781e9545db
This patch adds a ftrace tracing backend which sends trace event to ftrace marker file. You can effectively compare qemu trace data and kernel(especially, kvm.ko when using KVM) trace data. The ftrace backend is restricted to Linux only. To try out the ftrace backend: $ ./configure --trace-backend=ftrace $ make if you use KVM, enable kvm events in ftrace: # sudo echo 1 > /sys/kernel/debug/tracing/events/kvm/enable After running qemu by root user, you can get the trace: # cat /sys/kernel/debug/tracing/trace Signed-off-by: Eiichi Tsukata <eiichi.tsukata.xh@hitachi.com> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
103 lines
2.5 KiB
C
103 lines
2.5 KiB
C
/*
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* Ftrace trace backend
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*
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* Copyright (C) 2013 Hitachi, Ltd.
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* Created by Eiichi Tsukata <eiichi.tsukata.xh@hitachi.com>
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*
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* This work is licensed under the terms of the GNU GPL, version 2. See
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* the COPYING file in the top-level directory.
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*
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*/
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#include <stdio.h>
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#include <string.h>
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#include <fcntl.h>
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#include <limits.h>
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#include "trace.h"
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#include "trace/control.h"
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int trace_marker_fd;
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static int find_debugfs(char *debugfs)
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{
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char type[100];
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FILE *fp;
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fp = fopen("/proc/mounts", "r");
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if (fp == NULL) {
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return 0;
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}
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while (fscanf(fp, "%*s %" STR(PATH_MAX) "s %99s %*s %*d %*d\n",
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debugfs, type) == 2) {
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if (strcmp(type, "debugfs") == 0) {
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break;
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}
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}
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fclose(fp);
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if (strcmp(type, "debugfs") != 0) {
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return 0;
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}
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return 1;
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}
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void trace_print_events(FILE *stream, fprintf_function stream_printf)
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{
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TraceEventID i;
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for (i = 0; i < trace_event_count(); i++) {
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TraceEvent *ev = trace_event_id(i);
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stream_printf(stream, "%s [Event ID %u] : state %u\n",
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trace_event_get_name(ev), i, trace_event_get_state_dynamic(ev));
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}
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}
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void trace_event_set_state_dynamic_backend(TraceEvent *ev, bool state)
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{
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ev->dstate = state;
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}
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bool trace_backend_init(const char *events, const char *file)
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{
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char debugfs[PATH_MAX];
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char path[PATH_MAX];
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int debugfs_found;
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int trace_fd = -1;
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if (file) {
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fprintf(stderr, "error: -trace file=...: "
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"option not supported by the selected tracing backend\n");
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return false;
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}
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debugfs_found = find_debugfs(debugfs);
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if (debugfs_found) {
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snprintf(path, PATH_MAX, "%s/tracing/tracing_on", debugfs);
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trace_fd = open(path, O_WRONLY);
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if (trace_fd < 0) {
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perror("Could not open ftrace 'tracing_on' file");
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return false;
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} else {
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if (write(trace_fd, "1", 1) < 0) {
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perror("Could not write to 'tracing_on' file");
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close(trace_fd);
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return false;
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}
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close(trace_fd);
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}
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snprintf(path, PATH_MAX, "%s/tracing/trace_marker", debugfs);
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trace_marker_fd = open(path, O_WRONLY);
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if (trace_marker_fd < 0) {
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perror("Could not open ftrace 'trace_marker' file");
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return false;
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}
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} else {
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fprintf(stderr, "debugfs is not mounted\n");
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return false;
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}
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trace_backend_init_events(events);
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return true;
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}
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