tools: Add guest trace agent as a user tool
This patch adds a user tool, "trace agent" for sending trace data of a guest to a Host in low overhead. This agent has the following functions: - splice a page of ring-buffer to read_pipe without memory copying - splice the page from write_pipe to virtio-console without memory copying - write trace data to stdout by using -o option - controlled by start/stop orders from a Host Changes in v2: - Cleanup (change fprintf() to pr_err() and an include guard) Signed-off-by: Yoshihiro YUNOMAE <yoshihiro.yunomae.ez@hitachi.com> Acked-by: Amit Shah <amit.shah@redhat.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
Yoshihiro YUNOMAE
Rusty Russell
parent
8ca84a50e5
commit
108fc82596
6 changed files with 806 additions and 0 deletions
270
tools/virtio/virtio-trace/trace-agent.c
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270
tools/virtio/virtio-trace/trace-agent.c
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/*
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* Guest agent for virtio-trace
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*
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* Copyright (C) 2012 Hitachi, Ltd.
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* Created by Yoshihiro Yunomae <yoshihiro.yunomae.ez@hitachi.com>
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* Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
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*
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* Licensed under GPL version 2 only.
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*
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*/
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#define _GNU_SOURCE
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#include <limits.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include "trace-agent.h"
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#define PAGE_SIZE (sysconf(_SC_PAGE_SIZE))
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#define PIPE_DEF_BUFS 16
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#define PIPE_MIN_SIZE (PAGE_SIZE*PIPE_DEF_BUFS)
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#define PIPE_MAX_SIZE (1024*1024)
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#define READ_PATH_FMT \
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"/sys/kernel/debug/tracing/per_cpu/cpu%d/trace_pipe_raw"
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#define WRITE_PATH_FMT "/dev/virtio-ports/trace-path-cpu%d"
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#define CTL_PATH "/dev/virtio-ports/agent-ctl-path"
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pthread_mutex_t mutex_notify = PTHREAD_MUTEX_INITIALIZER;
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pthread_cond_t cond_wakeup = PTHREAD_COND_INITIALIZER;
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static int get_total_cpus(void)
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{
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int nr_cpus = (int)sysconf(_SC_NPROCESSORS_CONF);
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if (nr_cpus <= 0) {
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pr_err("Could not read cpus\n");
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goto error;
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} else if (nr_cpus > MAX_CPUS) {
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pr_err("Exceed max cpus(%d)\n", (int)MAX_CPUS);
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goto error;
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}
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return nr_cpus;
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error:
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exit(EXIT_FAILURE);
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}
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static void *agent_info_new(void)
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{
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struct agent_info *s;
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int i;
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s = zalloc(sizeof(struct agent_info));
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if (s == NULL) {
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pr_err("agent_info zalloc error\n");
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exit(EXIT_FAILURE);
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}
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s->pipe_size = PIPE_INIT;
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s->use_stdout = false;
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s->cpus = get_total_cpus();
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s->ctl_fd = -1;
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/* read/write threads init */
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for (i = 0; i < s->cpus; i++)
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s->rw_ti[i] = rw_thread_info_new();
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return s;
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}
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static unsigned long parse_size(const char *arg)
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{
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unsigned long value, round;
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char *ptr;
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value = strtoul(arg, &ptr, 10);
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switch (*ptr) {
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case 'K': case 'k':
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value <<= 10;
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break;
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case 'M': case 'm':
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value <<= 20;
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break;
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default:
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break;
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}
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if (value > PIPE_MAX_SIZE) {
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pr_err("Pipe size must be less than 1MB\n");
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goto error;
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} else if (value < PIPE_MIN_SIZE) {
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pr_err("Pipe size must be over 64KB\n");
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goto error;
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}
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/* Align buffer size with page unit */
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round = value & (PAGE_SIZE - 1);
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value = value - round;
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return value;
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error:
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return 0;
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}
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static void usage(char const *prg)
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{
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pr_err("usage: %s [-h] [-o] [-s <size of pipe>]\n", prg);
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}
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static const char *make_path(int cpu_num, bool this_is_write_path)
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{
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int ret;
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char *buf;
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buf = zalloc(PATH_MAX);
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if (buf == NULL) {
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pr_err("Could not allocate buffer\n");
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goto error;
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}
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if (this_is_write_path)
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/* write(output) path */
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ret = snprintf(buf, PATH_MAX, WRITE_PATH_FMT, cpu_num);
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else
