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Fix BITMAP_USE_TREE version of bitmap_ffu().

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This fixes an extent searching regression on 32-bit systems, caused by
the initial bitmap_ffu() implementation in
c8021d01f6 (Implement bitmap_ffu(), which
finds the first unset bit.), as first used in
5d33233a5e (Use a bitmap in extents_t to
speed up search.).
This commit is contained in:
Jason Evans 2017-03-24 22:46:56 -07:00
parent e6b074472e
commit 5e12223925
2 changed files with 48 additions and 5 deletions
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13
include/jemalloc/internal/bitmap_inlines.h
View File

@ -112,6 +112,19 @@ bitmap_ffu(const bitmap_t *bitmap, const bitmap_info_t *binfo, size_t min_bit) {
group &= group_mask; group &= group_mask;
} }
if (group == 0LU) { if (group == 0LU) {
/*
* If min_bit is not the first bit in its group, try
* again starting at the first bit of the next group.
* This will only recurse at most once, since on
* recursion, min_bit will be the first bit in its
* group.
*/
size_t ceil_min_bit = (min_bit +
BITMAP_GROUP_NBITS_MASK) & ~BITMAP_GROUP_NBITS_MASK;
if (ceil_min_bit != min_bit && ceil_min_bit <
binfo->nbits) {
return bitmap_ffu(bitmap, binfo, ceil_min_bit);
}
return binfo->nbits; return binfo->nbits;
} }
bit = (bit << LG_BITMAP_GROUP_NBITS) + (ffs_lu(group) - 1); bit = (bit << LG_BITMAP_GROUP_NBITS) + (ffs_lu(group) - 1);

40
test/unit/bitmap.c
View File

@ -273,7 +273,7 @@ TEST_BEGIN(test_bitmap_unset) {
TEST_END TEST_END
static void static void
test_bitmap_sfu_body(const bitmap_info_t *binfo, size_t nbits) { test_bitmap_xfu_body(const bitmap_info_t *binfo, size_t nbits) {
bitmap_t *bitmap = (bitmap_t *)malloc(bitmap_size(binfo)); bitmap_t *bitmap = (bitmap_t *)malloc(bitmap_size(binfo));
assert_ptr_not_null(bitmap, "Unexpected malloc() failure"); assert_ptr_not_null(bitmap, "Unexpected malloc() failure");
bitmap_init(bitmap, binfo, false); bitmap_init(bitmap, binfo, false);
@ -342,20 +342,50 @@ test_bitmap_sfu_body(const bitmap_info_t *binfo, size_t nbits) {
assert_zu_eq(bitmap_sfu(bitmap, binfo), nbits - 1, assert_zu_eq(bitmap_sfu(bitmap, binfo), nbits - 1,
"First unset bit should be the last bit"); "First unset bit should be the last bit");
assert_true(bitmap_full(bitmap, binfo), "All bits should be set"); assert_true(bitmap_full(bitmap, binfo), "All bits should be set");
/*
* Bubble a "usu" pattern through the bitmap and verify that
* bitmap_ffu() finds the correct bit for all five min_bit cases.
*/
if (nbits >= 3) {
for (size_t i = 0; i < nbits-2; i++) {
bitmap_unset(bitmap, binfo, i);
bitmap_unset(bitmap, binfo, i+2);
if (i > 0) {
assert_zu_eq(bitmap_ffu(bitmap, binfo, i-1), i,
"Unexpected first unset bit");
}
assert_zu_eq(bitmap_ffu(bitmap, binfo, i), i,
"Unexpected first unset bit");
assert_zu_eq(bitmap_ffu(bitmap, binfo, i+1), i+2,
"Unexpected first unset bit");
assert_zu_eq(bitmap_ffu(bitmap, binfo, i+2), i+2,
"Unexpected first unset bit");
if (i + 3 < nbits) {
assert_zu_eq(bitmap_ffu(bitmap, binfo, i+3),
nbits, "Unexpected first unset bit");
}
assert_zu_eq(bitmap_sfu(bitmap, binfo), i,
"Unexpected first unset bit");
assert_zu_eq(bitmap_sfu(bitmap, binfo), i+2,
"Unexpected first unset bit");
}
}
free(bitmap); free(bitmap);
} }
TEST_BEGIN(test_bitmap_sfu) { TEST_BEGIN(test_bitmap_xfu) {
size_t nbits; size_t nbits;
for (nbits = 1; nbits <= BITMAP_MAXBITS; nbits++) { for (nbits = 1; nbits <= BITMAP_MAXBITS; nbits++) {
bitmap_info_t binfo; bitmap_info_t binfo;
bitmap_info_init(&binfo, nbits); bitmap_info_init(&binfo, nbits);
test_bitmap_sfu_body(&binfo, nbits); test_bitmap_xfu_body(&binfo, nbits);
} }
#define NB(nbits) { \ #define NB(nbits) { \
bitmap_info_t binfo = BITMAP_INFO_INITIALIZER(nbits); \ bitmap_info_t binfo = BITMAP_INFO_INITIALIZER(nbits); \
test_bitmap_sfu_body(&binfo, nbits); \ test_bitmap_xfu_body(&binfo, nbits); \
} }
NBITS_TAB NBITS_TAB
#undef NB #undef NB
@ -370,5 +400,5 @@ main(void) {
test_bitmap_init, test_bitmap_init,
test_bitmap_set, test_bitmap_set,
test_bitmap_unset, test_bitmap_unset,
test_bitmap_sfu); test_bitmap_xfu);
} }