small pages == 1 large page. */
 #define BITS_FROM_SMALL_TO_LARGE_PAGE 5
 
-#else
-
-#define MAX_LARGE_PAGES (128UL)
-#define BITS_FROM_SMALL_TO_LARGE_PAGE 4
-
-#endif
-
 #define MAX_SMALL_PAGES (MAX_LARGE_PAGES << BITS_FROM_SMALL_TO_LARGE_PAGE)
 
 /* Smallest pool size for this scheme: 128-byte small pages.  That's
@@ -81,10 +73,18 @@ struct header {
 	u16 small_free_list;
 	u16 large_free_list;
 
+	/* List of huge allocs. */
+	unsigned long huge;
+
 	/* This is less defined: we have two buckets for each power of 2 */
 	struct bucket_state bs[1];
 };
 
+struct huge_alloc {
+	unsigned long next, prev;
+	unsigned long off, len;
+};
+
 struct page_header {
 	u16 next, prev;
 	/* FIXME: We can just count all-0 and all-1 used[] elements. */
@@ -215,6 +215,36 @@ static u16 pop_from_list(struct header *head,
 	return h;
 }
 
+static void add_to_huge_list(struct header *head, struct huge_alloc *ha)
+{
+	unsigned long h = head->huge;
+	unsigned long offset = (char *)ha - (char *)head;
+
+	ha->next = h;
+	if (h) {
+		struct huge_alloc *prev = (void *)((char *)head + h);
+		assert(prev->prev == 0);
+		prev->prev = offset;
+	}
+	head->huge = offset;
+	ha->prev = 0;
+}
+
+static void del_from_huge(struct header *head, struct huge_alloc *ha)
+{
+	/* Front of list? */
+	if (ha->prev == 0) {
+		head->huge = ha->next;
+	} else {
+		struct huge_alloc *prev = (void *)((char *)head + ha->prev);
+		prev->next = ha->next;
+	}
+	if (ha->next != 0) {
+		struct huge_alloc *next = (void *)((char *)head + ha->next);
+		next->prev = ha->prev;
+	}
+}
+
 static void add_small_page_to_freelist(struct header *head,
 				       struct page_header *ph,
 				       unsigned int sp_bits)
@@ -409,16 +439,11 @@ static bool all_empty(struct header *head,
 	return true;
 }
 
-static u16 get_large_page(struct header *head, unsigned long poolsize,
+static void recombine_small_pages(struct header *head, unsigned long poolsize,
 				  unsigned int sp_bits)
 {
-	unsigned int lp_bits, i, page;
-
-	lp_bits = sp_bits + BITS_FROM_SMALL_TO_LARGE_PAGE;
-
-	page = pop_from_list(head, &head->large_free_list, sp_bits);
-	if (likely(page))
-		return page;
+	unsigned long i;
+	unsigned int lp_bits = sp_bits + BITS_FROM_SMALL_TO_LARGE_PAGE;
 
 	/* Look for small pages to coalesce, after first large page. */
 	for (i = SMALL_PAGES_PER_LARGE_PAGE;
@@ -435,6 +460,20 @@ static u16 get_large_page(struct header *head, unsigned long poolsize,
 			add_large_page_to_freelist(head, ph, sp_bits);
 		}
 	}
+}
+
+static u16 get_large_page(struct header *head, unsigned long poolsize,
+			  unsigned int sp_bits)
+{
+	unsigned int lp_bits, page;
+
+	lp_bits = sp_bits + BITS_FROM_SMALL_TO_LARGE_PAGE;
+
+	page = pop_from_list(head, &head->large_free_list, sp_bits);
+	if (likely(page))
+		return page;
+
+	recombine_small_pages(head, poolsize, sp_bits);
 
 	return pop_from_list(head, &head->large_free_list, sp_bits);
 }
@@ -470,6 +509,232 @@ static u16 get_small_page(struct header *head, unsigned long poolsize,
 	return ret;
 }
 
