src/collectors/slabinfo.plugin/slabinfo.c
// SPDX-License-Identifier: GPL-3.0-or-later
#include "daemon/common.h"
#include "libnetdata/required_dummies.h"
#define PLUGIN_SLABINFO_NAME "slabinfo.plugin"
#define PLUGIN_SLABINFO_PROCFILE "/proc/slabinfo"
#define CHART_TYPE "mem"
#define CHART_FAMILY "slab"
#define CHART_PRIO 3000
// #define slabdebug(...) if (debug) { fprintf(stderr, __VA_ARGS__); }
#define slabdebug(args...) do { \
if (debug) { \
fprintf(stderr, "slabinfo.plugin DEBUG (%04d@%-10.10s:%-15.15s)::", __LINE__, __FILE__, __FUNCTION__); \
fprintf(stderr, ##args); \
fprintf(stderr, "\n"); \
} \
} while(0)
int running = 1;
int debug = 0;
size_t lines_discovered = 0;
int redraw_chart = 0;
// ----------------------------------------------------------------------------
// Slabinfo format :
// format 2.1 Was provided by 57ed3eda977a215f054102b460ab0eb5d8d112e6 (2.6.24-rc6) as:
// seq_puts(m, "# name <active_objs> <num_objs> <objsize> <objperslab> <pagesperslab>");
// seq_puts(m, " : tunables <limit> <batchcount> <sharedfactor>");
// seq_puts(m, " : slabdata <active_slabs> <num_slabs> <sharedavail>");
//
// With max values:
// seq_printf(m, "%-17s %6lu %6lu %6u %4u %4d",
// cache_name(s), sinfo.active_objs, sinfo.num_objs, s->size, sinfo.objects_per_slab, (1 << sinfo.cache_order));
// seq_printf(m, " : tunables %4u %4u %4u",
// sinfo.limit, sinfo.batchcount, sinfo.shared);
// seq_printf(m, " : slabdata %6lu %6lu %6lu",
// sinfo.active_slabs, sinfo.num_slabs, sinfo.shared_avail);
//
// If CONFIG_DEBUG_SLAB is set, it will also add columns from slabinfo_show_stats (for SLAB only):
// seq_printf(m, " : globalstat %7lu %6lu %5lu %4lu %4lu %4lu %4lu %4lu %4lu",
// allocs, high, grown, reaped, errors, max_freeable, node_allocs, node_frees, overflows);
// seq_printf(m, " : cpustat %6lu %6lu %6lu %6lu",
// allochit, allocmiss, freehit, freemiss);
//
// Implementation choices:
// - Iterates through a linked list of kmem_cache.
// - Name is a char* from struct kmem_cache (mm/slab.h).
// - max name size found is 24:
// grep -roP 'kmem_cache_create\(".+"'| awk '{split($0,a,"\""); print a[2],length(a[2]); }' | sort -k2 -n
// - Using uint64 everywhere, as types fits and allows to use standard helpers
struct slabinfo {
// procfile fields
const char *name;
uint64_t active_objs;
uint64_t num_objs;
uint64_t obj_size;
uint64_t obj_per_slab;
uint64_t pages_per_slab;
uint64_t tune_limit;
uint64_t tune_batchcnt;
uint64_t tune_shared_factor;
uint64_t data_active_slabs;
uint64_t data_num_slabs;
uint64_t data_shared_avail;
// Calculated fields
uint64_t mem_usage;
uint64_t mem_waste;
uint8_t obj_filling;
uint32_t hash;
struct slabinfo *next;
} *slabinfo_root = NULL, *slabinfo_next = NULL, *slabinfo_last_used = NULL;
// The code is very inspired from "proc_net_dev.c" and "perf_plugin.c"
// Get the existing object, or create a new one
static struct slabinfo *get_slabstruct(const char *name) {
struct slabinfo *s;
slabdebug("--> Requested slabstruct %s", name);
uint32_t hash = simple_hash(name);
// Search it, from the next to the end
for (s = slabinfo_next; s; s = s->next) {
if ((hash = s->hash) && !strcmp(name, s->name)) {
slabdebug("<-- Found existing slabstruct after %s", slabinfo_last_used->name);
// Prepare the next run
slabinfo_next = s->next;
slabinfo_last_used = s;
return s;
}
}
// Search it from the beginning to the last position we used
