cregit-Linux how code gets into the kernel

Release 4.7 samples/bpf/lathist_user.c

Directory: samples/bpf
/* 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 "libbpf.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'; }

Contributors

PersonTokensPropCommitsCommitProp
daniel wagnerdaniel wagner78100.00%1100.00%
Total78100.00%1100.00%


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); } } }

Contributors

PersonTokensPropCommitsCommitProp
daniel wagnerdaniel wagner144100.00%1100.00%
Total144100.00%1100.00%


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_lookup_elem(fd, &key, &value); cpu_hist[c].data[i] = value; if (value > cpu_hist[c].max) cpu_hist[c].max = value; } } }

Contributors

PersonTokensPropCommitsCommitProp
daniel wagnerdaniel wagner122100.00%1100.00%
Total122100.00%1100.00%


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; }

Contributors

PersonTokensPropCommitsCommitProp
daniel wagnerdaniel wagner80100.00%1100.00%
Total80100.00%1100.00%


Overall Contributors

PersonTokensPropCommitsCommitProp
daniel wagnerdaniel wagner480100.00%1100.00%
Total480100.00%1100.00%
Directory: samples/bpf
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