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qemu/tests/test-hbitmap.c

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add hierarchical bitmap data type and test cases HBitmaps provides an array of bits. The bits are stored as usual in an array of unsigned longs, but HBitmap is also optimized to provide fast iteration over set bits; going from one bit to the next is O(logB n) worst case, with B = sizeof(long) * CHAR_BIT: the result is low enough that the number of levels is in fact fixed. In order to do this, it stacks multiple bitmaps with progressively coarser granularity; in all levels except the last, bit N is set iff the N-th unsigned long is nonzero in the immediately next level. When iteration completes on the last level it can examine the 2nd-last level to quickly skip entire words, and even do so recursively to skip blocks of 64 words or powers thereof (32 on 32-bit machines). Given an index in the bitmap, it can be split in group of bits like this (for the 64-bit case): bits 0-57 => word in the last bitmap | bits 58-63 => bit in the word bits 0-51 => word in the 2nd-last bitmap | bits 52-57 => bit in the word bits 0-45 => word in the 3rd-last bitmap | bits 46-51 => bit in the word So it is easy to move up simply by shifting the index right by log2(BITS_PER_LONG) bits. To move down, you shift the index left similarly, and add the word index within the group. Iteration uses ffs (find first set bit) to find the next word to examine; this operation can be done in constant time in most current architectures. Setting or clearing a range of m bits on all levels, the work to perform is O(m + m/W + m/W^2 + ...), which is O(m) like on a regular bitmap. When iterating on a bitmap, each bit (on any level) is only visited once. Hence, The total cost of visiting a bitmap with m bits in it is the number of bits that are set in all bitmaps. Unless the bitmap is extremely sparse, this is also O(m + m/W + m/W^2 + ...), so the amortized cost of advancing from one bit to the next is usually constant. Reviewed-by: Laszlo Ersek <lersek@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2013-01-21 20:09:40 +04:00
/*
* Hierarchical bitmap unit-tests.
*
* Copyright (C) 2012 Red Hat Inc.
*
* Author: Paolo Bonzini <pbonzini@redhat.com>
*
* This work is licensed under the terms of the GNU GPL, version 2 or later.
* See the COPYING file in the top-level directory.
*/
#include <glib.h>
#include <stdarg.h>
#include "qemu/hbitmap.h"
#define LOG_BITS_PER_LONG (BITS_PER_LONG == 32 ? 5 : 6)
#define L1 BITS_PER_LONG
#define L2 (BITS_PER_LONG * L1)
#define L3 (BITS_PER_LONG * L2)
typedef struct TestHBitmapData {
HBitmap *hb;
unsigned long *bits;
size_t size;
int granularity;
} TestHBitmapData;
/* Check that the HBitmap and the shadow bitmap contain the same data,
* ignoring the same "first" bits.
