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Ehooks: Add head tracking.

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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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60
src/ehooks.c
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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