for (s = slabinfo_root; s != slabinfo_last_used; s = s->next) {
if (hash == s->hash && !strcmp(name, s->name)) {
slabdebug("<-- Found existing slabstruct after root %s", slabinfo_root->name);
slabinfo_next = s->next;
slabinfo_last_used = s;
return s;
}
}
// Create a new one
s = callocz(1, sizeof(struct slabinfo));
s->name = strdupz(name);
s->hash = hash;
// Add it to the current position
if (slabinfo_root) {
slabdebug("<-- Creating new slabstruct after %s", slabinfo_last_used->name);
s->next = slabinfo_last_used->next;
slabinfo_last_used->next = s;
slabinfo_last_used = s;
}
else {
slabdebug("<-- Creating new slabstruct as root");
slabinfo_root = slabinfo_last_used = s;
}
return s;
}
// Read a full pass of slabinfo to update the structs
struct slabinfo *read_file_slabinfo() {
slabdebug("-> Reading procfile %s", PLUGIN_SLABINFO_PROCFILE);
static procfile *ff = NULL;
static long slab_pagesize = 0;
if (unlikely(!slab_pagesize)) {
slab_pagesize = sysconf(_SC_PAGESIZE);
slabdebug(" Discovered pagesize: %ld", slab_pagesize);
}
if(unlikely(!ff)) {
ff = procfile_reopen(ff, PLUGIN_SLABINFO_PROCFILE, " ,:" , PROCFILE_FLAG_DEFAULT);
if(unlikely(!ff)) {
collector_error("<- Cannot open file '%s", PLUGIN_SLABINFO_PROCFILE);
exit(1);
}
}
ff = procfile_readall(ff);
if(unlikely(!ff)) {
collector_error("<- Cannot read file '%s'", PLUGIN_SLABINFO_PROCFILE);
exit(0);
}
// Iterate on all lines to populate / update the slabinfo struct
size_t lines = procfile_lines(ff), l;
if (unlikely(lines != lines_discovered)) {
lines_discovered = lines;
redraw_chart = 1;
}
slabdebug(" Read %lu lines from procfile", (unsigned long)lines);
for(l = 2; l < lines; l++) {
if (unlikely(procfile_linewords(ff, l) < 14)) {
slabdebug(" Line %zu has only %zu words, skipping", l, procfile_linewords(ff,l));
continue;
}
char *name = procfile_lineword(ff, l, 0);
struct slabinfo *s = get_slabstruct(name);
s->active_objs = str2uint64_t(procfile_lineword(ff, l, 1), NULL);
s->num_objs = str2uint64_t(procfile_lineword(ff, l, 2), NULL);
s->obj_size = str2uint64_t(procfile_lineword(ff, l, 3), NULL);
s->obj_per_slab = str2uint64_t(procfile_lineword(ff, l, 4), NULL);
s->pages_per_slab = str2uint64_t(procfile_lineword(ff, l, 5), NULL);
s->tune_limit = str2uint64_t(procfile_lineword(ff, l, 7), NULL);
s->tune_batchcnt = str2uint64_t(procfile_lineword(ff, l, 8), NULL);
s->tune_shared_factor = str2uint64_t(procfile_lineword(ff, l, 9), NULL);
s->data_active_slabs = str2uint64_t(procfile_lineword(ff, l, 11), NULL);
s->data_num_slabs = str2uint64_t(procfile_lineword(ff, l, 12), NULL);
s->data_shared_avail = str2uint64_t(procfile_lineword(ff, l, 13), NULL);
uint32_t memperslab = s->pages_per_slab * slab_pagesize;
// Internal fragmentation: loss per slab, due to objects not being a multiple of pagesize
//uint32_t lossperslab = memperslab - s->obj_per_slab * s->obj_size;
// Total usage = slabs * pages per slab * page size
s->mem_usage = (uint64_t)(s->data_num_slabs * memperslab);
// Wasted memory (filling): slabs allocated but not filled: sum total slab - sum total objects
s->mem_waste = s->mem_usage - (uint64_t)(s->active_objs * s->obj_size);
//if (s->data_num_slabs > 1)
// s->mem_waste += s->data_num_slabs * lossperslab;
// Slab filling efficiency
if (s->num_objs > 0)
s->obj_filling = 100 * s->active_objs / s->num_objs;
else
s->obj_filling = 0;
