diff options
Diffstat (limited to 'collectors/ebpf.plugin/ebpf_mdflush.c')
| -rw-r--r-- | collectors/ebpf.plugin/ebpf_mdflush.c | 312 |
1 files changed, 312 insertions, 0 deletions
diff --git a/collectors/ebpf.plugin/ebpf_mdflush.c b/collectors/ebpf.plugin/ebpf_mdflush.c new file mode 100644 index 000000000..e2420ec8e --- /dev/null +++ b/collectors/ebpf.plugin/ebpf_mdflush.c @@ -0,0 +1,312 @@ +// 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; +} |