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Subject[PATCH V4 5/5] trace-cmd/record: Add --virt option for record mode
From
Date
Add --virt option for record mode for a virtualization environment.
If we use this option on a guest, we can send trace data in low-overhead.
This is because guests can send trace data to a host without copying the data
by using splice(2).

The format is:

trace-cmd record --virt -e sched*

<Note>
The client using virtio-serial does not wait for the connection message
"tracecmd" from the server. The client sends the connection message
MSG_TCONNECT first.

<Restriction>
This feature can use from kernel-3.6 which supports splice_read for ftrace
and splice_write for virtio-serial.

Changes in V4: Rebase for current trace-cmd-v2.4
Add usage of --virt for record in trace-usage.c
Divide tracecmd_msg_connect_to_server() into two functions
(tracecmd_msg_connect_to_server() and
tracecmd_msg_send_init_data_virt(fd))
Changes in V3: Change _nw/_NW to _net/_NET

Signed-off-by: Yoshihiro YUNOMAE <yoshihiro.yunomae.ez@hitachi.com>
---
Documentation/trace-cmd-record.1.txt | 11 ++++-
trace-cmd.h | 4 +-
trace-msg.c | 79 +++++++++++++++++++++++++++++++---
trace-msg.h | 4 ++
trace-record.c | 71 ++++++++++++++++++++++++++++---
trace-usage.c | 3 +
6 files changed, 158 insertions(+), 14 deletions(-)

diff --git a/Documentation/trace-cmd-record.1.txt b/Documentation/trace-cmd-record.1.txt
index 9e63eb4..c0de074 100644
--- a/Documentation/trace-cmd-record.1.txt
+++ b/Documentation/trace-cmd-record.1.txt
@@ -258,6 +258,15 @@ OPTIONS
timestamp to gettimeofday which will allow wall time output from the
timestamps reading the created 'trace.dat' file.

+*--virt*::
+ This option is usded on a guest in a virtualization environment. If a host
+ is running "trace-cmd virt-server", this option is used to have the data
+ sent to the host with virtio-serial like *-N* option. (see also
+ trace-cmd-virt-server(1))
+
+ Note: This option is not supported with latency tracer plugins:
+ wakeup, wakeup_rt, irqsoff, preemptoff and preemptirqsoff
+
EXAMPLES
--------

@@ -320,7 +329,7 @@ SEE ALSO
--------
trace-cmd(1), trace-cmd-report(1), trace-cmd-start(1), trace-cmd-stop(1),
trace-cmd-extract(1), trace-cmd-reset(1), trace-cmd-split(1),
-trace-cmd-list(1), trace-cmd-listen(1)
+trace-cmd-list(1), trace-cmd-listen(1), trace-cmd-virt-server(1)

AUTHOR
------
diff --git a/trace-cmd.h b/trace-cmd.h
index c4e5beb..1c1b0c3 100644
--- a/trace-cmd.h
+++ b/trace-cmd.h
@@ -250,7 +250,9 @@ void tracecmd_stat_cpu(struct trace_seq *s, int cpu);
long tracecmd_flush_recording(struct tracecmd_recorder *recorder);

/* for clients */
-int tracecmd_msg_send_init_data(int fd);
+int tracecmd_msg_connect_to_server(int fd);
+int tracecmd_msg_send_init_data_net(int fd);
+int tracecmd_msg_send_init_data_virt(int fd);
int tracecmd_msg_metadata_send(int fd, char *buf, int size);
int tracecmd_msg_finish_sending_metadata(int fd);
void tracecmd_msg_send_close_msg(void);
diff --git a/trace-msg.c b/trace-msg.c
index 0d606dc..7ca31d6 100644
--- a/trace-msg.c
+++ b/trace-msg.c
@@ -30,6 +30,7 @@
#include <stdio.h>
#include <unistd.h>
#include <arpa/inet.h>
+#include <sys/stat.h>
#include <sys/types.h>
#include <linux/types.h>

@@ -72,6 +73,7 @@ int cpu_count;
static int psfd;
unsigned int page_size;
int *client_ports;
+int *virt_sfds;
bool send_metadata;

/* for server */
@@ -272,12 +274,20 @@ static int make_rinit(struct tracecmd_msg *msg)
return 0;
}

