v4.19.13 snapshot.
diff --git a/samples/bpf/lathist_user.c b/samples/bpf/lathist_user.c
new file mode 100644
index 0000000..c8e88cc
--- /dev/null
+++ b/samples/bpf/lathist_user.c
@@ -0,0 +1,103 @@
+/* Copyright (c) 2013-2015 PLUMgrid, http://plumgrid.com
+ * Copyright (c) 2015 BMW Car IT GmbH
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of version 2 of the GNU General Public
+ * License as published by the Free Software Foundation.
+ */
+#include <stdio.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <signal.h>
+#include <linux/bpf.h>
+#include <bpf/bpf.h>
+#include "bpf_load.h"
+
+#define MAX_ENTRIES 20
+#define MAX_CPU 4
+#define MAX_STARS 40
+
+struct cpu_hist {
+ long data[MAX_ENTRIES];
+ long max;
+};
+
+static struct cpu_hist cpu_hist[MAX_CPU];
+
+static void stars(char *str, long val, long max, int width)
+{
+ int i;
+
+ for (i = 0; i < (width * val / max) - 1 && i < width - 1; i++)
+ str[i] = '*';
+ if (val > max)
+ str[i - 1] = '+';
+ str[i] = '\0';
+}
+
+static void print_hist(void)
+{
+ char starstr[MAX_STARS];
+ struct cpu_hist *hist;
+ int i, j;
+
+ /* clear screen */
+ printf("\033[2J");
+
+ for (j = 0; j < MAX_CPU; j++) {
+ hist = &cpu_hist[j];
+
+ /* ignore CPUs without data (maybe offline?) */
+ if (hist->max == 0)
+ continue;
+
+ printf("CPU %d\n", j);
+ printf(" latency : count distribution\n");
+ for (i = 1; i <= MAX_ENTRIES; i++) {
+ stars(starstr, hist->data[i - 1], hist->max, MAX_STARS);
+ printf("%8ld -> %-8ld : %-8ld |%-*s|\n",
+ (1l << i) >> 1, (1l << i) - 1,
+ hist->data[i - 1], MAX_STARS, starstr);
+ }
+ }
+}
+
+static void get_data(int fd)
+{
+ long key, value;
+ int c, i;
+
+ for (i = 0; i < MAX_CPU; i++)
+ cpu_hist[i].max = 0;
+
+ for (c = 0; c < MAX_CPU; c++) {
+ for (i = 0; i < MAX_ENTRIES; i++) {
+ key = c * MAX_ENTRIES + i;
+ bpf_map_lookup_elem(fd, &key, &value);
+
+ cpu_hist[c].data[i] = value;
+ if (value > cpu_hist[c].max)
+ cpu_hist[c].max = value;
+ }
+ }
+}
+
+int main(int argc, char **argv)
+{
+ char filename[256];
+
+ snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
+
+ if (load_bpf_file(filename)) {
+ printf("%s", bpf_log_buf);
+ return 1;
+ }
+
+ while (1) {
+ get_data(map_fd[1]);
+ print_hist();
+ sleep(5);
+ }
+
+ return 0;
+}