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RSS aware maxmemory: algorith #1 implemented.

This commit is contained in:
antirez 2014-11-17 15:10:03 +01:00
parent 5f185413df
commit 01671edcca
3 changed files with 68 additions and 15 deletions
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6
src/config.c
View File

@ -226,8 +226,7 @@ void loadServerConfigFromString(char *config) {
}
} else if (!strcasecmp(argv[0],"maxmemory") && argc == 2) {
server.maxmemory = memtoll(argv[1],NULL);
server.maxmemory_adjusted = server.maxmemory;
server.maxmemory_enforced = server.maxmemory;
server.maxmemory_enforced = (double) server.maxmemory / server.maxmemory_frag_guess;
} else if (!strcasecmp(argv[0],"rss-aware-maxmemory") && argc==2) {
if ((server.rss_aware_maxmemory = yesnotoi(argv[1])) == -1) {
err = "argument must be 'yes' or 'no'"; goto loaderr;
@ -637,8 +636,7 @@ void configSetCommand(redisClient *c) {
if (getLongLongFromObject(o,&ll) == REDIS_ERR ||
ll < 0) goto badfmt;
server.maxmemory = ll;
server.maxmemory_adjusted = ll;
server.maxmemory_enforced = ll;
server.maxmemory_enforced = (double) server.maxmemory / server.maxmemory_frag_guess;
if (server.maxmemory) {
if (server.maxmemory < zmalloc_used_memory()) {
redisLog(REDIS_WARNING,"WARNING: the new maxmemory value set via CONFIG SET is smaller than the current memory usage. This will result in keys eviction and/or inability to accept new write commands depending on the maxmemory-policy.");

68
src/redis.c
View File

@ -1433,8 +1433,8 @@ void initServerConfig(void) {
server.maxclients = REDIS_MAX_CLIENTS;
server.bpop_blocked_clients = 0;
server.maxmemory = REDIS_DEFAULT_MAXMEMORY;
server.maxmemory_enforced = REDIS_DEFAULT_MAXMEMORY;
server.maxmemory_adjusted = REDIS_DEFAULT_MAXMEMORY;
server.maxmemory_frag_guess = REDIS_DEFAULT_MAXMEMORY_FRAG_GUESS;
server.maxmemory_enforced = (double) REDIS_DEFAULT_MAXMEMORY / server.maxmemory_frag_guess;
server.maxmemory_policy = REDIS_DEFAULT_MAXMEMORY_POLICY;
server.maxmemory_samples = REDIS_DEFAULT_MAXMEMORY_SAMPLES;
server.rss_aware_maxmemory = REDIS_DEFAULT_RSS_AWARE_MAXMEMORY;
@ -3157,7 +3157,7 @@ void evictionPoolPopulate(dict *sampledict, dict *keydict, struct evictionPoolEn
}
int freeMemoryIfNeeded(void) {
size_t mem_used, mem_tofree, mem_freed;
size_t mem_used, mem_tofree, mem_freed, mem_target = server.maxmemory;
int slaves = listLength(server.slaves);
mstime_t latency;
@ -3183,14 +3183,72 @@ int freeMemoryIfNeeded(void) {
mem_used -= aofRewriteBufferSize();
}
/* If we use RSS aware maxmemory, update the target memory using
* the current fragmentation figure. */
#ifdef HAVE_RSS_REPORTING
if (server.rss_aware_maxmemory &&
server.maxmemory_policy != REDIS_MAXMEMORY_NO_EVICTION)
{
static unsigned long iterations = 0;
static unsigned long sampling_stage = 1;
static float last_observed_frag = 0;
/* For some time, we analyze what happens during memory pressure, when
* objects are evicted and reallocated. */
if (mem_used > server.maxmemory_enforced) {
unsigned long sample_cycles = 1000000;
/* Every sample_cycle cycles we sample the fragmentation, and
* compare it with the previos one. If it is no longer raising,
* we take it as a guess of the fragmentation with this workload. */
if (sampling_stage && iterations < sample_cycles) {
iterations++;
if (iterations == sample_cycles) {
float current_frag = zmalloc_get_fragmentation_ratio(server.resident_set_size);
if (last_observed_frag == 0) {
/* First sample we get. */
last_observed_frag = current_frag;
} else {
if (current_frag <= last_observed_frag) {
size_t enforced_new;
sampling_stage = 0;
server.maxmemory_frag_guess = current_frag;
/* Update the global fragmentation guess and use
* it (also used it for successive
* "CONFIG SET maxmemory" commands). */
if (server.maxmemory_frag_guess < 1)
server.maxmemory_frag_guess = 1;
else if (server.maxmemory_frag_guess > 2)
server.maxmemory_frag_guess = 2;
/* Only set the new limit if it is higher than our
* initial guess, otherwise it is futile: RSS will
* not go backward anyway. */
enforced_new = (double) server.maxmemory /
server.maxmemory_frag_guess;
if (enforced_new > server.maxmemory_enforced)
server.maxmemory_enforced = enforced_new;
redisLog(REDIS_NOTICE,"RSS aware maxmemory, fragmentation looks stable at: %f", server.maxmemory_frag_guess);
}
last_observed_frag = current_frag;
}
iterations = 0;
}
}
}
mem_target = server.maxmemory_enforced;
}
#endif
/* Check if we are over the memory limit. */
if (mem_used <= server.maxmemory) return REDIS_OK;
if (mem_used <= mem_target) return REDIS_OK;
if (server.maxmemory_policy == REDIS_MAXMEMORY_NO_EVICTION)
return REDIS_ERR; /* We need to free memory, but policy forbids. */
/* Compute how much memory we need to free. */
mem_tofree = mem_used - server.maxmemory;
mem_tofree = mem_used - mem_target;
mem_freed = 0;
latencyStartMonitor(latency);
while (mem_freed < mem_tofree) {

9
src/redis.h
View File

@ -121,6 +121,7 @@ typedef long long mstime_t; /* millisecond time type. */
#define REDIS_DEFAULT_REPL_DISABLE_TCP_NODELAY 0
#define REDIS_DEFAULT_MAXMEMORY 0
#define REDIS_DEFAULT_MAXMEMORY_SAMPLES 5
#define REDIS_DEFAULT_MAXMEMORY_FRAG_GUESS 1.4
#define REDIS_DEFAULT_RSS_AWARE_MAXMEMORY 0
#define REDIS_DEFAULT_AOF_FILENAME "appendonly.aof"
#define REDIS_DEFAULT_AOF_NO_FSYNC_ON_REWRITE 0
@ -840,14 +841,10 @@ struct redisServer {
unsigned long long maxmemory; /* Max number of memory bytes to use */
int maxmemory_policy; /* Policy for key eviction */
int maxmemory_samples; /* Pricision of random sampling */
/* RSS aware maxmemory additional state:
* the adjusted maxmemory is adjusted for fragmentation, however we
* enforce maxmemory_enforced instead, which follows the adjusted value
* in small steps at eviction cycle to avoid too fast changes in the
* enforced maxmemory value. */
/* RSS aware maxmemory additional state. */
int rss_aware_maxmemory; /* Non zero if enabled. */
unsigned long long maxmemory_adjusted; /* Maxmemory adjusted for frag. */
unsigned long long maxmemory_enforced; /* Currently enforced maxmemory. */
float maxmemory_frag_guess; /* Guessed fragmentation. */
/* Blocked clients */
unsigned int bpop_blocked_clients; /* Number of clients blocked by lists */
list *unblocked_clients; /* list of clients to unblock before next loop */