Viewing file:  ebpf_mdflush.c (8.1 KB) -rw-r--r--
Select action/file-type:
 (+) |  (+) |  (+) | Code (+) | Session (+) |  (+) | SDB (+) |  (+) |  (+) |  (+) |  (+) |  (+) |
// SPDX-License-Identifier: GPL-3.0-or-later
#include "ebpf.h"
#include "ebpf_mdflush.h"
struct config mdflush_config = { .first_section = NULL,
.last_section = NULL,
.mutex = NETDATA_MUTEX_INITIALIZER,
.index = { .avl_tree = { .root = NULL, .compar = appconfig_section_compare },
.rwlock = AVL_LOCK_INITIALIZER } };
#define MDFLUSH_MAP_COUNT 0
static ebpf_local_maps_t mdflush_maps[] = {
{
.name = "tbl_mdflush",
.internal_input = 1024,
.user_input = 0,
.type = NETDATA_EBPF_MAP_STATIC,
.map_fd = ND_EBPF_MAP_FD_NOT_INITIALIZED
},
/* end */
{
.name = NULL,
.internal_input = 0,
.user_input = 0,
.type = NETDATA_EBPF_MAP_CONTROLLER,
.map_fd = ND_EBPF_MAP_FD_NOT_INITIALIZED
}
};
// store for "published" data from the reader thread, which the collector
// thread will write to netdata agent.
static avl_tree_lock mdflush_pub;
// tmp store for mdflush values we get from a per-CPU eBPF map.
static mdflush_ebpf_val_t *mdflush_ebpf_vals = NULL;
static struct bpf_link **probe_links = NULL;
static struct bpf_object *objects = NULL;
static int read_thread_closed = 1;
static struct netdata_static_thread mdflush_threads = {"MDFLUSH KERNEL",
NULL, NULL, 1, NULL,
NULL, NULL };
/**
* Clean up the main thread.
*
* @param ptr thread data.
*/
static void mdflush_cleanup(void *ptr)
{
ebpf_module_t *em = (ebpf_module_t *)ptr;
if (!em->enabled) {
return;
}
heartbeat_t hb;
heartbeat_init(&hb);
uint32_t tick = 1 * USEC_PER_MS;
while (!read_thread_closed) {
usec_t dt = heartbeat_next(&hb, tick);
UNUSED(dt);
}
freez(mdflush_ebpf_vals);
freez(mdflush_threads.thread);
if (probe_links) {
struct bpf_program *prog;
size_t i = 0 ;
bpf_object__for_each_program(prog, objects) {
bpf_link__destroy(probe_links[i]);
i++;
}
bpf_object__close(objects);
}
}
/**
* Compare mdflush values.
*
* @param a `netdata_mdflush_t *`.
* @param b `netdata_mdflush_t *`.
*
* @return 0 if a==b, 1 if a>b, -1 if a<b.
*/
static int mdflush_val_cmp(void *a, void *b)
{
netdata_mdflush_t *ptr1 = a;
netdata_mdflush_t *ptr2 = b;
if (ptr1->unit > ptr2->unit) {
return 1;
}
else if (ptr1->unit < ptr2->unit) {
return -1;
}
else {
return 0;
}
}
static void mdflush_read_count_map()
{
int mapfd = mdflush_maps[MDFLUSH_MAP_COUNT].map_fd;
mdflush_ebpf_key_t curr_key = (uint32_t)-1;
mdflush_ebpf_key_t key = (uint32_t)-1;
netdata_mdflush_t search_v;
netdata_mdflush_t *v = NULL;
while (bpf_map_get_next_key(mapfd, &curr_key, &key) == 0) {
curr_key = key;
// get val for this key.
int test = bpf_map_lookup_elem(mapfd, &key, mdflush_ebpf_vals);
if (unlikely(test < 0)) {
continue;
}
// is this record saved yet?
//
// if not, make a new one, mark it as unsaved for now, and continue; we
// will insert it at the end after all of its values are correctly set,
// so that we can safely publish it to the collector within a single,
// short locked operation.
//
// otherwise simply continue; we will only update the flush count,
// which can be republished safely without a lock.
//
// NOTE: lock isn't strictly necessary for this initial search, as only
// this thread does writing, but the AVL is using a read-write lock so
// there is no congestion.
bool v_is_new = false;
search_v.unit = key;
v = (netdata_mdflush_t *)avl_search_lock(
&mdflush_pub,
(avl_t *)&search_v
);
if (unlikely(v == NULL)) {
// flush count can only be added reliably at a later time.
