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HPA: Use dirtiest-first purging.

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This seems to be practically beneficial, despite some pathological corner cases.
This commit is contained in:
David Goldblatt
2021-02-08 14:11:37 -08:00
committed by David Goldblatt
parent 0f6c420f83
commit 73ca4b8ef8
6 changed files with 179 additions and 137 deletions
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76
include/jemalloc/internal/hpdata.h
View File

@@ -6,42 +6,6 @@
#include "jemalloc/internal/ql.h"
#include "jemalloc/internal/typed_list.h"
/*
* How badly we want to purge some region of memory. This is a temporary
* definition; it gets deleted in the next commit (where we adopt a more
* explicit dirtiest-first policy that only considers hugification status).
*/
enum hpdata_purge_level_e {
/*
* The level number is important -- we use it as indices into an array
* of size 2 (one for each purge level).
*/
/* "Regular" candidates for purging. */
hpdata_purge_level_default = 0,
/*
* Candidates for purging, but as a last resort. Practically,
* nonpreferred corresponds to hugified regions that are below the
* hugification threshold but have not yet reached the dehugification
* threshold, while strongly nonpreferred candidates are those which are
* above the hugification threshold.
*/
hpdata_purge_level_nonpreferred = 1,
hpdata_purge_level_strongly_nonpreferred = 2,
/* Don't purge, no matter what. */
hpdata_purge_level_never = 2,
/*
* How big an array has to be to accomodate all purge levels. This
* relies on the fact that we don't actually keep unpurgable hpdatas in
* a container.
*/
hpdata_purge_level_count = hpdata_purge_level_never
};
typedef enum hpdata_purge_level_e hpdata_purge_level_t;
/*
* The metadata representation we use for extents in hugepages. While the PAC
* uses the edata_t to represent both active and inactive extents, the HP only
@@ -87,9 +51,13 @@ struct hpdata_s {
bool h_alloc_allowed;
bool h_in_psset_alloc_container;
/* The same, but with purging. */
uint8_t h_purge_level;
uint8_t h_purge_container_level;
/*
* The same, but with purging. There's no corresponding
* h_in_psset_purge_container, because the psset (currently) always
* removes hpdatas from their containers during updates (to implement
* LRU for purging).
*/
bool h_purge_allowed;
/* And with hugifying. */
bool h_hugify_allowed;
@@ -200,26 +168,15 @@ hpdata_in_psset_alloc_container_set(hpdata_t *hpdata, bool in_container) {
hpdata->h_in_psset_alloc_container = in_container;
}
static inline hpdata_purge_level_t
hpdata_purge_level_get(const hpdata_t *hpdata) {
return (hpdata_purge_level_t)hpdata->h_purge_level;
static inline bool
hpdata_purge_allowed_get(const hpdata_t *hpdata) {
return hpdata->h_purge_allowed;
}
static inline void
hpdata_purge_level_set(hpdata_t *hpdata, hpdata_purge_level_t level) {
assert(level == hpdata_purge_level_never || !hpdata->h_mid_purge);
hpdata->h_purge_level = (uint8_t)level;
}
static inline hpdata_purge_level_t
hpdata_purge_container_level_get(const hpdata_t *hpdata) {
return (hpdata_purge_level_t)hpdata->h_purge_container_level;
}
static inline void
hpdata_purge_container_level_set(hpdata_t *hpdata, hpdata_purge_level_t level) {
assert(level != hpdata->h_purge_container_level);
hpdata->h_purge_container_level = level;
hpdata_purge_allowed_set(hpdata_t *hpdata, bool purge_allowed) {
assert(purge_allowed == false || !hpdata->h_mid_purge);
hpdata->h_purge_allowed = purge_allowed;
}
static inline bool
@@ -357,12 +314,7 @@ hpdata_consistent(hpdata_t *hpdata) {
return false;
}
if (hpdata_changing_state_get(hpdata)
&& ((hpdata->h_purge_level != hpdata_purge_level_never)
|| hpdata->h_hugify_allowed)) {
return false;
}
if (hpdata_purge_level_get(hpdata)
!= hpdata_purge_container_level_get(hpdata)) {
&& ((hpdata->h_purge_allowed) || hpdata->h_hugify_allowed)) {
return false;
}
if (hpdata_hugify_allowed_get(hpdata)

12
include/jemalloc/internal/psset.h
View File

@@ -20,6 +20,14 @@
*/
#define PSSET_NPSIZES 64
/*
* We keep two purge lists per page size class; one for hugified hpdatas (at
* index 2*pszind), and one for the non-hugified hpdatas (at index 2*pszind +
* 1). This lets us implement a preference for purging non-hugified hpdatas
* among similarly-dirty ones.
*/
#define PSSET_NPURGE_LISTS (2 * PSSET_NPSIZES)
typedef struct psset_bin_stats_s psset_bin_stats_t;
struct psset_bin_stats_s {
/* How many pageslabs are in this bin? */
@@ -71,7 +79,9 @@ struct psset_s {
*/
hpdata_empty_list_t empty;
/* Slabs which are available to be purged, ordered by purge level. */
hpdata_purge_list_t to_purge[hpdata_purge_level_count];
hpdata_purge_list_t to_purge[PSSET_NPURGE_LISTS];
/* Bitmap for which set bits correspond to non-empty purge lists. */
fb_group_t purge_bitmap[FB_NGROUPS(PSSET_NPURGE_LISTS)];
/* Slabs which are available to be hugified. */
hpdata_hugify_list_t to_hugify;
};