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Re-compute active_defrag_running after adjusting defrag configurations (#13020) 

Currently, once active defrag starts, we can not adjust
active_defrag_running
downwards. This is because active_defrag_running will be dynamically
compute
based on the fragmentation, we think we should not lower the effort when
the
fragmentation drops.

However, we need to note that active_defrag_running will also be
dynamically
computed based on configurations. In this case, we are not respecting
cycle-min
or cycle-max. Some people may realize halfway through that defrag
consumes a
lot and want to adjust it.

Previously we could only turn off activedefrag and then turn it on again
to
adjust active_defrag_running downwards. So in this PR, when a active
defrag
configuration change is made, we will re-compute it.

These configuration items are:
- active-defrag-cycle-min
- active-defrag-cycle-max
- active-defrag-threshold-upper
This commit is contained in:
Binbin 2024-02-06 19:39:07 +08:00 committed by GitHub
parent 87eaf119cd
commit 13bd3643c2
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GPG Key ID: B5690EEEBB952194
5 changed files with 41 additions and 8 deletions
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12
src/config.c
View File

@ -2478,6 +2478,12 @@ static int updatePort(const char **err) {
return 1;
}
static int updateDefragConfiguration(const char **err) {
UNUSED(err);
server.active_defrag_configuration_changed = 1;
return 1;
}
static int updateJemallocBgThread(const char **err) {
UNUSED(err);
set_jemalloc_bg_thread(server.jemalloc_bg_thread);
@ -3164,10 +3170,10 @@ standardConfig static_configs[] = {
createIntConfig("list-max-listpack-size", "list-max-ziplist-size", MODIFIABLE_CONFIG, INT_MIN, INT_MAX, server.list_max_listpack_size, -2, INTEGER_CONFIG, NULL, NULL),
createIntConfig("tcp-keepalive", NULL, MODIFIABLE_CONFIG, 0, INT_MAX, server.tcpkeepalive, 300, INTEGER_CONFIG, NULL, NULL),
createIntConfig("cluster-migration-barrier", NULL, MODIFIABLE_CONFIG, 0, INT_MAX, server.cluster_migration_barrier, 1, INTEGER_CONFIG, NULL, NULL),
createIntConfig("active-defrag-cycle-min", NULL, MODIFIABLE_CONFIG, 1, 99, server.active_defrag_cycle_min, 1, INTEGER_CONFIG, NULL, NULL), /* Default: 1% CPU min (at lower threshold) */
createIntConfig("active-defrag-cycle-max", NULL, MODIFIABLE_CONFIG, 1, 99, server.active_defrag_cycle_max, 25, INTEGER_CONFIG, NULL, NULL), /* Default: 25% CPU max (at upper threshold) */
createIntConfig("active-defrag-cycle-min", NULL, MODIFIABLE_CONFIG, 1, 99, server.active_defrag_cycle_min, 1, INTEGER_CONFIG, NULL, updateDefragConfiguration), /* Default: 1% CPU min (at lower threshold) */
createIntConfig("active-defrag-cycle-max", NULL, MODIFIABLE_CONFIG, 1, 99, server.active_defrag_cycle_max, 25, INTEGER_CONFIG, NULL, updateDefragConfiguration), /* Default: 25% CPU max (at upper threshold) */
createIntConfig("active-defrag-threshold-lower", NULL, MODIFIABLE_CONFIG, 0, 1000, server.active_defrag_threshold_lower, 10, INTEGER_CONFIG, NULL, NULL), /* Default: don't defrag when fragmentation is below 10% */
createIntConfig("active-defrag-threshold-upper", NULL, MODIFIABLE_CONFIG, 0, 1000, server.active_defrag_threshold_upper, 100, INTEGER_CONFIG, NULL, NULL), /* Default: maximum defrag force at 100% fragmentation */
createIntConfig("active-defrag-threshold-upper", NULL, MODIFIABLE_CONFIG, 0, 1000, server.active_defrag_threshold_upper, 100, INTEGER_CONFIG, NULL, updateDefragConfiguration), /* Default: maximum defrag force at 100% fragmentation */
createIntConfig("lfu-log-factor", NULL, MODIFIABLE_CONFIG, 0, INT_MAX, server.lfu_log_factor, 10, INTEGER_CONFIG, NULL, NULL),
createIntConfig("lfu-decay-time", NULL, MODIFIABLE_CONFIG, 0, INT_MAX, server.lfu_decay_time, 1, INTEGER_CONFIG, NULL, NULL),
createIntConfig("replica-priority", "slave-priority", MODIFIABLE_CONFIG, 0, INT_MAX, server.slave_priority, 100, INTEGER_CONFIG, NULL, NULL),

