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We can also do a direct splice from the transport FIFO to the output file descriptor instead of two through an additional pipe buffer. This patch implements specialized version for tracecmd_recorder data transfer for this case. Signed-off-by: Slavomir Kaslev --- include/trace-cmd/trace-cmd.h | 11 +++-- lib/trace-cmd/trace-recorder.c | 73 ++++++++++++++++++++++++---- tracecmd/include/trace-local.h | 4 +- tracecmd/trace-agent.c | 39 +++++++++++++-- tracecmd/trace-msg.c | 26 ++++++---- tracecmd/trace-record.c | 87 ++++++++++++++++++++++++++++++---- 6 files changed, 201 insertions(+), 39 deletions(-) diff --git a/include/trace-cmd/trace-cmd.h b/include/trace-cmd/trace-cmd.h index db5baa8..9a984c1 100644 --- a/include/trace-cmd/trace-cmd.h +++ b/include/trace-cmd/trace-cmd.h @@ -274,8 +274,9 @@ struct tracecmd_output *tracecmd_get_output_handle_fd(int fd); enum { TRACECMD_RECORD_NOSPLICE = (1 << 0), /* Use read instead of splice */ - TRACECMD_RECORD_SNAPSHOT = (1 << 1), /* extract from snapshot */ + TRACECMD_RECORD_SNAPSHOT = (1 << 1), /* Extract from snapshot */ TRACECMD_RECORD_BLOCK = (1 << 2), /* Block on splice write */ + TRACECMD_RECORD_NOBRASS = (1 << 3), /* Splice directly without a brass pipe */ }; void tracecmd_free_recorder(struct tracecmd_recorder *recorder); @@ -338,16 +339,16 @@ bool tracecmd_msg_done(struct tracecmd_msg_handle *msg_handle); void tracecmd_msg_set_done(struct tracecmd_msg_handle *msg_handle); int tracecmd_msg_send_trace_req(struct tracecmd_msg_handle *msg_handle, - int argc, char **argv); + int argc, char **argv, bool use_fifos); int tracecmd_msg_recv_trace_req(struct tracecmd_msg_handle *msg_handle, - int *argc, char ***argv); + int *argc, char ***argv, bool *use_fifos); int tracecmd_msg_send_trace_resp(struct tracecmd_msg_handle *msg_handle, int nr_cpus, int page_size, - unsigned int *ports); + unsigned int *ports, bool use_fifos); int tracecmd_msg_recv_trace_resp(struct tracecmd_msg_handle *msg_handle, int *nr_cpus, int *page_size, - unsigned int **ports); + unsigned int **ports, bool *use_fifos); /* --- Plugin handling --- */ extern struct tep_plugin_option trace_ftrace_options[]; diff --git a/lib/trace-cmd/trace-recorder.c b/lib/trace-cmd/trace-recorder.c index d57a5d6..bbba14c 100644 --- a/lib/trace-cmd/trace-recorder.c +++ b/lib/trace-cmd/trace-recorder.c @@ -8,6 +8,7 @@ #include #include #include +#include #include #include @@ -26,6 +27,8 @@ # define SPLICE_F_GIFT 8 #endif +#define POLL_TIMEOUT_MS 1000 + struct tracecmd_recorder { int fd; int fd1; @@ -40,6 +43,7 @@ struct tracecmd_recorder { int pages; int count; unsigned fd_flags; + unsigned trace_fd_flags; unsigned flags; }; @@ -127,6 +131,8 @@ tracecmd_create_buffer_recorder_fd2(int fd, int fd2, int cpu, unsigned flags, if (!(recorder->flags & TRACECMD_RECORD_BLOCK)) recorder->fd_flags |= SPLICE_F_NONBLOCK; + recorder->trace_fd_flags = SPLICE_F_MOVE; + /* Init to know what to free and release */ recorder->trace_fd = -1; recorder->brass[0] = -1; @@ -171,7 +177,8 @@ tracecmd_create_buffer_recorder_fd2(int fd, int fd2, int cpu, unsigned flags, goto out_free; } - if ((recorder->flags & TRACECMD_RECORD_NOSPLICE) == 0) { + if (!