*/
static void hbitmap_test_check(TestHBitmapData *data,
uint64_t first)
{
uint64_t count = 0;
size_t pos;
int bit;
HBitmapIter hbi;
int64_t i, next;
hbitmap_iter_init(&hbi, data->hb, first);
i = first;
for (;;) {
next = hbitmap_iter_next(&hbi);
if (next < 0) {
next = data->size;
}
while (i < next) {
pos = i >> LOG_BITS_PER_LONG;
bit = i & (BITS_PER_LONG - 1);
i++;
g_assert_cmpint(data->bits[pos] & (1UL << bit), ==, 0);
}
if (next == data->size) {
break;
}
pos = i >> LOG_BITS_PER_LONG;
bit = i & (BITS_PER_LONG - 1);
i++;
count++;
g_assert_cmpint(data->bits[pos] & (1UL << bit), !=, 0);
}
if (first == 0) {
g_assert_cmpint(count << data->granularity, ==, hbitmap_count(data->hb));
}
}
/* This is provided instead of a test setup function so that the sizes
are kept in the test functions (and not in main()) */
static void hbitmap_test_init(TestHBitmapData *data,
uint64_t size, int granularity)
{
size_t n;
data->hb = hbitmap_alloc(size, granularity);
n = (size + BITS_PER_LONG - 1) / BITS_PER_LONG;
if (n == 0) {
n = 1;
}
data->bits = g_new0(unsigned long, n);
data->size = size;
data->granularity = granularity;
hbitmap: add assertion on hbitmap_iter_init hbitmap_iter_init causes an out-of-bounds access when the "first" argument is or greater than or equal to the size of the bitmap. Forbid this with an assertion, and remove the failing testcase. Reported-by: Kevin Wolf <kwolf@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Reviewed-by: Laszlo Ersek <lersek@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2013-01-22 18:01:12 +04:00
if (size) {
hbitmap_test_check(data, 0);
}
add hierarchical bitmap data type and test cases HBitmaps provides an array of bits. The bits are stored as usual in an array of unsigned longs, but HBitmap is also optimized to provide fast iteration over set bits; going from one bit to the next is O(logB n) worst case, with B = sizeof(long) * CHAR_BIT: the result is low enough that the number of levels is in fact fixed. In order to do this, it stacks multiple bitmaps with progressively coarser granularity; in all levels except the last, bit N is set iff the N-th unsigned long is nonzero in the immediately next level. When iteration completes on the last level it can examine the 2nd-last level to quickly skip entire words, and even do so recursively to skip blocks of 64 words or powers thereof (32 on 32-bit machines). Given an index in the bitmap, it can be split in group of bits like this (for the 64-bit case): bits 0-57 => word in the last bitmap | bits 58-63 => bit in the word bits 0-51 => word in the 2nd-last bitmap | bits 52-57 => bit in the word bits 0-45 => word in the 3rd-last bitmap | bits 46-51 => bit in the word So it is easy to move up simply by shifting the index right by log2(BITS_PER_LONG) bits. To move down, you shift the index left similarly, and add the word index within the group. Iteration uses ffs (find first set bit) to find the next word to examine; this operation can be done in constant time in most current architectures. Setting or clearing a range of m bits on all levels, the work to perform is O(m + m/W + m/W^2 + ...), which is O(m) like on a regular bitmap. When iterating on a bitmap, each bit (on any level) is only visited once. Hence, The total cost of visiting a bitmap with m bits in it is the number of bits that are set in all bitmaps. Unless the bitmap is extremely sparse, this is also O(m + m/W + m/W^2 + ...), so the amortized cost of advancing from one bit to the next is usually constant. Reviewed-by: Laszlo Ersek <lersek@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2013-01-21 20:09:40 +04:00
}
static void hbitmap_test_teardown(TestHBitmapData *data,
const void *unused)
{
if (data->hb) {
hbitmap_free(data->hb);
data->hb = NULL;
}
if (data->bits) {
g_free(data->bits);
data->bits = NULL;
}
}
/* Set a range in the HBitmap and in the shadow "simple" bitmap.
* The two bitmaps are then tested against each other.
*/
static void hbitmap_test_set(TestHBitmapData *data,
uint64_t first, uint64_t count)
{
hbitmap_set(data->hb, first, count);
while (count-- != 0) {
size_t pos = first >> LOG_BITS_PER_LONG;
int bit = first & (BITS_PER_LONG - 1);
first++;
data->bits[pos] |= 1UL << bit;
}
if (data->granularity == 0) {
hbitmap_test_check(data, 0);
}
}
/* Reset a range in the HBitmap and in the shadow "simple" bitmap.
