diff options
Diffstat (limited to 'tools/virtio/virtio-trace/trace-agent-rw.c')
| -rw-r--r-- | tools/virtio/virtio-trace/trace-agent-rw.c | 192 |
1 files changed, 192 insertions, 0 deletions
diff --git a/tools/virtio/virtio-trace/trace-agent-rw.c b/tools/virtio/virtio-trace/trace-agent-rw.c new file mode 100644 index 000000000000..3aace5ea4842 --- /dev/null +++ b/tools/virtio/virtio-trace/trace-agent-rw.c @@ -0,0 +1,192 @@ +/* + * Read/write thread of a guest agent for virtio-trace + * + * Copyright (C) 2012 Hitachi, Ltd. + * Created by Yoshihiro Yunomae <yoshihiro.yunomae.ez@hitachi.com> + * Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> + * + * Licensed under GPL version 2 only. + * + */ + +#define _GNU_SOURCE +#include <fcntl.h> +#include <stdio.h> +#include <stdlib.h> +#include <unistd.h> +#include <sys/syscall.h> +#include "trace-agent.h" + +#define READ_WAIT_USEC 100000 + +void *rw_thread_info_new(void) +{ + struct rw_thread_info *rw_ti; + + rw_ti = zalloc(sizeof(struct rw_thread_info)); + if (rw_ti == NULL) { + pr_err("rw_thread_info zalloc error\n"); + exit(EXIT_FAILURE); + } + + rw_ti->cpu_num = -1; + rw_ti->in_fd = -1; + rw_ti->out_fd = -1; + rw_ti->read_pipe = -1; + rw_ti->write_pipe = -1; + rw_ti->pipe_size = PIPE_INIT; + + return rw_ti; +} + +void *rw_thread_init(int cpu, const char *in_path, const char *out_path, + bool stdout_flag, unsigned long pipe_size, + struct rw_thread_info *rw_ti) +{ + int data_pipe[2]; + + rw_ti->cpu_num = cpu; + + /* set read(input) fd */ + rw_ti->in_fd = open(in_path, O_RDONLY); + if (rw_ti->in_fd == -1) { + pr_err("Could not open in_fd (CPU:%d)\n", cpu); + goto error; + } + + /* set write(output) fd */ + if (!stdout_flag) { + /* virtio-serial output mode */ + rw_ti->out_fd = open(out_path, O_WRONLY); + if (rw_ti->out_fd == -1) { + pr_err("Could not open out_fd (CPU:%d)\n", cpu); + goto error; + } + } else + /* stdout mode */ + rw_ti->out_fd = STDOUT_FILENO; + + if (pipe2(data_pipe, O_NONBLOCK) < 0) { + pr_err("Could not create pipe in rw-thread(%d)\n", cpu); + goto error; + } + + /* + * Size of pipe is 64kB in default based on fs/pipe.c. + * To read/write trace data speedy, pipe size is changed. + */ + if (fcntl(*data_pipe, F_SETPIPE_SZ, pipe_size) < 0) { + pr_err("Could not change pipe size in rw-thread(%d)\n", cpu); + goto error; + } + + rw_ti->read_pipe = data_pipe[1]; + rw_ti->write_pipe = data_pipe[0]; + rw_ti->pipe_size = pipe_size; + + return NULL; + +error: + exit(EXIT_FAILURE); +} + +/* Bind a thread to a cpu */ +static void bind_cpu(int cpu_num) +{ + cpu_set_t mask; + + CPU_ZERO(&mask); + CPU_SET(cpu_num, &mask); + + /* bind my thread to cpu_num by assigning zero to the first argument */ + if (sched_setaffinity(0, sizeof(mask), &mask) == -1) + pr_err("Could not set CPU#%d affinity\n", (int)cpu_num); +} + +static void *rw_thread_main(void *thread_info) +{ + ssize_t rlen, wlen; + ssize_t ret; + struct rw_thread_info *ts = (struct rw_thread_info *)thread_info; + + bind_cpu(ts->cpu_num); + + while (1) { + /* Wait for a read order of trace data by Host OS */ + if (!global_run_operation) { + pthread_mutex_lock(&mutex_notify); + pthread_cond_wait(&cond_wakeup, &mutex_notify); + pthread_mutex_unlock(&mutex_notify); + } + + if (global_sig_receive) + break; + + /* + * Each thread read trace_pipe_raw of each cpu bounding the + * thread, so contention of multi-threads does not occur. + */ + rlen = splice(ts->in_fd, NULL, ts->read_pipe, NULL, + ts->pipe_size, SPLICE_F_MOVE | SPLICE_F_MORE); + + if (rlen < 0) { + pr_err("Splice_read in rw-thread(%d)\n", ts->cpu_num); + goto error; + } else if (rlen == 0) { + /* + * If trace data do not exist or are unreadable not + * for exceeding the page size, splice_read returns + * NULL. Then, this waits for being filled the data in a + * ring-buffer. + */ + usleep(READ_WAIT_USEC); + pr_debug("Read retry(cpu:%d)\n", ts->cpu_num); + continue; + } + + wlen = 0; + + do { + ret = splice(ts->write_pipe, NULL, ts->out_fd, NULL, + rlen - wlen, + SPLICE_F_MOVE | SPLICE_F_MORE); + + if (ret < 0) { + pr_err("Splice_write in rw-thread(%d)\n", + ts->cpu_num); + goto error; + } else if (ret == 0) + /* + * When host reader is not in time for reading + * trace data, guest will be stopped. This is + * because char dev in QEMU is not supported + * non-blocking mode. Then, writer might be + * sleep in that case. + * This sleep will be removed by supporting + * non-blocking mode. + */ + sleep(1); + wlen += ret; + } while (wlen < rlen); + } + + return NULL; + +error: + exit(EXIT_FAILURE); +} + + +pthread_t rw_thread_run(struct rw_thread_info *rw_ti) +{ + int ret; + pthread_t rw_thread_per_cpu; + + ret = pthread_create(&rw_thread_per_cpu, NULL, rw_thread_main, rw_ti); + if (ret != 0) { + pr_err("Could not create a rw thread(%d)\n", rw_ti->cpu_num); + exit(EXIT_FAILURE); + } + + return rw_thread_per_cpu; +} |