+void where_is_page(struct header *head, struct page_header *where,
+		   unsigned int sp_bits)
+{
+	struct page_header *pg;
+	unsigned long off, bucket,
+		num_buckets = max_bucket(sp_bits + BITS_FROM_SMALL_TO_LARGE_PAGE);
+
+	for (off = head->small_free_list; off; off = pg->next) {
+		pg = from_pgnum(head, off, sp_bits);
+		if (pg == where) {
+			printf("It's in the small free list\n");
+			return;
+		}
+	}
+
+	for (off = head->large_free_list; off; off = pg->next) {
+		pg = from_pgnum(head, off, sp_bits);
+		if (pg == where) {
+			printf("It's in the large free list\n");
+			return;
+		}
+	}
+
+	for (bucket = 0; bucket < num_buckets; bucket++) {
+		for (off = head->bs[bucket].page_list; off; off = pg->next) {
+			pg = from_pgnum(head, off, sp_bits);
+			if (pg == where) {
+				printf("It's in %lu bucket page list\n", bucket);
+				return;
+			}
+		}
+
+		for (off = head->bs[bucket].full_list; off; off = pg->next) {
+			pg = from_pgnum(head, off, sp_bits);
+			if (pg == where) {
+				printf("It's in %lu bucket full list\n", bucket);
+				return;
+			}
+		}
+	}
+	printf("It's nowhere!\n");
+}
+
+static bool huge_allocated(struct header *head, unsigned long offset)
+{
+	unsigned long i;
+	struct huge_alloc *ha;
+
+	for (i = head->huge; i; i = ha->next) {
+		ha = (void *)((char *)head + i);
+		if (ha->off <= offset && ha->off + ha->len > offset)
+			return true;
+	}
+	return false;
+}
+
+/* They want something really big.  Aim for contiguous pages (slow). */
+static void *unlikely_func huge_alloc(void *pool, unsigned long poolsize,
+				      unsigned long size, unsigned long align)
+{
+	struct header *head = pool;
+	struct huge_alloc *ha;
+	unsigned long i, sp_bits, lp_bits, num, header_size;
+
+	sp_bits = small_page_bits(poolsize);
+	lp_bits = sp_bits + BITS_FROM_SMALL_TO_LARGE_PAGE;
+
+	/* Allocate tracking structure optimistically. */
+	ha = alloc_get(pool, poolsize, sizeof(*ha), ALIGNOF(*ha));
+	if (!ha)
+		return NULL;
+
+	/* First search for contiguous small pages... */
+	header_size = sizeof(*head) + sizeof(head->bs) * (max_bucket(lp_bits)-1);
+
+	num = 0;
+	for (i = (header_size + (1 << sp_bits) - 1) >> sp_bits;
+	     i << sp_bits < poolsize;
+	     i++) {
+		struct page_header *pg;
+		unsigned long off = (i << sp_bits);
+
+		/* Skip over large pages. */
+		if (test_bit(head->pagesize, i >> BITS_FROM_SMALL_TO_LARGE_PAGE)) {
+			i += (1 << BITS_FROM_SMALL_TO_LARGE_PAGE)-1;
+			continue;
+		}
+
+		/* Does this page meet alignment requirements? */
+		if (!num && off % align != 0)
+			continue;
+
+		/* FIXME: This makes us O(n^2). */
+		if (huge_allocated(head, off)) {
+			num = 0;
+			continue;
+		}
+
+		pg = (struct page_header *)((char *)head + off);
+		if (pg->elements_used) {
+			num = 0;
+			continue;
+		}
+
+		num++;
+		if (num << sp_bits >= size) {
+			unsigned long pgnum;
+
+			/* Remove from free list. */
+			for (pgnum = i; pgnum > i - num; pgnum--) {
+				pg = from_pgnum(head, pgnum, sp_bits);
+				del_from_list(head,
+					      &head->small_free_list,
+					      pg, sp_bits);
+			}
+			ha->off = (i - num + 1) << sp_bits;
+			ha->len = num << sp_bits;
+			goto done;
+		}
+	}
+
+	/* Now search for large pages... */
+	recombine_small_pages(head, poolsize, sp_bits);
+
+	num = 0;
+	for (i = (header_size + (1 << lp_bits) - 1) >> lp_bits;
+	     (i << lp_bits) < poolsize; i++) {
+		struct page_header *pg;
+		unsigned long off = (i << lp_bits);
+
+		/* Ignore small pages. */
+		if (!test_bit(head->pagesize, i))
+			continue;
+
+		/* Does this page meet alignment requirements? */
+		if (!num && off % align != 0)
+			continue;
+
+		/* FIXME: This makes us O(n^2). */
+		if (huge_allocated(head, off)) {
+			num = 0;
+			continue;
+		}
+
+		pg = (struct page_header *)((char *)head + off);
+		if (pg->elements_used) {
+			num = 0;
+			continue;
+		}
+
+		num++;
+		if (num << lp_bits >= size) {
+			unsigned long pgnum;
+
+			/* Remove from free list. */
+			for (pgnum = i; pgnum > i - num; pgnum--) {
+				pg = from_pgnum(head, pgnum, lp_bits);
+				del_from_list(head,
+					      &head->large_free_list,
+					      pg, sp_bits);
+			}
+			ha->off = (i - num + 1) << lp_bits;
+			ha->len = num << lp_bits;
+			goto done;
+		}
+	}
+
+	/* Unable to satisfy: free huge alloc structure. */
+	alloc_free(pool, poolsize, ha);
+	return NULL;
+
+done:
+	add_to_huge_list(pool, ha);
+	return (char *)pool + ha->off;
+}
+
+static void unlikely_func huge_free(struct header *head,
+				    unsigned long poolsize, void *free)
+{
+	unsigned long i, off, pgnum, free_off = (char *)free - (char *)head;
+	unsigned int sp_bits, lp_bits;
+	struct huge_alloc *ha;
+
+	for (i = head->huge; i; i = ha->next) {
+		ha = (void *)((char *)head + i);
+		if (free_off == ha->off)
+			break;
+	}
+	assert(i);
+
+	/* Free up all the pages, delete and free ha */
+	sp_bits = small_page_bits(poolsize);
+	lp_bits = sp_bits + BITS_FROM_SMALL_TO_LARGE_PAGE;
+	pgnum = free_off >> sp_bits;
+
+	if (test_bit(head->pagesize, pgnum >> BITS_FROM_SMALL_TO_LARGE_PAGE)) {
+		for (off = ha->off; off < ha->off + ha->len; off += 1 << lp_bits) {
+			add_large_page_to_freelist(head,
+						   (void *)((char *)head + off),
+						   sp_bits);
+		}
+	} else {
+		for (off = ha->off; off < ha->off + ha->len; off += 1 << sp_bits) {
+			add_small_page_to_freelist(head,
+						   (void *)((char *)head + off),
+						   sp_bits);
+		}
+	}
+	del_from_huge(head, ha);
+	alloc_free(head, poolsize, ha);
+}
+
+static unsigned long unlikely_func huge_size(struct header *head, void *p)
+{
+	unsigned long i, off = (char *)p - (char *)head;
+	struct huge_alloc *ha;
+
+	for (i = head->huge; i; i = ha->next) {
+		ha = (void *)((char *)head + i);
+		if (off == ha->off) {
+			return ha->len;
+		}
+	}
+	abort();
+}
+
 void *alloc_get(void *pool, unsigned long poolsize,
 		unsigned long size, unsigned long align)
 {
@@ -492,8 +757,7 @@ void *alloc_get(void *pool, unsigned long poolsize,
 	sp_bits = small_page_bits(poolsize);
 