slabdebug(" Updated slab %s: %"PRIu64" %"PRIu64" %"PRIu64" %"PRIu64" %"PRIu64" / %"PRIu64" %"PRIu64" %"PRIu64" / %"PRIu64" %"PRIu64" %"PRIu64" / %"PRIu64" %"PRIu64" %hhu",
name, s->active_objs, s->num_objs, s->obj_size, s->obj_per_slab, s->pages_per_slab,
s->tune_limit, s->tune_batchcnt, s->tune_shared_factor,
s->data_active_slabs, s->data_num_slabs, s->data_shared_avail,
s->mem_usage, s->mem_waste, s->obj_filling);
}
return slabinfo_root;
}
unsigned int do_slab_stats(int update_every) {
static unsigned int loops = 0;
struct slabinfo *sactive = NULL, *s = NULL;
// Main processing loop
while (running) {
sactive = read_file_slabinfo();
// Init Charts
if (unlikely(redraw_chart)) {
redraw_chart = 0;
// Memory Usage
printf("CHART %s.%s '' 'Memory Usage' 'B' '%s' '' line %d %d %s\n"
, CHART_TYPE
, "slabmemory"
, CHART_FAMILY
, CHART_PRIO
, update_every
, PLUGIN_SLABINFO_NAME
);
for (s = sactive; s; s = s->next) {
printf("DIMENSION %s '' absolute 1 1\n", s->name);
}
// Slab active usage (filling)
printf("CHART %s.%s '' 'Object Filling' '%%' '%s' '' line %d %d %s\n"
, CHART_TYPE
, "slabfilling"
, CHART_FAMILY
, CHART_PRIO + 1
, update_every
, PLUGIN_SLABINFO_NAME
);
for (s = sactive; s; s = s->next) {
printf("DIMENSION %s '' absolute 1 1\n", s->name);
}
// Memory waste
printf("CHART %s.%s '' 'Memory waste' 'B' '%s' '' line %d %d %s\n"
, CHART_TYPE
, "slabwaste"
, CHART_FAMILY
, CHART_PRIO + 2
, update_every
, PLUGIN_SLABINFO_NAME
);
for (s = sactive; s; s = s->next) {
printf("DIMENSION %s '' absolute 1 1\n", s->name);
}
}
//
// Memory usage
//
printf("BEGIN %s.%s\n"
, CHART_TYPE
, "slabmemory"
);
for (s = sactive; s; s = s->next) {
printf("SET %s = %"PRIu64"\n"
, s->name
, s->mem_usage
);
}
printf("END\n");
//
// Slab active usage
//
printf("BEGIN %s.%s\n"
, CHART_TYPE
, "slabfilling"
);
for (s = sactive; s; s = s->next) {
printf("SET %s = %u\n"
, s->name
, s->obj_filling
);
}
printf("END\n");
//
// Memory waste
//
printf("BEGIN %s.%s\n"
, CHART_TYPE
, "slabwaste"
);
for (s = sactive; s; s = s->next) {
printf("SET %s = %"PRIu64"\n"
, s->name
, s->mem_waste
);
}
printf("END\n");
loops++;
sleep(update_every);
}
return loops;
}
// ----------------------------------------------------------------------------
// main
void usage(void) {
fprintf(stderr, "%s\n", program_name);
exit(1);
}
int main(int argc, char **argv) {
clocks_init();
nd_log_initialize_for_external_plugins("slabinfo.plugin");
program_name = argv[0];
program_version = "0.1";
int update_every = 1, i, n, freq = 0;
for (i = 1; i < argc; i++) {
// Frequency parsing
if(isdigit(*argv[i]) && !freq) {
n = (int) str2l(argv[i]);
if (n > 0) {
if (n >= UPDATE_EVERY_MAX) {
collector_error("Invalid interval value: %s", argv[i]);
exit(1);
}
freq = n;
}
}
else if (strcmp("debug", argv[i]) == 0) {
debug = 1;
continue;
}
else {
fprintf(stderr,
"netdata slabinfo.plugin %s\n"
"This program is a data collector plugin for netdata.\n"
"\n"
"Available command line options:\n"
"\n"
" COLLECTION_FREQUENCY data collection frequency in seconds\n"
" minimum: %d\n"
"\n"
" debug enable verbose output\n"
" default: disabled\n"
"\n",
program_version,
update_every
);
exit(1);
}
}
if(freq >= update_every)
update_every = freq;
else if(freq)
collector_error("update frequency %d seconds is too small for slabinfo. Using %d.", freq, update_every);
// Call the main function. Time drift to be added
do_slab_stats(update_every);
return 0;
}