// when they're added, only then will we AVL insert.
v = callocz(1, sizeof(netdata_mdflush_t));
v->unit = key;
sprintf(v->disk_name, "md%u", key);
v->dim_exists = false;
v_is_new = true;
}
// we must add up count value for this record across all CPUs.
uint64_t total_cnt = 0;
int i;
int end = (running_on_kernel < NETDATA_KERNEL_V4_15) ? 1 : ebpf_nprocs;
for (i = 0; i < end; i++) {
total_cnt += mdflush_ebpf_vals[i];
}
// can now safely publish count for existing records.
v->cnt = total_cnt;
// can now safely publish new record.
if (v_is_new) {
avl_t *check = avl_insert_lock(&mdflush_pub, (avl_t *)v);
if (check != (avl_t *)v) {
error("Internal error, cannot insert the AVL tree.");
}
}
}
}
/**
* Read eBPF maps for mdflush.
*/
static void *mdflush_reader(void *ptr)
{
read_thread_closed = 0;
heartbeat_t hb;
heartbeat_init(&hb);
ebpf_module_t *em = (ebpf_module_t *)ptr;
usec_t step = NETDATA_MDFLUSH_SLEEP_MS * em->update_every;
while (!close_ebpf_plugin) {
usec_t dt = heartbeat_next(&hb, step);
UNUSED(dt);
mdflush_read_count_map();
}
read_thread_closed = 1;
return NULL;
}
static void mdflush_create_charts(int update_every)
{
ebpf_create_chart(
"mdstat",
"mdstat_flush",
"MD flushes",
"flushes",
"flush (eBPF)",
"md.flush",
NETDATA_EBPF_CHART_TYPE_STACKED,
NETDATA_CHART_PRIO_MDSTAT_FLUSH,
NULL, NULL, 0, update_every,
NETDATA_EBPF_MODULE_NAME_MDFLUSH
);
fflush(stdout);
}
// callback for avl tree traversal on `mdflush_pub`.
static int mdflush_write_dims(void *entry, void *data)
{
UNUSED(data);
netdata_mdflush_t *v = entry;
// records get dynamically added in, so add the dim if we haven't yet.
if (!v->dim_exists) {
ebpf_write_global_dimension(
v->disk_name, v->disk_name,
ebpf_algorithms[NETDATA_EBPF_INCREMENTAL_IDX]
);
v->dim_exists = true;
}
write_chart_dimension(v->disk_name, v->cnt);
return 1;
}
/**
* Main loop for this collector.
*/
static void mdflush_collector(ebpf_module_t *em)
{
mdflush_ebpf_vals = callocz(ebpf_nprocs, sizeof(mdflush_ebpf_val_t));
avl_init_lock(&mdflush_pub, mdflush_val_cmp);
// create reader thread.
mdflush_threads.thread = mallocz(sizeof(netdata_thread_t));
mdflush_threads.start_routine = mdflush_reader;
netdata_thread_create(
mdflush_threads.thread,
mdflush_threads.name,
NETDATA_THREAD_OPTION_JOINABLE,
mdflush_reader,
em
);
// create chart and static dims.
pthread_mutex_lock(&lock);
mdflush_create_charts(em->update_every);
pthread_mutex_unlock(&lock);
// loop and read from published data until ebpf plugin is closed.
int update_every = em->update_every;
int counter = update_every - 1;
while (!close_ebpf_plugin) {
pthread_mutex_lock(&collect_data_mutex);
pthread_cond_wait(&collect_data_cond_var, &collect_data_mutex);
if (++counter == update_every) {
counter = 0;
pthread_mutex_lock(&lock);
// write dims now for all hitherto discovered devices.
write_begin_chart("mdstat", "mdstat_flush");
avl_traverse_lock(&mdflush_pub, mdflush_write_dims, NULL);
write_end_chart();
pthread_mutex_unlock(&lock);
}
pthread_mutex_unlock(&collect_data_mutex);
}
}
/**
* mdflush thread.
*
* @param ptr a `ebpf_module_t *`.
* @return always NULL.
*/
void *ebpf_mdflush_thread(void *ptr)
{
netdata_thread_cleanup_push(mdflush_cleanup, ptr);
ebpf_module_t *em = (ebpf_module_t *)ptr;
em->maps = mdflush_maps;
if (!em->enabled) {
goto endmdflush;
}
probe_links = ebpf_load_program(ebpf_plugin_dir, em, kernel_string, &objects);
if (!probe_links) {
goto endmdflush;
}
mdflush_collector(em);
endmdflush:
netdata_thread_cleanup_pop(1);
return NULL;
}
|