Add memory utilization analytics to mallctl

The analytics tool is put under experimental.utilization namespace in
mallctl.  Input is one pointer or an array of pointers and the output
is a list of memory utilization statistics.
This commit is contained in:
Yinan Zhang 2019-03-15 11:01:45 -07:00 committed by Qi Wang
parent b0b3e49a54
commit 9aab3f2be0
6 changed files with 526 additions and 5 deletions

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@ -74,4 +74,10 @@ bool extent_merge_wrapper(tsdn_t *tsdn, arena_t *arena,
bool extent_boot(void);
void extent_util_stats_get(tsdn_t *tsdn, const void *ptr,
size_t *nfree, size_t *nregs, size_t *size);
void extent_util_stats_verbose_get(tsdn_t *tsdn, const void *ptr,
size_t *nfree, size_t *nregs, size_t *size,
size_t *bin_nfree, size_t *bin_nregs, void **slabcur_addr);
#endif /* JEMALLOC_INTERNAL_EXTENT_EXTERNS_H */

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@ -228,4 +228,25 @@ struct extents_s {
bool delay_coalesce;
};
/*
* The following two structs are for experimental purposes. See
* experimental_utilization_query_ctl and
* experimental_utilization_batch_query_ctl in src/ctl.c.
*/
struct extent_util_stats_s {
size_t nfree;
size_t nregs;
size_t size;
};
struct extent_util_stats_verbose_s {
void *slabcur_addr;
size_t nfree;
size_t nregs;
size_t size;
size_t bin_nfree;
size_t bin_nregs;
};
#endif /* JEMALLOC_INTERNAL_EXTENT_STRUCTS_H */

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@ -4,6 +4,9 @@
typedef struct extent_s extent_t;
typedef struct extents_s extents_t;
typedef struct extent_util_stats_s extent_util_stats_t;
typedef struct extent_util_stats_verbose_s extent_util_stats_verbose_t;
#define EXTENT_HOOKS_INITIALIZER NULL
/*

232
src/ctl.c
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@ -216,6 +216,8 @@ CTL_PROTO(stats_mapped)
CTL_PROTO(stats_retained)
CTL_PROTO(experimental_hooks_install)
CTL_PROTO(experimental_hooks_remove)
CTL_PROTO(experimental_utilization_query)
CTL_PROTO(experimental_utilization_batch_query)
#define MUTEX_STATS_CTL_PROTO_GEN(n) \
CTL_PROTO(stats_##n##_num_ops) \
@ -574,11 +576,17 @@ static const ctl_named_node_t stats_node[] = {
static const ctl_named_node_t hooks_node[] = {
{NAME("install"), CTL(experimental_hooks_install)},
{NAME("remove"), CTL(experimental_hooks_remove)},
{NAME("remove"), CTL(experimental_hooks_remove)}
};
static const ctl_named_node_t utilization_node[] = {
{NAME("query"), CTL(experimental_utilization_query)},
{NAME("batch_query"), CTL(experimental_utilization_batch_query)}
};
static const ctl_named_node_t experimental_node[] = {
{NAME("hooks"), CHILD(named, hooks)}
{NAME("hooks"), CHILD(named, hooks)},
{NAME("utilization"), CHILD(named, utilization)}
};
static const ctl_named_node_t root_node[] = {
@ -3083,3 +3091,223 @@ experimental_hooks_remove_ctl(tsd_t *tsd, const size_t *mib, size_t miblen,
label_return:
return ret;
}
/*
* Output six memory utilization entries for an input pointer, the first one of
* type (void *) and the remaining five of type size_t, describing the following
* (in the same order):
*
* (a) memory address of the extent a potential reallocation would go into,
* == the five fields below describe about the extent the pointer resides in ==
* (b) number of free regions in the extent,
* (c) number of regions in the extent,
* (d) size of the extent in terms of bytes,
* (e) total number of free regions in the bin the extent belongs to, and
* (f) total number of regions in the bin the extent belongs to.
*
* Note that "(e)" and "(f)" are only available when stats are enabled;
* otherwise both are set zero.
