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Adding real allocator fragmentation to INFO and MEMORY command + active defrag test

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other fixes / improvements:
- LUA script memory isn't taken from zmalloc (taken from libc malloc)
  so it can cause high fragmentation ratio to be displayed (which is false)
- there was a problem with "fragmentation" info being calculated from
  RSS and used_memory sampled at different times (now sampling them together)

other details:
- adding a few more allocator info fields to INFO and MEMORY commands
- improve defrag test to measure defrag latency of big keys
- increasing the accuracy of the defrag test (by looking at real grag info)
  this way we can use an even lower threshold and still avoid false positives
- keep the old (total) "fragmentation" field unchanged, but add new ones for spcific things
- add these the MEMORY DOCTOR command
- deduct LUA memory from the rss in case of non jemalloc allocator (one for which we don't "allocator active/used")
- reduce sampling rate of the rss and allocator info
This commit is contained in:
Oran Agra
2018-02-18 17:36:21 +02:00
parent be1b4aa9aa
commit 806736cdf9
8 changed files with 337 additions and 76 deletions
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61
src/server.c
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@ -1007,8 +1007,33 @@ int serverCron(struct aeEventLoop *eventLoop, long long id, void *clientData) {
if (zmalloc_used_memory() > server.stat_peak_memory)
server.stat_peak_memory = zmalloc_used_memory();
/* Sample the RSS here since this is a relatively slow call. */
server.resident_set_size = zmalloc_get_rss();
run_with_period(10) {
/* Sample the RSS and other metrics here since this is a relatively slow call.
* We must sample the zmalloc_used at the same time we take the rss, otherwise
* the frag ratio calculate may be off (ratio of two samples at different times) */
server.cron_malloc_stats.process_rss = zmalloc_get_rss();
server.cron_malloc_stats.zmalloc_used = zmalloc_used_memory();
/* Sampling the allcator info can be slow too.
* The fragmentation ratio it'll show is potentically more accurate
* it excludes other RSS pages such as: shared libraries, LUA and other non-zmalloc
* allocations, and allocator reserved pages that can be pursed (all not actual frag) */
zmalloc_get_allocator_info(&server.cron_malloc_stats.allocator_allocated,
&server.cron_malloc_stats.allocator_active,
&server.cron_malloc_stats.allocator_resident);
/* in case the allocator isn't providing these stats, fake them so that
* fragmention info still shows some (inaccurate metrics) */
if (!server.cron_malloc_stats.allocator_resident) {
/* LUA memory isn't part of zmalloc_used, but it is part of the process RSS,
* so we must desuct it in order to be able to calculate correct
* "allocator fragmentation" ratio */
size_t lua_memory = lua_gc(server.lua,LUA_GCCOUNT,0)*1024LL;
server.cron_malloc_stats.allocator_resident = server.cron_malloc_stats.process_rss - lua_memory;
}
if (!server.cron_malloc_stats.allocator_active)
server.cron_malloc_stats.allocator_active = server.cron_malloc_stats.allocator_resident;
if (!server.cron_malloc_stats.allocator_allocated)
server.cron_malloc_stats.allocator_allocated = server.cron_malloc_stats.zmalloc_used;
}
/* We received a SIGTERM, shutting down here in a safe way, as it is
* not ok doing so inside the signal handler. */
@ -1924,7 +1949,11 @@ void initServer(void) {
server.stat_peak_memory = 0;
server.stat_rdb_cow_bytes = 0;
server.stat_aof_cow_bytes = 0;
server.resident_set_size = 0;
server.cron_malloc_stats.zmalloc_used = 0;
server.cron_malloc_stats.process_rss = 0;
server.cron_malloc_stats.allocator_allocated = 0;
server.cron_malloc_stats.allocator_active = 0;
server.cron_malloc_stats.allocator_resident = 0;
server.lastbgsave_status = C_OK;
server.aof_last_write_status = C_OK;
server.aof_last_write_errno = 0;
@ -2974,7 +3003,7 @@ sds genRedisInfoString(char *section) {
bytesToHuman(peak_hmem,server.stat_peak_memory);
bytesToHuman(total_system_hmem,total_system_mem);
bytesToHuman(used_memory_lua_hmem,memory_lua);
bytesToHuman(used_memory_rss_hmem,server.resident_set_size);
bytesToHuman(used_memory_rss_hmem,server.cron_malloc_stats.process_rss);
bytesToHuman(maxmemory_hmem,server.maxmemory);
if (sections++) info = sdscat(info,"\r\n");
@ -2991,6 +3020,9 @@ sds genRedisInfoString(char *section) {
"used_memory_startup:%zu\r\n"
"used_memory_dataset:%zu\r\n"
"used_memory_dataset_perc:%.2f%%\r\n"
"allocator_allocated:%zu\r\n"
"allocator_active:%zu\r\n"
"allocator_resident:%zu\r\n"
"total_system_memory:%lu\r\n"
"total_system_memory_human:%s\r\n"
"used_memory_lua:%lld\r\n"
@ -2998,13 +3030,20 @@ sds genRedisInfoString(char *section) {
"maxmemory:%lld\r\n"
"maxmemory_human:%s\r\n"
"maxmemory_policy:%s\r\n"
"allocator_frag_ratio:%.2f\r\n"
"allocator_frag_bytes:%zu\r\n"
"allocator_rss_ratio:%.2f\r\n"
"allocator_rss_bytes:%zu\r\n"
"rss_overhead_ratio:%.2f\r\n"
"rss_overhead_bytes:%zu\r\n"
"mem_fragmentation_ratio:%.2f\r\n"
"mem_fragmentation_bytes:%zu\r\n"
"mem_allocator:%s\r\n"
"active_defrag_running:%d\r\n"
"lazyfree_pending_objects:%zu\r\n",
zmalloc_used,
hmem,
server.resident_set_size,
server.cron_malloc_stats.process_rss,
used_memory_rss_hmem,
server.stat_peak_memory,
peak_hmem,
@ -3013,6 +3052,9 @@ sds genRedisInfoString(char *section) {
mh->startup_allocated,
mh->dataset,
mh->dataset_perc,
server.cron_malloc_stats.allocator_allocated,
server.cron_malloc_stats.allocator_active,
server.cron_malloc_stats.allocator_resident,
(unsigned long)total_system_mem,
total_system_hmem,
memory_lua,
@ -3020,7 +3062,14 @@ sds genRedisInfoString(char *section) {
server.maxmemory,
maxmemory_hmem,
evict_policy,
mh->fragmentation,
mh->allocator_frag,
mh->allocator_frag_bytes,
mh->allocator_rss,
mh->allocator_rss_bytes,
mh->rss_extra,
mh->rss_extra_bytes,
mh->total_frag, /* this is the total RSS overhead, including fragmentation, */
mh->total_frag_bytes, /* named so for backwards compatibility */
ZMALLOC_LIB,
server.active_defrag_running,
lazyfreeGetPendingObjectsCount()