(recorder->flags & (TRACECMD_RECORD_NOSPLICE | + TRACECMD_RECORD_NOBRASS))) { ret = pipe(recorder->brass); if (ret < 0) goto out_free; @@ -380,7 +387,7 @@ static long splice_data(struct tracecmd_recorder *recorder) long ret; read = splice(recorder->trace_fd, NULL, recorder->brass[1], NULL, - recorder->pipe_size, SPLICE_F_MOVE); + recorder->pipe_size, recorder->trace_fd_flags); if (read < 0) { if (errno == EAGAIN || errno == EINTR || errno == ENOTCONN) return 0; @@ -409,6 +416,47 @@ static long splice_data(struct tracecmd_recorder *recorder) return total_read; } +/* + * Returns -1 on error. + * or bytes of data read. + */ +static long direct_splice_data(struct tracecmd_recorder *recorder) +{ + struct pollfd pfd = { + .fd = recorder->trace_fd, + .events = POLLIN, + }; + long read; + int ret; + + /* + * splice(2) in Linux used to not check O_NONBLOCK flag of pipe file + * descriptors before [1]. To avoid getting blocked in the splice(2) + * call below after the user had requested to stop tracing, we poll(2) + * here. This poll() is not necessary on newer kernels. + * + * [1] https://github.com/torvalds/linux/commit/ee5e001196d1345b8fee25925ff5f1d67936081e + */ + ret = poll(&pfd, 1, POLL_TIMEOUT_MS); + if (ret < 0) + return -1; + + if (!(pfd.revents | POLLIN)) + return 0; + + read = splice(recorder->trace_fd, NULL, recorder->fd, NULL, + recorder->pipe_size, recorder->fd_flags); + if (read < 0) { + if (errno == EAGAIN || errno == EINTR || errno == ENOTCONN) + return 0; + + warning("recorder error in splice input"); + return -1; + } + + return read; +} + /* * Returns -1 on error. * or bytes of data read. @@ -443,6 +491,17 @@ static long read_data(struct tracecmd_recorder *recorder) return r; } +static long move_data(struct tracecmd_recorder *recorder) +{ + if (recorder->flags & TRACECMD_RECORD_NOSPLICE) + return read_data(recorder); + + if (recorder->flags & TRACECMD_RECORD_NOBRASS) + return direct_splice_data(recorder); + + return splice_data(recorder); +} + static void set_nonblock(struct tracecmd_recorder *recorder) { long flags; @@ -465,10 +524,7 @@ long tracecmd_flush_recording(struct tracecmd_recorder *recorder) set_nonblock(recorder); do { - if (recorder->flags & TRACECMD_RECORD_NOSPLICE) - ret = read_data(recorder); - else - ret = splice_data(recorder); + ret = move_data(recorder); if (ret < 0) return ret; total += ret; @@ -513,10 +569,7 @@ int tracecmd_start_recording(struct tracecmd_recorder *recorder, unsigned long s read = 0; do { - if (recorder->flags & TRACECMD_RECORD_NOSPLICE) - ret = read_data(recorder); - else - ret = splice_data(recorder); + ret = move_data(recorder); if (ret < 0) return ret; read += ret; diff --git a/tracecmd/include/trace-local.h b/tracecmd/include/trace-local.h index 93da7da..29d0bf8 100644 --- a/tracecmd/include/trace-local.h +++ b/tracecmd/include/trace-local.h @@ -17,6 +17,7 @@ #define GUEST_PIPE_NAME "trace-pipe-cpu" #define GUEST_DIR_FMT "/var/lib/trace-cmd/virt/%s" #define GUEST_FIFO_FMT GUEST_DIR_FMT "/" GUEST_PIPE_NAME "%d" +#define VIRTIO_FIFO_FMT "/dev/virtio-ports/" GUEST_PIPE_NAME "%d" extern int debug; extern int quiet; @@ -100,7 +101,7 @@ void trace_usage(int argc, char **argv); int trace_record_agent(struct tracecmd_msg_handle *msg_handle, int cpus, int *fds, - int argc, char **argv); + int argc, char **argv, bool use_fifos); struct hook_list; @@ -214,6 +215,7 @@ struct buffer_instance { unsigned int cid; unsigned int port; int *fds; + bool use_fifos; }; extern struct buffer_instance top_instance; diff --git a/tracecmd/trace-agent.c b/tracecmd/trace-agent.c index 5e3a067..6cd6491 100644 --- a/tracecmd/trace-agent.c +++ b/tracecmd/trace-agent.c @@ -100,12 +100,38 @@ static void make_vsocks(int nr, int *fds, unsigned int *ports) } } +static int open_agent_fifos(int nr_cpus, int *fds) +{ + char path[PATH_MAX]; + int i, fd, ret; + + for (i = 0; i < nr_cpus; i++) { + snprintf(path, sizeof(path), VIRTIO_FIFO_FMT, i); + fd = open(path, O_WRONLY); + if (fd < 0) { + ret = -errno; + goto cleanup; + } + + fds[i] = fd; + } + + return 0; + +cleanup: + while (--i >= 0) + close(fds[i]); + + return ret; +} + static void agent_handle(int sd, int nr_cpus, int page_size) { struct tracecmd_msg_handle *msg_handle; unsigned int *ports; char **argv = NULL; int argc = 0; + bool use_fifos; int *fds; int ret; @@ -118,17 +144,22 @@ static void agent_handle(int sd, int nr_cpus, int page_size) if (!msg_handle) die("Failed to allocate message handle"); - ret = tracecmd_msg_recv_trace_req(msg_handle, &argc, &argv); + ret = tracecmd_msg_recv_trace_req(msg_handle, &argc, &argv, &use_fifos); if (ret < 0) die("Failed to receive trace request"); - make_vsocks(nr_cpus, fds, ports); + if (use_fifos && open_agent_fifos(nr_cpus, fds)) + use_fifos = false; + + if (!use_fifos) + make_vsocks(nr_cpus, fds, ports); - ret = tracecmd_msg_send_trace_resp(msg_handle, nr_cpus, page_size, ports); + ret = tracecmd_msg_send_trace_resp(msg_handle, nr_cpus, page_size, + ports, use_fifos); if (ret < 0) die("Failed to send trace response"); - trace_record_agent(msg_handle, nr_cpus, fds, argc, argv); + trace_record_agent(msg_handle, nr_cpus, fds, argc, argv, use_fifos); free(argv[0]); free(argv); diff --git a/tracecmd/trace-msg.c b/tracecmd/trace-msg.c index 69c7c5f..35a48c2 100644 --- a/tracecmd/trace-msg.c +++ b/tracecmd/trace-msg.c @@ -156,6 +156,10 @@ static int msg_write(int fd, struct tracecmd_msg *msg) return __do_write_check(fd, msg->buf, data_size); } +enum msg_trace_flags { + MSG_TRACE_USE_FIFOS = 1 << 0, +}; + static int make_tinit(struct tracecmd_msg_handle *msg_handle, struct tracecmd_msg *msg) { @@ -807,7 +811,7 @@ int tracecmd_msg_wait_close_resp(struct tracecmd_msg_handle *msg_handle) return tracecmd_msg_wait_for_cmd(msg_handle, MSG_CLOSE_RESP); } -static int make_trace_req(struct tracecmd_msg *msg, int argc, char **argv) +static int make_trace_req(struct tracecmd_msg *msg, int argc, char **argv, bool use_fifos) { size_t args_size = 0; char *p; @@ -817,6 +821,7 @@ static int make_trace_req(struct tracecmd_msg *msg, int argc, char **argv) args_size += strlen(argv[i]) + 1; msg->hdr.size = htonl(ntohl(msg->hdr.size) + args_size); + msg->trace_req.flags = use_fifos ? htonl(MSG_TRACE_USE_FIFOS) : htonl(0); msg->trace_req.argc = htonl(argc); msg->buf = calloc(args_size, 1); if (!msg->buf) @@ -830,13 +835,13 @@ static int make_trace_req(struct tracecmd_msg *msg, int argc, char **argv) } int tracecmd_msg_send_trace_req(struct tracecmd_msg_handle *msg_handle, - int argc, char **argv) + int argc, char **argv, bool use_fifos) { struct tracecmd_msg msg; int ret; tracecmd_msg_init(MSG_TRACE_REQ, &msg); - ret = make_trace_req(&msg, argc, argv); + ret = make_trace_req(&msg, argc, argv, use_fifos); if (ret < 0) return ret; @@ -849,7 +854,7 @@ int tracecmd_msg_send_trace_req(struct tracecmd_msg_handle *msg_handle, * free(argv); */ int tracecmd_msg_recv_trace_req(struct tracecmd_msg_handle *msg_handle, - int *argc, char ***argv) + int *argc, char ***argv, bool *use_fifos) { struct tracecmd_msg msg; char *p, *buf_end, **args; @@ -895,6 +900,7 @@ int tracecmd_msg_recv_trace_req(struct