*/
static void hbitmap_test_reset(TestHBitmapData *data,
uint64_t first, uint64_t count)
{
hbitmap_reset(data->hb, first, count);
while (count-- != 0) {
size_t pos = first >> LOG_BITS_PER_LONG;
int bit = first & (BITS_PER_LONG - 1);
first++;
data->bits[pos] &= ~(1UL << bit);
}
if (data->granularity == 0) {
hbitmap_test_check(data, 0);
}
}
static void hbitmap_test_check_get(TestHBitmapData *data)
{
uint64_t count = 0;
uint64_t i;
for (i = 0; i < data->size; i++) {
size_t pos = i >> LOG_BITS_PER_LONG;
int bit = i & (BITS_PER_LONG - 1);
unsigned long val = data->bits[pos] & (1UL << bit);
count += hbitmap_get(data->hb, i);
g_assert_cmpint(hbitmap_get(data->hb, i), ==, val != 0);
}
g_assert_cmpint(count, ==, hbitmap_count(data->hb));
}
static void test_hbitmap_zero(TestHBitmapData *data,
const void *unused)
{
hbitmap_test_init(data, 0, 0);
}
static void test_hbitmap_unaligned(TestHBitmapData *data,
const void *unused)
{
hbitmap_test_init(data, L3 + 23, 0);
hbitmap_test_set(data, 0, 1);
hbitmap_test_set(data, L3 + 22, 1);
}
static void test_hbitmap_iter_empty(TestHBitmapData *data,
const void *unused)
{
hbitmap_test_init(data, L1, 0);
}
static void test_hbitmap_iter_partial(TestHBitmapData *data,
const void *unused)
{
hbitmap_test_init(data, L3, 0);
hbitmap_test_set(data, 0, L3);
hbitmap_test_check(data, 1);
hbitmap_test_check(data, L1 - 1);
hbitmap_test_check(data, L1);
hbitmap_test_check(data, L1 * 2 - 1);
hbitmap_test_check(data, L2 - 1);
hbitmap_test_check(data, L2);
hbitmap_test_check(data, L2 + 1);
hbitmap_test_check(data, L2 + L1);
hbitmap_test_check(data, L2 + L1 * 2 - 1);
hbitmap_test_check(data, L2 * 2 - 1);
hbitmap_test_check(data, L2 * 2);
hbitmap_test_check(data, L2 * 2 + 1);
hbitmap_test_check(data, L2 * 2 + L1);
hbitmap_test_check(data, L2 * 2 + L1 * 2 - 1);
hbitmap_test_check(data, L3 / 2);
}
static void test_hbitmap_set_all(TestHBitmapData *data,
const void *unused)
{
hbitmap_test_init(data, L3, 0);
hbitmap_test_set(data, 0, L3);
}
static void test_hbitmap_get_all(TestHBitmapData *data,
const void *unused)
{
hbitmap_test_init(data, L3, 0);
hbitmap_test_set(data, 0, L3);
hbitmap_test_check_get(data);
}
static void test_hbitmap_get_some(TestHBitmapData *data,
const void *unused)
{
hbitmap_test_init(data, 2 * L2, 0);
hbitmap_test_set(data, 10, 1);
hbitmap_test_check_get(data);
hbitmap_test_set(data, L1 - 1, 1);
hbitmap_test_check_get(data);
hbitmap_test_set(data, L1, 1);
hbitmap_test_check_get(data);
hbitmap_test_set(data, L2 - 1, 1);
hbitmap_test_check_get(data);
hbitmap_test_set(data, L2, 1);
hbitmap_test_check_get(data);
}
static void test_hbitmap_set_one(TestHBitmapData *data,
const void *unused)
{
hbitmap_test_init(data, 2 * L2, 0);
hbitmap_test_set(data, 10, 1);
hbitmap_test_set(data, L1 - 1, 1);
hbitmap_test_set(data, L1, 1);