*
* This API is mainly intended for small class allocations, where extents are
* used as slab.
*
* In case of large class allocations, "(a)" will be NULL, and "(e)" and "(f)"
* will be zero. The other three fields will be properly set though the values
* are trivial: "(b)" will be 0, "(c)" will be 1, and "(d)" will be the usable
* size.
*
* The input pointer and size are respectively passed in by newp and newlen,
* and the output fields and size are respectively oldp and *oldlenp.
*
* It can be beneficial to define the following macros to make it easier to
* access the output:
*
* #define SLABCUR_READ(out) (*(void **)out)
* #define COUNTS(out) ((size_t *)((void **)out + 1))
* #define NFREE_READ(out) COUNTS(out)[0]
* #define NREGS_READ(out) COUNTS(out)[1]
* #define SIZE_READ(out) COUNTS(out)[2]
* #define BIN_NFREE_READ(out) COUNTS(out)[3]
* #define BIN_NREGS_READ(out) COUNTS(out)[4]
*
* and then write e.g. NFREE_READ(oldp) to fetch the output. See the unit test
* test_utilization_query in test/unit/mallctl.c for an example.
*
* For a typical defragmentation workflow making use of this API for
* understanding the fragmentation level, please refer to the comment for
* experimental_utilization_batch_query_ctl.
*
* It's up to the application how to determine the significance of
* fragmentation relying on the outputs returned. Possible choices are:
*
* (a) if extent utilization ratio is below certain threshold,
* (b) if extent memory consumption is above certain threshold,
* (c) if extent utilization ratio is significantly below bin utilization ratio,
* (d) if input pointer deviates a lot from potential reallocation address, or
* (e) some selection/combination of the above.
*
* The caller needs to make sure that the input/output arguments are valid,
* in particular, that the size of the output is correct, i.e.:
*
* *oldlenp = sizeof(void *) + sizeof(size_t) * 5
*
* Otherwise, the function immediately returns EINVAL without touching anything.
*
* In the rare case where there's no associated extent found for the input
* pointer, the function zeros out all output fields and return. Please refer
* to the comment for experimental_utilization_batch_query_ctl to understand the
* motivation from C++.
*/
static int
experimental_utilization_query_ctl(tsd_t *tsd, const size_t *mib,
size_t miblen, void *oldp, size_t *oldlenp, void *newp, size_t newlen) {
int ret;
assert(sizeof(extent_util_stats_verbose_t)
== sizeof(void *) + sizeof(size_t) * 5);
if (oldp == NULL || oldlenp == NULL
|| *oldlenp != sizeof(extent_util_stats_verbose_t)
|| newp == NULL) {
ret = EINVAL;
goto label_return;
}
void *ptr = NULL;
WRITE(ptr, void *);
extent_util_stats_verbose_t *util_stats
= (extent_util_stats_verbose_t *)oldp;
extent_util_stats_verbose_get(tsd_tsdn(tsd), ptr,
&util_stats->nfree, &util_stats->nregs, &util_stats->size,
&util_stats->bin_nfree, &util_stats->bin_nregs,
&util_stats->slabcur_addr);
ret = 0;
label_return:
return ret;
}
/*
* Given an input array of pointers, output three memory utilization entries of
* type size_t for each input pointer about the extent it resides in:
*
* (a) number of free regions in the extent,
* (b) number of regions in the extent, and
* (c) size of the extent in terms of bytes.
*
* This API is mainly intended for small class allocations, where extents are
* used as slab. In case of large class allocations, the outputs are trivial:
* "(a)" will be 0, "(b)" will be 1, and "(c)" will be the usable size.
*
* Note that multiple input pointers may reside on a same extent so the output
* fields may contain duplicates.
*
* The format of the input/output looks like:
*
* input[0]: 1st_pointer_to_query | output[0]: 1st_extent_n_free_regions
* | output[1]: 1st_extent_n_regions
* | output[2]: 1st_extent_size
* input[1]: 2nd_pointer_to_query | output[3]: 2nd_extent_n_free_regions
* | output[4]: 2nd_extent_n_regions
* | output[5]: 2nd_extent_size
* ... | ...