+static int make_error_msg(u32 len, struct tracecmd_msg *msg)
+{
+ bufcpy(msg, TRACECMD_MSG_HDR_LEN, errmsg, len);
+ return 0;
+}
+
static u32 tracecmd_msg_get_body_length(u32 cmd)
{
struct tracecmd_msg *msg;
u32 len = 0;

switch (cmd) {
+ case MSG_ERROR:
+ return ntohl(errmsg->size);
case MSG_RCONNECT:
return sizeof(msg->data.rconnect.str.size) + CONNECTION_MSGSIZE;
case MSG_TINIT:
@@ -305,6 +315,7 @@ static u32 tracecmd_msg_get_body_length(u32 cmd)
+ sizeof(msg->data.rinit.port_array);
case MSG_SENDMETA:
return TRACECMD_MSG_MAX_LEN - TRACECMD_MSG_HDR_LEN;
+ case MSG_TCONNECT:
case MSG_CLOSE:
case MSG_FINMETA:
break;
@@ -313,15 +324,18 @@ static u32 tracecmd_msg_get_body_length(u32 cmd)
return 0;
}

-static int tracecmd_msg_make_body(u32 cmd, struct tracecmd_msg *msg)
+static int tracecmd_msg_make_body(u32 cmd, u32 len, struct tracecmd_msg *msg)
{
switch (cmd) {
+ case MSG_ERROR:
+ return make_error_msg(len, msg);
case MSG_RCONNECT:
return make_rconnect(CONNECTION_MSG, CONNECTION_MSGSIZE, msg);
case MSG_TINIT:
return make_tinit(msg);
case MSG_RINIT:
return make_rinit(msg);
+ case MSG_TCONNECT:
case MSG_CLOSE:
case MSG_SENDMETA: /* meta data is not stored here. */
case MSG_FINMETA:
@@ -346,7 +360,7 @@ static int tracecmd_msg_create(u32 cmd, struct tracecmd_msg **msg)
if (ret < 0)
return ret;

- ret = tracecmd_msg_make_body(cmd, *msg);
+ ret = tracecmd_msg_make_body(cmd, len, *msg);
if (ret < 0)
free(*msg);

@@ -375,6 +389,12 @@ static int tracecmd_msg_send(int fd, u32 cmd)
return ret;
}

+static void tracecmd_msg_send_error(int fd, struct tracecmd_msg *msg)
+{
+ errmsg = msg;
+ tracecmd_msg_send(fd, MSG_ERROR);
+}
+
static int tracecmd_msg_read_extra(int fd, void *buf, u32 size, int *n)
{
int r = 0;
@@ -499,9 +519,10 @@ static int tracecmd_msg_send_and_wait_for_msg(int fd, u32 cmd, struct tracecmd_m
return 0;
}

-int tracecmd_msg_send_init_data(int fd)
+static int tracecmd_msg_send_init_data(int fd, bool net)
{
char buf[TRACECMD_MSG_MAX_LEN];
+ char path[PATH_MAX];
struct tracecmd_msg *msg;
int i, cpus;
int ret;
@@ -512,9 +533,24 @@ int tracecmd_msg_send_init_data(int fd)
return ret;

cpus = ntohl(msg->data.rinit.cpus);
- client_ports = malloc_or_die(sizeof(int) * cpus);
- for (i = 0; i < cpus; i++)
- client_ports[i] = ntohl(msg->data.rinit.port_array[i]);
+ if (net) {
+ client_ports = malloc_or_die(sizeof(int) * cpus);
+ for (i = 0; i < cpus; i++)
+ client_ports[i] =
+ ntohl(msg->data.rinit.port_array[i]);
+ } else {
+ virt_sfds = malloc_or_die(sizeof(int) * cpus);
+
+ /* Open data paths of virtio-serial */
+ for (i = 0; i < cpus; i++) {
+ snprintf(path, PATH_MAX, TRACE_PATH_CPU, i);
+ virt_sfds[i] = open(path, O_WRONLY);
+ if (virt_sfds[i] < 0) {
+ warning("Cannot open %s", TRACE_PATH_CPU, i);
+ return -errno;
+ }
+ }
+ }

/* Next, send meta data */
send_metadata = true;
@@ -522,6 +558,37 @@ int tracecmd_msg_send_init_data(int fd)
return 0;
}

+int tracecmd_msg_send_init_data_net(int fd)
+{
+ return tracecmd_msg_send_init_data(fd, true);
+}
+
+int tracecmd_msg_send_init_data_virt(int fd)
+{
+ return tracecmd_msg_send_init_data(fd, false);
+}
+
+int tracecmd_msg_connect_to_server(int fd)
+{
+ char buf[TRACECMD_MSG_MAX_LEN];
+ struct tracecmd_msg *msg;
+ int ret;
+
+ msg = (struct tracecmd_msg *)buf;
+ /* connect to a server */
+ ret = tracecmd_msg_send_and_wait_for_msg(fd, MSG_TCONNECT, msg);
+ if (ret < 0) {
+ if (ret == -EPROTONOSUPPORT)
+ goto error;
+ }
+
+ return ret;
+
+error:
+ tracecmd_msg_send_error(fd, msg);
+ return ret;
+}
+
static bool process_option(struct tracecmd_msg_opt *opt)
{
/* currently the only option we have is to us TCP */
diff --git a/trace-msg.h b/trace-msg.h
index b23e72b..502c1bf 100644
--- a/trace-msg.h
+++ b/trace-msg.h
@@ -2,6 +2,9 @@
#define _TRACE_MSG_H_