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/* read(input) path */
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ret = snprintf(buf, PATH_MAX, READ_PATH_FMT, cpu_num);
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if (ret <= 0) {
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pr_err("Failed to generate %s path(CPU#%d):%d\n",
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this_is_write_path ? "read" : "write", cpu_num, ret);
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goto error;
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}
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return buf;
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error:
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free(buf);
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return NULL;
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}
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static const char *make_input_path(int cpu_num)
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{
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return make_path(cpu_num, false);
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}
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static const char *make_output_path(int cpu_num)
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{
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return make_path(cpu_num, true);
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}
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static void *agent_info_init(struct agent_info *s)
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{
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int cpu;
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const char *in_path = NULL;
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const char *out_path = NULL;
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/* init read/write threads */
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for (cpu = 0; cpu < s->cpus; cpu++) {
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/* set read(input) path per read/write thread */
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in_path = make_input_path(cpu);
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if (in_path == NULL)
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goto error;
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/* set write(output) path per read/write thread*/
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if (!s->use_stdout) {
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out_path = make_output_path(cpu);
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if (out_path == NULL)
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goto error;
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} else
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/* stdout mode */
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pr_debug("stdout mode\n");
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rw_thread_init(cpu, in_path, out_path, s->use_stdout,
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s->pipe_size, s->rw_ti[cpu]);
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}
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/* init controller of read/write threads */
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s->ctl_fd = rw_ctl_init((const char *)CTL_PATH);
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return NULL;
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error:
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exit(EXIT_FAILURE);
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}
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static void *parse_args(int argc, char *argv[], struct agent_info *s)
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{
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int cmd;
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unsigned long size;
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while ((cmd = getopt(argc, argv, "hos:")) != -1) {
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switch (cmd) {
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/* stdout mode */
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case 'o':
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s->use_stdout = true;
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break;
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/* size of pipe */
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case 's':
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size = parse_size(optarg);
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if (size == 0)
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goto error;
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s->pipe_size = size;
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break;
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case 'h':
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default:
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usage(argv[0]);
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goto error;
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}
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}
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agent_info_init(s);
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return NULL;
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error:
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exit(EXIT_FAILURE);
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}
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static void agent_main_loop(struct agent_info *s)
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{
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int cpu;
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pthread_t rw_thread_per_cpu[MAX_CPUS];
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/* Start all read/write threads */
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for (cpu = 0; cpu < s->cpus; cpu++)
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rw_thread_per_cpu[cpu] = rw_thread_run(s->rw_ti[cpu]);
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rw_ctl_loop(s->ctl_fd);
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/* Finish all read/write threads */
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for (cpu = 0; cpu < s->cpus; cpu++) {
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int ret;
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ret = pthread_join(rw_thread_per_cpu[cpu], NULL);
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if (ret != 0) {
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pr_err("pthread_join() error:%d (cpu %d)\n", ret, cpu);
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exit(EXIT_FAILURE);
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}
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}
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}
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static void agent_info_free(struct agent_info *s)
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{
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int i;
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close(s->ctl_fd);
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for (i = 0; i < s->cpus; i++) {
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close(s->rw_ti[i]->in_fd);
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close(s->rw_ti[i]->out_fd);
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close(s->rw_ti[i]->read_pipe);
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close(s->rw_ti[i]->write_pipe);
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free(s->rw_ti[i]);
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}
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free(s);
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}
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int main(int argc, char *argv[])
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{
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struct agent_info *s = NULL;
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s = agent_info_new();
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parse_args(argc, argv, s);
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agent_main_loop(s);
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agent_info_free(s);
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return 0;
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}
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