*
* The input array and size are respectively passed in by newp and newlen, and
* the output array and size are respectively oldp and *oldlenp.
*
* It can be beneficial to define the following macros to make it easier to
* access the output:
*
* #define NFREE_READ(out, i) out[(i) * 3]
* #define NREGS_READ(out, i) out[(i) * 3 + 1]
* #define SIZE_READ(out, i) out[(i) * 3 + 2]
*
* and then write e.g. NFREE_READ(oldp, i) to fetch the output. See the unit
* test test_utilization_batch in test/unit/mallctl.c for a concrete example.
*
* A typical workflow would be composed of the following steps:
*
* (1) flush tcache: mallctl("thread.tcache.flush", ...)
* (2) initialize input array of pointers to query fragmentation
* (3) allocate output array to hold utilization statistics
* (4) query utilization: mallctl("experimental.utilization.batch_query", ...)
* (5) (optional) decide if it's worthwhile to defragment; otherwise stop here
* (6) disable tcache: mallctl("thread.tcache.enabled", ...)
* (7) defragment allocations with significant fragmentation, e.g.:
* for each allocation {
* if it's fragmented {
* malloc(...);
* memcpy(...);
* free(...);
* }
* }
* (8) enable tcache: mallctl("thread.tcache.enabled", ...)
*
* The application can determine the significance of fragmentation themselves
* relying on the statistics returned, both at the overall level i.e. step "(5)"
* and at individual allocation level i.e. within step "(7)". Possible choices
* are:
*
* (a) whether memory utilization ratio is below certain threshold,
* (b) whether memory consumption is above certain threshold, or
* (c) some combination of the two.
*
* The caller needs to make sure that the input/output arrays are valid and
* their sizes are proper as well as matched, meaning:
*
* (a) newlen = n_pointers * sizeof(const void *)
* (b) *oldlenp = n_pointers * sizeof(size_t) * 3
* (c) n_pointers > 0
*
* Otherwise, the function immediately returns EINVAL without touching anything.
*
* In the rare case where there's no associated extent found for some pointers,
* rather than immediately terminating the computation and raising an error,
* the function simply zeros out the corresponding output fields and continues
* the computation until all input pointers are handled. The motivations of
* such a design are as follows:
*
* (a) The function always either processes nothing or processes everything, and
* never leaves the output half touched and half untouched.
*
* (b) It facilitates usage needs especially common in C++. A vast variety of
* C++ objects are instantiated with multiple dynamic memory allocations. For
* example, std::string and std::vector typically use at least two allocations,
* one for the metadata and one for the actual content. Other types may use
* even more allocations. When inquiring about utilization statistics, the
* caller often wants to examine into all such allocations, especially internal
* one(s), rather than just the topmost one. The issue comes when some
* implementations do certain optimizations to reduce/aggregate some internal
* allocations, e.g. putting short strings directly into the metadata, and such
* decisions are not known to the caller. Therefore, we permit pointers to
* memory usages that may not be returned by previous malloc calls, and we
* provide the caller a convenient way to identify such cases.