 	if (bucket >= max_bucket(sp_bits + BITS_FROM_SMALL_TO_LARGE_PAGE)) {
-		/* FIXME: huge alloc. */
-		return NULL;
+		return huge_alloc(pool, poolsize, size, align);
 	}
 
 	bs = &head->bs[bucket];
@@ -560,6 +824,11 @@ void alloc_free(void *pool, unsigned long poolsize, void *free)
 
 	/* Step back to page header. */
 	ph = from_pgnum(head, pgnum, sp_bits);
+	if ((void *)ph == free) {
+		huge_free(head, poolsize, free);
+		return;
+	}
+
 	bs = &head->bs[ph->bucket];
 	pgoffset = offset - (pgnum << sp_bits)
 		- page_header_size(ph->bucket / INTER_BUCKET_SPACE,
@@ -605,6 +874,9 @@ unsigned long alloc_size(void *pool, unsigned long poolsize, void *p)
 
 	/* Step back to page header. */
 	ph = from_pgnum(head, pgnum, sp_bits);
+	if ((void *)ph == p)
+		return huge_size(head, p);
+
 	return bucket_to_size(ph->bucket);
 }
 
@@ -752,6 +1024,7 @@ bool alloc_check(void *pool, unsigned long poolsize)
 	struct header *head = pool;
 	unsigned long prev, i, lp_bits, sp_bits, header_size, num_buckets;
 	struct page_header *ph;
+	struct huge_alloc *ha;
 	unsigned long pages[MAX_SMALL_PAGES / BITS_PER_LONG] = { 0 };
 
 	if (poolsize < MIN_USEFUL_SIZE)
@@ -819,6 +1092,46 @@ bool alloc_check(void *pool, unsigned long poolsize)
 			return false;
 	}
 