hbitmap_test_set(data, L2 - 1, 1);
hbitmap_test_set(data, L2, 1);
}
static void test_hbitmap_set_two_elem(TestHBitmapData *data,
const void *unused)
{
hbitmap_test_init(data, 2 * L2, 0);
hbitmap_test_set(data, L1 - 1, 2);
hbitmap_test_set(data, L1 * 2 - 1, 4);
hbitmap_test_set(data, L1 * 4, L1 + 1);
hbitmap_test_set(data, L1 * 8 - 1, L1 + 1);
hbitmap_test_set(data, L2 - 1, 2);
hbitmap_test_set(data, L2 + L1 - 1, 8);
hbitmap_test_set(data, L2 + L1 * 4, L1 + 1);
hbitmap_test_set(data, L2 + L1 * 8 - 1, L1 + 1);
}
static void test_hbitmap_set(TestHBitmapData *data,
const void *unused)
{
hbitmap_test_init(data, L3 * 2, 0);
hbitmap_test_set(data, L1 - 1, L1 + 2);
hbitmap_test_set(data, L1 * 3 - 1, L1 + 2);
hbitmap_test_set(data, L1 * 5, L1 * 2 + 1);
hbitmap_test_set(data, L1 * 8 - 1, L1 * 2 + 1);
hbitmap_test_set(data, L2 - 1, L1 + 2);
hbitmap_test_set(data, L2 + L1 * 2 - 1, L1 + 2);
hbitmap_test_set(data, L2 + L1 * 4, L1 * 2 + 1);
hbitmap_test_set(data, L2 + L1 * 7 - 1, L1 * 2 + 1);
hbitmap_test_set(data, L2 * 2 - 1, L3 * 2 - L2 * 2);
}
static void test_hbitmap_set_twice(TestHBitmapData *data,
const void *unused)
{
hbitmap_test_init(data, L1 * 3, 0);
hbitmap_test_set(data, 0, L1 * 3);
hbitmap_test_set(data, L1, 1);
}
static void test_hbitmap_set_overlap(TestHBitmapData *data,
const void *unused)
{
hbitmap_test_init(data, L3 * 2, 0);
hbitmap_test_set(data, L1 - 1, L1 + 2);
hbitmap_test_set(data, L1 * 2 - 1, L1 * 2 + 2);
hbitmap_test_set(data, 0, L1 * 3);
hbitmap_test_set(data, L1 * 8 - 1, L2);
hbitmap_test_set(data, L2, L1);
hbitmap_test_set(data, L2 - L1 - 1, L1 * 8 + 2);
hbitmap_test_set(data, L2, L3 - L2 + 1);
hbitmap_test_set(data, L3 - L1, L1 * 3);
hbitmap_test_set(data, L3 - 1, 3);
hbitmap_test_set(data, L3 - 1, L2);
}
static void test_hbitmap_reset_empty(TestHBitmapData *data,
const void *unused)
{
hbitmap_test_init(data, L3, 0);
hbitmap_test_reset(data, 0, L3);
}
static void test_hbitmap_reset(TestHBitmapData *data,
const void *unused)
{
hbitmap_test_init(data, L3 * 2, 0);
hbitmap_test_set(data, L1 - 1, L1 + 2);
hbitmap_test_reset(data, L1 * 2 - 1, L1 * 2 + 2);
hbitmap_test_set(data, 0, L1 * 3);
hbitmap_test_reset(data, L1 * 8 - 1, L2);
hbitmap_test_set(data, L2, L1);
hbitmap_test_reset(data, L2 - L1 - 1, L1 * 8 + 2);
hbitmap_test_set(data, L2, L3 - L2 + 1);
hbitmap_test_reset(data, L3 - L1, L1 * 3);
hbitmap_test_set(data, L3 - 1, 3);
hbitmap_test_reset(data, L3 - 1, L2);
hbitmap_test_set(data, 0, L3 * 2);
hbitmap_test_reset(data, 0, L1);
hbitmap_test_reset(data, 0, L2);
hbitmap_test_reset(data, L3, L3);
hbitmap_test_set(data, L3 / 2, L3);
}
static void test_hbitmap_granularity(TestHBitmapData *data,
const void *unused)
{
/* Note that hbitmap_test_check has to be invoked manually in this test. */
hbitmap_test_init(data, L1, 1);