*/
static int
experimental_utilization_batch_query_ctl(tsd_t *tsd, const size_t *mib,
size_t miblen, void *oldp, size_t *oldlenp, void *newp, size_t newlen) {
int ret;
assert(sizeof(extent_util_stats_t) == sizeof(size_t) * 3);
const size_t len = newlen / sizeof(const void *);
if (oldp == NULL || oldlenp == NULL || newp == NULL || newlen == 0
|| newlen != len * sizeof(const void *)
|| *oldlenp != len * sizeof(extent_util_stats_t)) {
ret = EINVAL;
goto label_return;
}
void **ptrs = (void **)newp;
extent_util_stats_t *util_stats = (extent_util_stats_t *)oldp;
size_t i;
for (i = 0; i < len; ++i) {
extent_util_stats_get(tsd_tsdn(tsd), ptrs[i],
&util_stats[i].nfree, &util_stats[i].nregs,
&util_stats[i].size);
}
ret = 0;
label_return:
return ret;
}

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@ -2280,3 +2280,72 @@ extent_boot(void) {
return false;
}
void
extent_util_stats_get(tsdn_t *tsdn, const void *ptr,
size_t *nfree, size_t *nregs, size_t *size) {
assert(ptr != NULL && nfree != NULL && nregs != NULL && size != NULL);
const extent_t *extent = iealloc(tsdn, ptr);
if (unlikely(extent == NULL)) {
*nfree = *nregs = *size = 0;
return;
}
*size = extent_size_get(extent);
if (!extent_slab_get(extent)) {
*nfree = 0;
*nregs = 1;
} else {
*nfree = extent_nfree_get(extent);
*nregs = bin_infos[extent_szind_get(extent)].nregs;
assert(*nfree <= *nregs);
assert(*nfree * extent_usize_get(extent) <= *size);
}
}
void
extent_util_stats_verbose_get(tsdn_t *tsdn, const void *ptr,
size_t *nfree, size_t *nregs, size_t *size,
size_t *bin_nfree, size_t *bin_nregs, void **slabcur_addr) {
assert(ptr != NULL && nfree != NULL && nregs != NULL && size != NULL
&& bin_nfree != NULL && bin_nregs != NULL && slabcur_addr != NULL);
const extent_t *extent = iealloc(tsdn, ptr);
if (unlikely(extent == NULL)) {
*nfree = *nregs = *size = *bin_nfree = *bin_nregs = 0;
*slabcur_addr = NULL;
return;
}
*size = extent_size_get(extent);
if (!extent_slab_get(extent)) {
*nfree = *bin_nfree = *bin_nregs = 0;
*nregs = 1;
*slabcur_addr = NULL;
return;
}
*nfree = extent_nfree_get(extent);
const szind_t szind = extent_szind_get(extent);
*nregs = bin_infos[szind].nregs;
assert(*nfree <= *nregs);
assert(*nfree * extent_usize_get(extent) <= *size);
const arena_t *arena = extent_arena_get(extent);
assert(arena != NULL);
const unsigned binshard = extent_binshard_get(extent);
bin_t *bin = &arena->bins[szind].bin_shards[binshard];
malloc_mutex_lock(tsdn, &bin->lock);
if (config_stats) {
*bin_nregs = *nregs * bin->stats.curslabs;
assert(*bin_nregs >= bin->stats.curregs);
*bin_nfree = *bin_nregs - bin->stats.curregs;
} else {
*bin_nfree = *bin_nregs = 0;
}
*slabcur_addr = extent_addr_get(bin->slabcur);
assert(*slabcur_addr != NULL);
malloc_mutex_unlock(tsdn, &bin->lock);
}

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@ -853,6 +853,198 @@ TEST_BEGIN(test_hooks_exhaustion) {
}
TEST_END
#define TEST_UTIL_EINVAL(node, a, b, c, d, why_inval) do { \
assert_d_eq(mallctl("experimental.utilization." node, \
a, b, c, d), EINVAL, "Should fail when " why_inval); \
assert_zu_eq(out_sz, out_sz_ref, \
"Output size touched when given invalid arguments"); \
assert_d_eq(memcmp(out, out_ref, out_sz_ref), 0, \
"Output content touched when given invalid arguments"); \