23
src/defrag.c
View File

@ -898,7 +898,8 @@ void computeDefragCycles(void) {
return;
}
/* Calculate the adaptive aggressiveness of the defrag */
/* Calculate the adaptive aggressiveness of the defrag based on the current
* fragmentation and configurations. */
int cpu_pct = INTERPOLATE(frag_pct,
server.active_defrag_threshold_lower,
server.active_defrag_threshold_upper,
@ -907,10 +908,15 @@ void computeDefragCycles(void) {
cpu_pct = LIMIT(cpu_pct,
server.active_defrag_cycle_min,
server.active_defrag_cycle_max);
/* We allow increasing the aggressiveness during a scan, but don't
* reduce it. */
if (cpu_pct > server.active_defrag_running) {
/* Normally we allow increasing the aggressiveness during a scan, but don't
* reduce it, since we should not lower the aggressiveness when fragmentation
* drops. But when a configuration is made, we should reconsider it. */
if (cpu_pct > server.active_defrag_running ||
server.active_defrag_configuration_changed)
{
server.active_defrag_running = cpu_pct;
server.active_defrag_configuration_changed = 0;
serverLog(LL_VERBOSE,
"Starting active defrag, frag=%.0f%%, frag_bytes=%zu, cpu=%d%%",
frag_pct, frag_bytes, cpu_pct);
@ -940,6 +946,7 @@ void activeDefragCycle(void) {
if (server.active_defrag_running) {
/* if active defrag was disabled mid-run, start from fresh next time. */
server.active_defrag_running = 0;
server.active_defrag_configuration_changed = 0;
if (db)
listEmpty(db->defrag_later);
defrag_later_current_key = NULL;
@ -963,6 +970,14 @@ void activeDefragCycle(void) {
run_with_period(1000) {
computeDefragCycles();
}
/* Normally it is checked once a second, but when there is a configuration
* change, we want to check it as soon as possible. */
if (server.active_defrag_configuration_changed) {
computeDefragCycles();
server.active_defrag_configuration_changed = 0;
}
if (!server.active_defrag_running)
return;

3
src/server.c
View File

@ -1556,7 +1556,7 @@ void whileBlockedCron(void) {
* make sure it was done. */
serverAssert(server.blocked_last_cron);
/* In case we where called too soon, leave right away. This way one time
/* In case we were called too soon, leave right away. This way one time
* jobs after the loop below don't need an if. and we don't bother to start
* latency monitor if this function is called too often. */
if (server.blocked_last_cron >= server.mstime)
@ -2066,6 +2066,7 @@ void initServerConfig(void) {
server.aof_last_incr_size = 0;
server.aof_last_incr_fsync_offset = 0;
server.active_defrag_running = 0;
server.active_defrag_configuration_changed = 0;
server.notify_keyspace_events = 0;
server.blocked_clients = 0;
memset(server.blocked_clients_by_type,0,

2
src/server.h
View File

@ -1737,6 +1737,8 @@ struct redisServer {
int sanitize_dump_payload; /* Enables deep sanitization for ziplist and listpack in RDB and RESTORE. */
int skip_checksum_validation; /* Disable checksum validation for RDB and RESTORE payload. */
int jemalloc_bg_thread; /* Enable jemalloc background thread */
int active_defrag_configuration_changed; /* defrag configuration has been changed and need to reconsider
* active_defrag_running in computeDefragCycles. */
size_t active_defrag_ignore_bytes; /* minimum amount of fragmentation waste to start active defrag */
int active_defrag_threshold_lower; /* minimum percentage of fragmentation to start active defrag */
int active_defrag_threshold_upper; /* maximum percentage of fragmentation at which we use maximum effort */

9
tests/unit/memefficiency.tcl
View File

@ -80,6 +80,15 @@ run_solo {defrag} {
fail "defrag not started."
}
# This test usually runs for a while, during this interval, we test the range.
assert_range [s active_defrag_running] 65 75
r config set active-defrag-cycle-min 1
r config set active-defrag-cycle-max 1
after 120 ;# serverCron only updates the info once in 100ms
assert_range [s active_defrag_running] 1 1
r config set active-defrag-cycle-min 65
r config set active-defrag-cycle-max 75
# Wait for the active defrag to stop working.
wait_for_condition 2000 100 {
[s active_defrag_running] eq 0