1 files changed, 273 insertions, 0 deletions
diff --git a/collectors/ebpf.plugin/ebpf_softirq.c b/collectors/ebpf.plugin/ebpf_softirq.c
new file mode 100644
index 000000000..119c1222a
--- /dev/null
+++ b/collectors/ebpf.plugin/ebpf_softirq.c
@@ -0,0 +1,273 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#include "ebpf.h"
+#include "ebpf_softirq.h"
+
+struct config softirq_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 SOFTIRQ_MAP_LATENCY 0
+static ebpf_local_maps_t softirq_maps[] = {
+    {
+        .name = "tbl_softirq",
+        .internal_input = NETDATA_SOFTIRQ_MAX_IRQS,
+        .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
+    }
+};
+
+#define SOFTIRQ_TP_CLASS_IRQ "irq"
+static ebpf_tracepoint_t softirq_tracepoints[] = {
+    {.enabled = false, .class = SOFTIRQ_TP_CLASS_IRQ, .event = "softirq_entry"},
+    {.enabled = false, .class = SOFTIRQ_TP_CLASS_IRQ, .event = "softirq_exit"},
+    /* end */
+    {.enabled = false, .class = NULL, .event = NULL}
+};
+
+// these must be in the order defined by the kernel:
+// https://elixir.bootlin.com/linux/v5.12.19/source/include/trace/events/irq.h#L13
+static softirq_val_t softirq_vals[] = {
+    {.name = "HI", .latency = 0},
+    {.name = "TIMER", .latency = 0},
+    {.name = "NET_TX", .latency = 0},
+    {.name = "NET_RX", .latency = 0},
+    {.name = "BLOCK", .latency = 0},
+    {.name = "IRQ_POLL", .latency = 0},
+    {.name = "TASKLET", .latency = 0},
+    {.name = "SCHED", .latency = 0},
+    {.name = "HRTIMER", .latency = 0},
+    {.name = "RCU", .latency = 0},
+};
+
+// tmp store for soft IRQ values we get from a per-CPU eBPF map.
+static softirq_ebpf_val_t *softirq_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 softirq_threads = {"SOFTIRQ KERNEL",
+                                                    NULL, NULL, 1, NULL,
+                                                    NULL, NULL };
+
+/**
+ * Clean up the main thread.
+ *
+ * @param ptr thread data.
+ */
+static void softirq_cleanup(void *ptr)
+{
+    for (int i = 0; softirq_tracepoints[i].class != NULL; i++) {
+        ebpf_disable_tracepoint(&softirq_tracepoints[i]);
+    }
+
+    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(softirq_ebpf_vals);
+    freez(softirq_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);
+    }
+}
+
+/*****************************************************************
+ *  MAIN LOOP
+ *****************************************************************/
+
+static void softirq_read_latency_map()
+{
+    int fd = softirq_maps[SOFTIRQ_MAP_LATENCY].map_fd;
+    int i;
+    for (i = 0; i < NETDATA_SOFTIRQ_MAX_IRQS; i++) {
+        int test = bpf_map_lookup_elem(fd, &i, softirq_ebpf_vals);
+        if (unlikely(test < 0)) {
+            continue;
+        }
+
+        uint64_t total_latency = 0;
+        int cpu_i;
+        int end = ebpf_nprocs;
+        for (cpu_i = 0; cpu_i < end; cpu_i++) {
+            total_latency += softirq_ebpf_vals[cpu_i].latency/1000;
+        }
+
+        softirq_vals[i].latency = total_latency;
+    }
+}
+
+/**
+ * Read eBPF maps for soft IRQ.
+ */
+static void *softirq_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_SOFTIRQ_SLEEP_MS * em->update_every;
+    while (!close_ebpf_plugin) {
+        usec_t dt = heartbeat_next(&hb, step);
+        UNUSED(dt);
+
+        softirq_read_latency_map();
+    }
+
+    read_thread_closed = 1;
+    return NULL;
+}
+
+static void softirq_create_charts(int update_every)
+{
+    ebpf_create_chart(
+        NETDATA_EBPF_SYSTEM_GROUP,
+        "softirq_latency",
+        "Software IRQ latency",
+        EBPF_COMMON_DIMENSION_MILLISECONDS,
+        "softirqs",
+        NULL,
+        NETDATA_EBPF_CHART_TYPE_STACKED,
+        NETDATA_CHART_PRIO_SYSTEM_SOFTIRQS+1,
+        NULL, NULL, 0, update_every,
+        NETDATA_EBPF_MODULE_NAME_SOFTIRQ
+    );
+
+    fflush(stdout);
+}
+
+static void softirq_create_dims()
+{
+    uint32_t i;
+    for (i = 0; i < NETDATA_SOFTIRQ_MAX_IRQS; i++) {
+        ebpf_write_global_dimension(
+            softirq_vals[i].name, softirq_vals[i].name,
+            ebpf_algorithms[NETDATA_EBPF_INCREMENTAL_IDX]
+        );
+    }
+}
+
+static inline void softirq_write_dims()
+{
+    uint32_t i;
+    for (i = 0; i < NETDATA_SOFTIRQ_MAX_IRQS; i++) {
+        write_chart_dimension(softirq_vals[i].name, softirq_vals[i].latency);
+    }
+}
+
+/**
+* Main loop for this collector.
+*/
+static void softirq_collector(ebpf_module_t *em)
+{
+    softirq_ebpf_vals = callocz(ebpf_nprocs, sizeof(softirq_ebpf_val_t));
+
+    // create reader thread.
+    softirq_threads.thread = mallocz(sizeof(netdata_thread_t));
+    softirq_threads.start_routine = softirq_reader;
+    netdata_thread_create(
+        softirq_threads.thread,
+        softirq_threads.name,
+        NETDATA_THREAD_OPTION_JOINABLE,
+        softirq_reader,
+        em
+    );
+
+    // create chart and static dims.
+    pthread_mutex_lock(&lock);
+    softirq_create_charts(em->update_every);
+    softirq_create_dims();
+    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 IRQs.
+            write_begin_chart(NETDATA_EBPF_SYSTEM_GROUP, "softirq_latency");
+            softirq_write_dims();
+            write_end_chart();
+
+            pthread_mutex_unlock(&lock);
+        }
+        pthread_mutex_unlock(&collect_data_mutex);
+    }
+}
+
+/*****************************************************************
+ *  EBPF SOFTIRQ THREAD
+ *****************************************************************/
+
+/**
+ * Soft IRQ latency thread.
+ *
+ * @param ptr a `ebpf_module_t *`.
+ * @return always NULL.
+ */
+void *ebpf_softirq_thread(void *ptr)
+{
+    netdata_thread_cleanup_push(softirq_cleanup, ptr);
+
+    ebpf_module_t *em = (ebpf_module_t *)ptr;
+    em->maps = softirq_maps;
+
+    if (!em->enabled) {
+        goto endsoftirq;
+    }
+
+    if (ebpf_enable_tracepoints(softirq_tracepoints) == 0) {
+        em->enabled = CONFIG_BOOLEAN_NO;
+        goto endsoftirq;
+    }
+
+    probe_links = ebpf_load_program(ebpf_plugin_dir, em, kernel_string, &objects);
+    if (!probe_links) {
+        goto endsoftirq;
+    }
+
+    softirq_collector(em);
+
+endsoftirq:
+    netdata_thread_cleanup_pop(1);
+
+    return NULL;
+}