+	/* Check the huge alloc list. */
+	prev = 0;
+	for (i = head->huge; i; i = ha->next) {
+		unsigned long pgbits, j;
+
+		/* Bad pointer? */
+		if (i >= poolsize || i + sizeof(*ha) > poolsize)
+			return check_fail();
+		ha = (void *)((char *)head + i);
+
+		/* Check contents of ha. */
+		if (ha->off > poolsize || ha->off + ha->len > poolsize)
+			return check_fail();
+
+		/* Large or small page? */
+		pgbits = test_bit(head->pagesize, ha->off >> lp_bits)
+			? lp_bits : sp_bits;
+
+		/* Not page boundary? */
+		if ((ha->off % (1UL << pgbits)) != 0)
+			return check_fail();
+
+		/* Not page length? */
+		if ((ha->len % (1UL << pgbits)) != 0)
+			return check_fail();
+
+		/* Linked list corrupt? */
+		if (ha->prev != prev)
+			return check_fail();
+
+		for (j = ha->off; j < ha->off + ha->len; j += (1 << sp_bits)) {
+			/* Already seen this page? */
+			if (test_bit(pages, j >> sp_bits))
+				return check_fail();
+			set_bit(pages, j >> sp_bits);
+		}
+
+		prev = i;
+	}
+		
 	/* Make sure every page accounted for. */
 	for (i = 0; i < poolsize >> sp_bits; i++) {
 		if (!test_bit(pages, i))
@@ -945,7 +1258,7 @@ void alloc_visualize(FILE *out, void *pool, unsigned long poolsize)
 		count, i, count ? 100.0 * count / i : 0.0);
 
 	/* Total small pages. */
-	i = (poolsize >> lp_bits) - i;
+	i = ((poolsize >> lp_bits) - i) << BITS_FROM_SMALL_TO_LARGE_PAGE;
 	/* Used pages */
 	count = i - count_list(head, head->small_free_list, sp_bits, NULL);
 	fprintf(out, "%lu/%lu small pages used (%.3g%%)\n",

ccan/alloc/test/run-testsize.c

@@ -27,7 +27,7 @@ static bool sizes_ok(void *mem, unsigned long poolsize, void *p[], unsigned num)
 
 static void test_pool(unsigned long pool_size)
 {
-	unsigned int i, j, num;
+	unsigned int i, num;
 	void *mem;
 	void **p;
 	bool flip = false;
@@ -50,17 +50,15 @@ static void test_pool(unsigned long pool_size)
 	ok1(sizes_ok(mem, pool_size, p, num));
 
 	/* Free every second one. */
-	for (i = j = 0; i < num; i = i * 3 / 2 + 1) {
+	for (i = 0; i < num; i = i * 3 / 2 + 1) {
 		flip = !flip;
 		if (flip) {
-			/* Compact. */
-			p[j++] = p[i];
 			invert_bytes(p[i], alloc_size(mem,pool_size,p[i]));
 			continue;
 		}
 		alloc_free(mem, pool_size, p[i]);
+		p[i] = NULL;
 	}
-	num /= 2;
 	ok1(alloc_check(mem, pool_size));
 	ok1(sizes_ok(mem, pool_size, p, num));
 	free(p);

ccan/alloc/test/run.c

@@ -48,12 +48,9 @@ static void test(unsigned int pool_size)
 	void *mem;
 	unsigned int i, num, max_size;
 	void **p = calloc(pool_size, sizeof(*p));
-	/* FIXME: Should be pool_size! */
-	unsigned alloc_limit = (pool_size / MAX_LARGE_PAGES) >> MAX_PAGE_OBJECT_ORDER;
+	unsigned alloc_limit = pool_size / 2;
 
-	/* FIXME: Needs to be page aligned for now. */
-	if (posix_memalign(&mem, pool_size, pool_size) != 0)
-		errx(1, "Failed allocating aligned memory"); 
+	mem = malloc(pool_size);
 
 	/* Small pool, all allocs fail, even 0-length. */
 	alloc_init(mem, 0);
@@ -136,7 +133,7 @@ static void test(unsigned int pool_size)
 	for (i = 0; (1 << i) < alloc_limit; i++) {
 		p[i] = alloc_get(mem, pool_size, i, 1 << i);
 		ok1(p[i]);
-		ok1(((unsigned long)p[i] % (1 << i)) == 0);
+		ok1(((char *)p[i] - (char *)mem) % (1 << i) == 0);
 		ok1(alloc_check(mem, pool_size));
 		ok1(alloc_size(mem, pool_size, p[i]) >= i);
 	}
@@ -150,8 +147,9 @@ static void test(unsigned int pool_size)
 	for (i = 0; (1 << i) < alloc_limit; i++) {
 		p[0] = alloc_get(mem, pool_size, 1, 1 << i);
 		ok1(p[0]);
+		ok1(((char *)p[0] - (char *)mem) % (1 << i) == 0);
 		ok1(alloc_check(mem, pool_size));
-		ok1(alloc_size(mem, pool_size, p[i]) >= 1);
+		ok1(alloc_size(mem, pool_size, p[0]) >= 1);
 		alloc_free(mem, pool_size, p[0]);
 		ok1(alloc_check(mem, pool_size));
 	}
@@ -166,7 +164,7 @@ static void test(unsigned int pool_size)
 
 int main(int argc, char *argv[])
 {
-	plan_tests(112 + 92);
+	plan_tests(480);
 
 	/* Large test. */
 	test(MIN_USEFUL_SIZE * 2);