hbitmap_test_set(data, 0, 1);
g_assert_cmpint(hbitmap_count(data->hb), ==, 2);
hbitmap_test_check(data, 0);
hbitmap_test_set(data, 2, 1);
g_assert_cmpint(hbitmap_count(data->hb), ==, 4);
hbitmap_test_check(data, 0);
hbitmap_test_set(data, 0, 3);
g_assert_cmpint(hbitmap_count(data->hb), ==, 4);
hbitmap_test_reset(data, 0, 1);
g_assert_cmpint(hbitmap_count(data->hb), ==, 2);
}
static void test_hbitmap_iter_granularity(TestHBitmapData *data,
const void *unused)
{
HBitmapIter hbi;
/* Note that hbitmap_test_check has to be invoked manually in this test. */
hbitmap_test_init(data, 131072 << 7, 7);
hbitmap_iter_init(&hbi, data->hb, 0);
g_assert_cmpint(hbitmap_iter_next(&hbi), <, 0);
hbitmap_test_set(data, ((L2 + L1 + 1) << 7) + 8, 8);
hbitmap_iter_init(&hbi, data->hb, 0);
g_assert_cmpint(hbitmap_iter_next(&hbi), ==, (L2 + L1 + 1) << 7);
g_assert_cmpint(hbitmap_iter_next(&hbi), <, 0);
hbitmap_iter_init(&hbi, data->hb, (L2 + L1 + 2) << 7);
g_assert_cmpint(hbitmap_iter_next(&hbi), <, 0);
hbitmap_test_set(data, (131072 << 7) - 8, 8);
hbitmap_iter_init(&hbi, data->hb, 0);
g_assert_cmpint(hbitmap_iter_next(&hbi), ==, (L2 + L1 + 1) << 7);
g_assert_cmpint(hbitmap_iter_next(&hbi), ==, 131071 << 7);
g_assert_cmpint(hbitmap_iter_next(&hbi), <, 0);
hbitmap_iter_init(&hbi, data->hb, (L2 + L1 + 2) << 7);
g_assert_cmpint(hbitmap_iter_next(&hbi), ==, 131071 << 7);
g_assert_cmpint(hbitmap_iter_next(&hbi), <, 0);
}
static void hbitmap_test_add(const char *testpath,
void (*test_func)(TestHBitmapData *data, const void *user_data))
{
g_test_add(testpath, TestHBitmapData, NULL, NULL, test_func,
hbitmap_test_teardown);
}
int main(int argc, char **argv)
{
g_test_init(&argc, &argv, NULL);
hbitmap_test_add("/hbitmap/size/0", test_hbitmap_zero);
hbitmap_test_add("/hbitmap/size/unaligned", test_hbitmap_unaligned);
hbitmap_test_add("/hbitmap/iter/empty", test_hbitmap_iter_empty);
hbitmap_test_add("/hbitmap/iter/partial", test_hbitmap_iter_partial);
hbitmap_test_add("/hbitmap/iter/granularity", test_hbitmap_iter_granularity);
hbitmap_test_add("/hbitmap/get/all", test_hbitmap_get_all);
hbitmap_test_add("/hbitmap/get/some", test_hbitmap_get_some);
hbitmap_test_add("/hbitmap/set/all", test_hbitmap_set_all);
hbitmap_test_add("/hbitmap/set/one", test_hbitmap_set_one);
hbitmap_test_add("/hbitmap/set/two-elem", test_hbitmap_set_two_elem);
hbitmap_test_add("/hbitmap/set/general", test_hbitmap_set);
hbitmap_test_add("/hbitmap/set/twice", test_hbitmap_set_twice);
hbitmap_test_add("/hbitmap/set/overlap", test_hbitmap_set_overlap);
hbitmap_test_add("/hbitmap/reset/empty", test_hbitmap_reset_empty);
hbitmap_test_add("/hbitmap/reset/general", test_hbitmap_reset);
hbitmap_test_add("/hbitmap/granularity", test_hbitmap_granularity);
g_test_run();
return 0;
}
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