} while (0)
#define TEST_UTIL_VALID(node) do { \
assert_d_eq(mallctl("experimental.utilization." node, \
out, &out_sz, in, in_sz), 0, \
"Should return 0 on correct arguments"); \
assert_zu_eq(out_sz, out_sz_ref, "incorrect output size"); \
assert_d_ne(memcmp(out, out_ref, out_sz_ref), 0, \
"Output content should be changed"); \
} while (0)
TEST_BEGIN(test_utilization_query) {
void *p = mallocx(1, 0);
void **in = &p;
size_t in_sz = sizeof(const void *);
size_t out_sz = sizeof(void *) + sizeof(size_t) * 5;
void *out = mallocx(out_sz, 0);
void *out_ref = mallocx(out_sz, 0);
size_t out_sz_ref = out_sz;
assert_ptr_not_null(p, "test pointer allocation failed");
assert_ptr_not_null(out, "test output allocation failed");
assert_ptr_not_null(out_ref, "test reference output allocation failed");
#define SLABCUR_READ(out) (*(void **)out)
#define COUNTS(out) ((size_t *)((void **)out + 1))
#define NFREE_READ(out) COUNTS(out)[0]
#define NREGS_READ(out) COUNTS(out)[1]
#define SIZE_READ(out) COUNTS(out)[2]
#define BIN_NFREE_READ(out) COUNTS(out)[3]
#define BIN_NREGS_READ(out) COUNTS(out)[4]
SLABCUR_READ(out) = NULL;
NFREE_READ(out) = NREGS_READ(out) = SIZE_READ(out) = -1;
BIN_NFREE_READ(out) = BIN_NREGS_READ(out) = -1;
memcpy(out_ref, out, out_sz);
/* Test invalid argument(s) errors */
#define TEST_UTIL_QUERY_EINVAL(a, b, c, d, why_inval) \
TEST_UTIL_EINVAL("query", a, b, c, d, why_inval)
TEST_UTIL_QUERY_EINVAL(NULL, &out_sz, in, in_sz, "old is NULL");
TEST_UTIL_QUERY_EINVAL(out, NULL, in, in_sz, "oldlenp is NULL");
TEST_UTIL_QUERY_EINVAL(out, &out_sz, NULL, in_sz, "newp is NULL");
TEST_UTIL_QUERY_EINVAL(out, &out_sz, in, 0, "newlen is zero");
in_sz -= 1;
TEST_UTIL_QUERY_EINVAL(out, &out_sz, in, in_sz, "invalid newlen");
in_sz += 1;
out_sz_ref = out_sz -= 2 * sizeof(size_t);
TEST_UTIL_QUERY_EINVAL(out, &out_sz, in, in_sz, "invalid *oldlenp");
out_sz_ref = out_sz += 2 * sizeof(size_t);
#undef TEST_UTIL_QUERY_EINVAL
/* Examine output for valid call */
TEST_UTIL_VALID("query");
assert_zu_le(NFREE_READ(out), NREGS_READ(out),
"Extent free count exceeded region count");
assert_zu_le(NREGS_READ(out), SIZE_READ(out),
"Extent region count exceeded size");
assert_zu_ne(NREGS_READ(out), 0,
"Extent region count must be positive");
assert_zu_ne(SIZE_READ(out), 0, "Extent size must be positive");
if (config_stats) {
assert_zu_le(BIN_NFREE_READ(out), BIN_NREGS_READ(out),
"Bin free count exceeded region count");
assert_zu_ne(BIN_NREGS_READ(out), 0,
"Bin region count must be positive");
assert_zu_le(NFREE_READ(out), BIN_NFREE_READ(out),
"Extent free count exceeded bin free count");
assert_zu_le(NREGS_READ(out), BIN_NREGS_READ(out),
"Extent region count exceeded bin region count");
assert_zu_eq(BIN_NREGS_READ(out) % NREGS_READ(out), 0,
"Bin region count isn't a multiple of extent region count");
assert_zu_le(NREGS_READ(out) - NFREE_READ(out),
BIN_NREGS_READ(out) - BIN_NFREE_READ(out),
"Extent utilized count exceeded bin utilized count");
} else {
assert_zu_eq(BIN_NFREE_READ(out), 0,
"Bin free count should be zero when stats are disabled");
assert_zu_eq(BIN_NREGS_READ(out), 0,
"Bin region count should be zero when stats are disabled");
}
assert_ptr_not_null(SLABCUR_READ(out), "Current slab is null");
