Ehooks: Add head tracking.

This commit is contained in:
David Goldblatt 2019-12-11 17:23:24 -08:00 committed by David Goldblatt
parent 09475bf8ac
commit 0704516245
5 changed files with 68 additions and 66 deletions

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@ -467,20 +467,12 @@ edata_prof_alloc_time_set(edata_t *edata, nstime_t *t) {
static inline bool
edata_is_head_get(edata_t *edata) {
if (maps_coalesce) {
not_reached();
}
return (bool)((edata->e_bits & EDATA_BITS_IS_HEAD_MASK) >>
EDATA_BITS_IS_HEAD_SHIFT);
}
static inline void
edata_is_head_set(edata_t *edata, bool is_head) {
if (maps_coalesce) {
not_reached();
}
edata->e_bits = (edata->e_bits & ~EDATA_BITS_IS_HEAD_MASK) |
((uint64_t)is_head << EDATA_BITS_IS_HEAD_SHIFT);
}
@ -502,9 +494,7 @@ edata_init(edata_t *edata, unsigned arena_ind, void *addr, size_t size,
edata_committed_set(edata, committed);
edata_dumpable_set(edata, dumpable);
ql_elm_new(edata, ql_link);
if (!maps_coalesce) {
edata_is_head_set(edata, is_head == EXTENT_IS_HEAD);
}
edata_is_head_set(edata, is_head == EXTENT_IS_HEAD);
if (config_prof) {
edata_prof_tctx_set(edata, NULL);
}

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@ -1,16 +1,21 @@
#ifndef JEMALLOC_INTERNAL_EHOOKS_H
#define JEMALLOC_INTERNAL_EHOOKS_H
#include "jemalloc/internal/atomic.h"
#include "jemalloc/internal/extent_mmap.h"
/*
* This module is the internal interface to the extent hooks (both
* user-specified and external). Eventually, this will give us the flexibility
* to use multiple different versions of user-visible extent-hook APIs under a
* single user interface.
*
* Current API expansions (not available to anyone but the default hooks yet):
* - Head state tracking. Hooks can decide whether or not to merge two
* extents based on whether or not one of them is the head (i.e. was
* allocated on its own). The later extent loses its "head" status.
*/
#include "jemalloc/internal/atomic.h"
#include "jemalloc/internal/extent_mmap.h"
extern const extent_hooks_t ehooks_default_extent_hooks;
typedef struct ehooks_s ehooks_t;
@ -43,7 +48,8 @@ bool ehooks_default_purge_lazy_impl(void *addr, size_t offset, size_t length);
bool ehooks_default_purge_forced_impl(void *addr, size_t offset, size_t length);
#endif
bool ehooks_default_split_impl();
bool ehooks_default_merge_impl(void *addr_a, void *addr_b);
bool ehooks_default_merge_impl(tsdn_t *tsdn, void *addr_a, bool head_a,
void *addr_b, bool head_b);
void ehooks_default_zero_impl(void *addr, size_t size);
/*
@ -314,10 +320,12 @@ ehooks_split(tsdn_t *tsdn, ehooks_t *ehooks, void *addr, size_t size,
static inline bool
ehooks_merge(tsdn_t *tsdn, ehooks_t *ehooks, void *addr_a, size_t size_a,
void *addr_b, size_t size_b, bool committed, unsigned arena_ind) {
bool head_a, void *addr_b, size_t size_b, bool head_b, bool committed,
unsigned arena_ind) {
extent_hooks_t *extent_hooks = ehooks_get_extent_hooks_ptr(ehooks);
if (extent_hooks == &ehooks_default_extent_hooks) {
return ehooks_default_merge_impl(addr_a, addr_b);
return ehooks_default_merge_impl(tsdn, addr_a, head_a, addr_b,
head_b);
} else if (extent_hooks->merge == NULL) {
return true;
} else {

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@ -54,7 +54,6 @@ edata_t *extent_split_wrapper(tsdn_t *tsdn, arena_t *arena, ehooks_t *ehooks,
size_t size_b, szind_t szind_b, bool slab_b);
bool extent_merge_wrapper(tsdn_t *tsdn, arena_t *arena, ehooks_t *ehooks,
edata_t *a, edata_t *b);
bool extent_head_no_merge(edata_t *a, edata_t *b);
bool extent_boot(void);