tracecmd_msg_handle *msg_handle, *argc = nr_args; *argv = args; + *use_fifos = ntohl(msg.trace_req.flags) & MSG_TRACE_USE_FIFOS; /* * On success we're passing msg.buf to the caller through argv[0] so we @@ -914,8 +920,8 @@ out: return ret; } -static int make_trace_resp(struct tracecmd_msg *msg, - int page_size, int nr_cpus, unsigned int *ports) +static int make_trace_resp(struct tracecmd_msg *msg, int page_size, int nr_cpus, + unsigned int *ports, bool use_fifos) { int data_size; @@ -926,6 +932,7 @@ static int make_trace_resp(struct tracecmd_msg *msg, write_uints(msg->buf, data_size, ports, nr_cpus); msg->hdr.size = htonl(ntohl(msg->hdr.size) + data_size); + msg->trace_resp.flags = use_fifos ? htonl(MSG_TRACE_USE_FIFOS) : htonl(0); msg->trace_resp.cpus = htonl(nr_cpus); msg->trace_resp.page_size = htonl(page_size); @@ -934,13 +941,13 @@ static int make_trace_resp(struct tracecmd_msg *msg, int tracecmd_msg_send_trace_resp(struct tracecmd_msg_handle *msg_handle, int nr_cpus, int page_size, - unsigned int *ports) + unsigned int *ports, bool use_fifos) { struct tracecmd_msg msg; int ret; tracecmd_msg_init(MSG_TRACE_RESP, &msg); - ret = make_trace_resp(&msg, page_size, nr_cpus, ports); + ret = make_trace_resp(&msg, page_size, nr_cpus, ports, use_fifos); if (ret < 0) return ret; @@ -949,7 +956,7 @@ int tracecmd_msg_send_trace_resp(struct tracecmd_msg_handle *msg_handle, int tracecmd_msg_recv_trace_resp(struct tracecmd_msg_handle *msg_handle, int *nr_cpus, int *page_size, - unsigned int **ports) + unsigned int **ports, bool *use_fifos) { struct tracecmd_msg msg; char *p, *buf_end; @@ -971,6 +978,7 @@ int tracecmd_msg_recv_trace_resp(struct tracecmd_msg_handle *msg_handle, goto out; } + *use_fifos = ntohl(msg.trace_resp.flags) & MSG_TRACE_USE_FIFOS; *nr_cpus = ntohl(msg.trace_resp.cpus); *page_size = ntohl(msg.trace_resp.page_size); *ports = calloc(*nr_cpus, sizeof(**ports)); diff --git a/tracecmd/trace-record.c b/tracecmd/trace-record.c index da63aef..6d5a59e 100644 --- a/tracecmd/trace-record.c +++ b/tracecmd/trace-record.c @@ -77,6 +77,8 @@ static int buffers; /* Clear all function filters */ static int clear_function_filters; +static bool no_fifos; + static char *host; /* Max size to let a per cpu file get */ @@ -2972,12 +2974,17 @@ create_recorder_instance(struct buffer_instance *instance, const char *file, int int fd; unsigned int flags; - fd = open_vsock(instance->cid, instance->client_ports[cpu]); + if (instance->use_fifos) + fd = instance->fds[cpu]; + else + fd = open_vsock(instance->cid, instance->client_ports[cpu]); if (fd < 0) die("Failed to connect to agent"); flags = recorder_flags; - if (!can_splice_read_vsock()) + if (instance->use_fifos) + flags |= TRACECMD_RECORD_NOBRASS; + else if (!can_splice_read_vsock()) flags |= TRACECMD_RECORD_NOSPLICE; return tracecmd_create_recorder_virt(file, cpu, flags, fd); } @@ -3032,10 +3039,14 @@ static int create_recorder(struct buffer_instance *instance, int cpu, char *path = NULL; int fd; - if (is_agent(instance)) - fd = do_accept(instance->fds[cpu]); - else + if (is_agent(instance)) { + if (instance->use_fifos) + fd = instance->fds[cpu]; + else + fd = do_accept(instance->fds[cpu]); + } else { fd = connect_port(host, instance->client_ports[cpu]); + } if (fd < 0) die("Failed connecting to client"); if (instance->name && !is_agent(instance)) @@ -3316,11 +3327,42 @@ static void finish_network(struct tracecmd_msg_handle *msg_handle) free(host); } +static int open_guest_fifos(const char *guest, int **fds) +{ + char path[PATH_MAX]; + int i, fd, flags; + + for (i = 0; ; i++) { + snprintf(path, sizeof(path), GUEST_FIFO_FMT ".out", guest, i); + + /* O_NONBLOCK so we don't wait for writers */ + fd = open(path, O_RDONLY | O_NONBLOCK); + if (fd < 0) + break; + + /* Success, now clear O_NONBLOCK */ + flags = fcntl(fd, F_GETFL); + fcntl(fd, F_SETFL, flags & ~O_NONBLOCK); + + *fds = realloc(*fds, i + 1); + (*fds)[i] = fd; + } + + return i; +} + static void connect_to_agent(struct buffer_instance *instance) { struct tracecmd_msg_handle *msg_handle; - int sd, ret, nr_cpus, page_size; + int sd, ret, nr_fifos, nr_cpus, page_size; unsigned int *ports; + int i, *fds = NULL; + bool use_fifos = false; + + if (!no_fifos) { + nr_fifos = open_guest_fifos(instance->name, &fds); + use_fifos = nr_fifos > 0; + } sd = open_vsock(instance->cid, instance->port); if (sd < 0) @@ -3331,15 +3373,33 @@ static void connect_to_agent(struct buffer_instance *instance) if (!msg_handle) die("Failed to allocate message handle"); - ret = tracecmd_msg_send_trace_req(msg_handle, instance->argc, instance->argv); + ret = tracecmd_msg_send_trace_req(msg_handle, instance->argc, + instance->argv, use_fifos); if (ret < 0) die("Failed to send trace request"); - ret = tracecmd_msg_recv_trace_resp(msg_handle, &nr_cpus, &page_size, &ports); + ret = tracecmd_msg_recv_trace_resp(msg_handle, &nr_cpus, &page_size, + &ports, &use_fifos); if (ret < 0) die("Failed to receive trace response"); - instance->client_ports = ports; + if (use_fifos) { + if (nr_cpus != nr_fifos) { + warning("number of FIFOs (%d) for guest %s differs " + "from number of virtual CPUs (%d)", + nr_fifos, instance->name, nr_cpus); + nr_cpus = nr_cpus < nr_fifos ? nr_cpus : nr_fifos; + } + free(ports); + instance->fds = fds; + } else { + for (i = 0; i < nr_fifos; i++) + close(fds[i]); + free(fds); + instance->client_ports = ports; + } + + instance->use_fifos = use_fifos; instance->cpu_count = nr_cpus; /* the msg_handle now points to the guest fd */ @@ -4868,6 +4928,7 @@ enum { OPT_funcstack = 254, OPT_date = 255, OPT_module = 256, + OPT_nofifos = 257, }; void trace_stop(int argc, char **argv) @@ -5138,6 +5199,7 @@ static void parse_record_options(int argc, {"date", no_argument, NULL, OPT_date}, {"func-stack", no_argument, NULL, OPT_funcstack}, {"nosplice", no_argument, NULL, OPT_nosplice}, + {"nofifos", no_argument, NULL, OPT_nofifos}, {"profile", no_argument, NULL, OPT_profile}, {"stderr", no_argument, NULL, OPT_stderr}, {"by-comm", no_argument, NULL, OPT_bycomm}, @@ -5429,6 +5491,9 @@ static void parse_record_options(int argc, case OPT_nosplice: recorder_flags |= TRACECMD_RECORD_NOSPLICE; break; + case OPT_nofifos: + no_fifos = true; + break; case OPT_profile: handle_init = trace_init_profile; ctx->instance->flags |= BUFFER_FL_PROFILE; @@ -5836,7 +5901,8 @@ void trace_record(int argc, char **argv) int trace_record_agent(struct tracecmd_msg_handle *msg_handle, int cpus, int *fds, - int argc, char **argv) + int argc, char **argv, + bool use_fifos) { struct common_record_context ctx; char **argv_plus; @@ -5862,6 +5928,7 @@ int trace_record_agent(struct tracecmd_msg_handle *msg_handle, return -EINVAL; ctx.instance->fds = fds; + ctx.instance->use_fifos = use_fifos; ctx.instance->flags |= BUFFER_FL_AGENT; ctx.instance->msg_handle = msg_handle; msg_handle->version = V3_PROTOCOL; -- 2.20.1