assert_true(NFREE_READ(out) == 0 || SLABCUR_READ(out) <= p,
"Allocation should follow first fit principle");
#undef BIN_NREGS_READ
#undef BIN_NFREE_READ
#undef SIZE_READ
#undef NREGS_READ
#undef NFREE_READ
#undef COUNTS
#undef SLABCUR_READ
free(out_ref);
free(out);
free(p);
}
TEST_END
TEST_BEGIN(test_utilization_batch_query) {
void *p = mallocx(1, 0);
void *q = mallocx(1, 0);
void *in[] = {p, q};
size_t in_sz = sizeof(const void *) * 2;
size_t out[] = {-1, -1, -1, -1, -1, -1};
size_t out_sz = sizeof(size_t) * 6;
size_t out_ref[] = {-1, -1, -1, -1, -1, -1};
size_t out_sz_ref = out_sz;
assert_ptr_not_null(p, "test pointer allocation failed");
assert_ptr_not_null(q, "test pointer allocation failed");
/* Test invalid argument(s) errors */
#define TEST_UTIL_BATCH_EINVAL(a, b, c, d, why_inval) \
TEST_UTIL_EINVAL("batch_query", a, b, c, d, why_inval)
TEST_UTIL_BATCH_EINVAL(NULL, &out_sz, in, in_sz, "old is NULL");
TEST_UTIL_BATCH_EINVAL(out, NULL, in, in_sz, "oldlenp is NULL");
TEST_UTIL_BATCH_EINVAL(out, &out_sz, NULL, in_sz, "newp is NULL");
TEST_UTIL_BATCH_EINVAL(out, &out_sz, in, 0, "newlen is zero");
in_sz -= 1;
TEST_UTIL_BATCH_EINVAL(out, &out_sz, in, in_sz,
"newlen is not an exact multiple");
in_sz += 1;
out_sz_ref = out_sz -= 2 * sizeof(size_t);
TEST_UTIL_BATCH_EINVAL(out, &out_sz, in, in_sz,
"*oldlenp is not an exact multiple");
out_sz_ref = out_sz += 2 * sizeof(size_t);
in_sz -= sizeof(const void *);
TEST_UTIL_BATCH_EINVAL(out, &out_sz, in, in_sz,
"*oldlenp and newlen do not match");
in_sz += sizeof(const void *);
#undef TEST_UTIL_BATCH_EINVAL
/* Examine output for valid calls */
#define TEST_UTIL_BATCH_VALID TEST_UTIL_VALID("batch_query")
#define TEST_EQUAL_REF(i, message) \
assert_d_eq(memcmp(out + (i) * 3, out_ref + (i) * 3, 3), 0, message)
#define NFREE_READ(out, i) out[(i) * 3]
#define NREGS_READ(out, i) out[(i) * 3 + 1]
#define SIZE_READ(out, i) out[(i) * 3 + 2]
out_sz_ref = out_sz /= 2;
in_sz /= 2;
TEST_UTIL_BATCH_VALID;
assert_zu_le(NFREE_READ(out, 0), NREGS_READ(out, 0),
"Extent free count exceeded region count");
assert_zu_le(NREGS_READ(out, 0), SIZE_READ(out, 0),
"Extent region count exceeded size");
assert_zu_ne(NREGS_READ(out, 0), 0,
"Extent region count must be positive");
assert_zu_ne(SIZE_READ(out, 0), 0, "Extent size must be positive");
TEST_EQUAL_REF(1, "Should not overwrite content beyond what's needed");
in_sz *= 2;
out_sz_ref = out_sz *= 2;
memcpy(out_ref, out, 3 * sizeof(size_t));
TEST_UTIL_BATCH_VALID;
TEST_EQUAL_REF(0, "Statistics should be stable across calls");
assert_zu_le(NFREE_READ(out, 1), NREGS_READ(out, 1),
"Extent free count exceeded region count");
assert_zu_eq(NREGS_READ(out, 0), NREGS_READ(out, 1),
"Extent region count should be same for same region size");
assert_zu_eq(SIZE_READ(out, 0), SIZE_READ(out, 1),
"Extent size should be same for same region size");
#undef SIZE_READ
#undef NREGS_READ
#undef NFREE_READ
#undef TEST_EQUAL_REF
#undef TEST_UTIL_BATCH_VALID
free(q);
free(p);
}
TEST_END
#undef TEST_UTIL_VALID
#undef TEST_UTIL_EINVAL
int
main(void) {
return test(
@ -883,5 +1075,7 @@ main(void) {
test_arenas_lookup,
test_stats_arenas,
test_hooks,
test_hooks_exhaustion);
test_hooks_exhaustion,
test_utilization_query,
test_utilization_batch_query);
}