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@ -183,8 +183,51 @@ ehooks_default_split(extent_hooks_t *extent_hooks, void *addr, size_t size,
return ehooks_default_split_impl();
}
static inline bool
ehooks_same_sn(tsdn_t *tsdn, void *addr_a, void *addr_b) {
edata_t *a = iealloc(tsdn, addr_a);
edata_t *b = iealloc(tsdn, addr_b);
return edata_sn_comp(a, b) == 0;
}
/*
* Returns true if the given extents can't be merged because of their head bit
* settings. Assumes the second extent has the higher address.
*/
static bool
ehooks_no_merge_heads(tsdn_t *tsdn, void *addr_a, bool head_a, void *addr_b,
bool head_b) {
/*
* When coalesce is not always allowed (Windows), only merge extents
* from the same VirtualAlloc region under opt.retain (in which case
* MEM_DECOMMIT is utilized for purging).
*/
if (maps_coalesce) {
return false;
}
if (!opt_retain) {
return true;
}
/* If b is a head extent, disallow the cross-region merge. */
if (head_b) {
/*
* Additionally, sn should not overflow with retain; sanity
* check that different regions have unique sn.
*/
assert(!ehooks_same_sn(tsdn, addr_a, addr_b));
return true;
}
assert(ehooks_same_sn(tsdn, addr_a, addr_b));
return false;
}
bool
ehooks_default_merge_impl(void *addr_a, void *addr_b) {
ehooks_default_merge_impl(tsdn_t *tsdn, void *addr_a, bool head_a, void *addr_b,
bool head_b) {
if (ehooks_no_merge_heads(tsdn, addr_a, head_a, addr_b, head_b)) {
return true;
}
if (!maps_coalesce && !opt_retain) {
return true;
}
@ -198,15 +241,12 @@ ehooks_default_merge_impl(void *addr_a, void *addr_b) {
static bool
ehooks_default_merge(extent_hooks_t *extent_hooks, void *addr_a, size_t size_a,
void *addr_b, size_t size_b, bool committed, unsigned arena_ind) {
if (!maps_coalesce) {
tsdn_t *tsdn = tsdn_fetch();
edata_t *a = iealloc(tsdn, addr_a);
edata_t *b = iealloc(tsdn, addr_b);
if (extent_head_no_merge(a, b)) {
return true;
}
}
return ehooks_default_merge_impl(addr_a, addr_b);
tsdn_t *tsdn = tsdn_fetch();
edata_t *a = iealloc(tsdn, addr_a);
bool head_a = edata_is_head_get(a);
edata_t *b = iealloc(tsdn, addr_b);
bool head_b = edata_is_head_get(b);
return ehooks_default_merge_impl(tsdn, addr_a, head_a, addr_b, head_b);
}
void

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@ -1493,38 +1493,6 @@ extent_split_wrapper(tsdn_t *tsdn, arena_t *arena, ehooks_t *ehooks,
slab_a, size_b, szind_b, slab_b, false);
}
/*
* Returns true if the given extents can't be merged because of their head bit
* settings. Assumes the second extent has the higher address.
*/
bool
extent_head_no_merge(edata_t *a, edata_t *b) {
assert(edata_base_get(a) < edata_base_get(b));
/*
* When coalesce is not always allowed (Windows), only merge extents
* from the same VirtualAlloc region under opt.retain (in which case
* MEM_DECOMMIT is utilized for purging).
*/
if (maps_coalesce) {
return false;
}
if (!opt_retain) {
return true;
}
/* If b is a head extent, disallow the cross-region merge. */
if (edata_is_head_get(b)) {
/*
* Additionally, sn should not overflow with retain; sanity
* check that different regions have unique sn.
*/
assert(edata_sn_comp(a, b) != 0);
return true;
}
assert(edata_sn_comp(a, b) == 0);
return false;
}
static bool
extent_merge_impl(tsdn_t *tsdn, arena_t *arena, ehooks_t *ehooks, edata_t *a,
edata_t *b, bool growing_retained) {
@ -1532,13 +1500,10 @@ extent_merge_impl(tsdn_t *tsdn, arena_t *arena, ehooks_t *ehooks, edata_t *a,
WITNESS_RANK_CORE, growing_retained ? 1 : 0);
assert(edata_base_get(a) < edata_base_get(b));
if (ehooks_merge_will_fail(ehooks) || extent_head_no_merge(a, b)) {
return true;
}
bool err = ehooks_merge(tsdn, ehooks, edata_base_get(a),
edata_size_get(a), edata_base_get(b), edata_size_get(b),
edata_committed_get(a), arena_ind_get(arena));
edata_size_get(a), edata_is_head_get(a), edata_base_get(b),
edata_size_get(b), edata_is_head_get(b), edata_committed_get(a),
arena_ind_get(arena));
if (err) {
return true;