#include <stdbool.h>
+#define VIRTIO_PORTS "/dev/virtio-ports/"
+#define AGENT_CTL_PATH VIRTIO_PORTS "agent-ctl-path"
+#define TRACE_PATH_CPU VIRTIO_PORTS "trace-path-cpu%d"

#define UDP_MAX_PACKET (65536 - 20)
#define V2_MAGIC "677768\0"
@@ -17,6 +20,7 @@ extern int cpu_count;
extern unsigned int page_size;
extern int *client_ports;
extern bool send_metadata;
+extern int *virt_sfds;

/* for server */
extern bool done;
diff --git a/trace-record.c b/trace-record.c
index 79ce3a1..e56d294 100644
--- a/trace-record.c
+++ b/trace-record.c
@@ -77,6 +77,9 @@ static struct tracecmd_output *network_handle;
/* Max size to let a per cpu file get */
static int max_kb;

+struct tracecmd_output *virt_handle;
+static bool virt;
+
static int do_ptrace;

static int filter_task;
@@ -1787,6 +1790,9 @@ static int create_recorder(struct buffer_instance *instance, int cpu, int extrac
if (client_ports) {
connect_port(cpu);
recorder = tracecmd_create_recorder_fd(client_ports[cpu], cpu, recorder_flags);
+ } else if (virt_sfds) {
+ recorder = tracecmd_create_recorder_fd(virt_sfds[cpu], cpu,
+ recorder_flags);
} else {
file = get_temp_file(instance, cpu);
recorder = create_recorder_instance(instance, file, cpu);
@@ -1822,7 +1828,7 @@ static void check_first_msg_from_server(int fd)
die("server not tracecmd server");
}

-static void communicate_with_listener_v1(int fd)
+static void communicate_with_listener_v1_net(int fd)
{
char buf[BUFSIZ];
ssize_t n;
@@ -1885,9 +1891,9 @@ static void communicate_with_listener_v1(int fd)
}
}

-static void communicate_with_listener_v2(int fd)
+static void communicate_with_listener_v2_net(int fd)
{
- if (tracecmd_msg_send_init_data(fd) < 0)
+ if (tracecmd_msg_send_init_data_net(fd) < 0)
die("Cannot communicate with server");
}

@@ -1925,6 +1931,15 @@ static void check_protocol_version(int fd)
}
}

+static void communicate_with_listener_virt(int fd)
+{
+ if (tracecmd_msg_connect_to_server(fd) < 0)
+ die("Cannot communicate with server");
+
+ if (tracecmd_msg_send_init_data_virt(fd) < 0)
+ die("Cannot send init data");
+}
+
static void setup_network(void)
{
struct addrinfo hints;
@@ -1980,11 +1995,11 @@ again:
close(sfd);
goto again;
}
- communicate_with_listener_v2(sfd);
+ communicate_with_listener_v2_net(sfd);
}

if (proto_ver == V1_PROTOCOL)
- communicate_with_listener_v1(sfd);
+ communicate_with_listener_v1_net(sfd);

/* Now create the handle through this socket */
network_handle = tracecmd_create_init_fd_glob(sfd, listed_events);
@@ -1995,6 +2010,21 @@ again:
/* OK, we are all set, let'r rip! */
}

+static void setup_virtio(void)
+{
+ int fd;
+
+ fd = open(AGENT_CTL_PATH, O_RDWR);
+ if (fd < 0)
+ die("Cannot open %s", AGENT_CTL_PATH);
+
+ communicate_with_listener_virt(fd);
+
+ /* Now create the handle through this socket */
+ virt_handle = tracecmd_create_init_fd_glob(fd, listed_events);
+ tracecmd_msg_finish_sending_metadata(fd);
+}
+
static void finish_network(void)
{
if (proto_ver == V2_PROTOCOL)
@@ -2003,6 +2033,13 @@ static void finish_network(void)
free(host);
}

+static void finish_virt(void)
+{
+ tracecmd_msg_send_close_msg();
+ free(virt_handle);
+ free(virt_sfds);
+}
+
static void start_threads(void)
{
struct buffer_instance *instance;
@@ -2010,6 +2047,8 @@ static void start_threads(void)

if (host)
setup_network();
+ else if (virt)
+ setup_virtio();

/* make a thread for every CPU we have */
pids = malloc_or_die(sizeof(*pids) * cpu_count * (buffers + 1));
@@ -2079,6 +2118,9 @@ static void record_data(char *date2ts)
if (host) {
finish_network();
return;
+ } else if (virt) {
+ finish_virt();
+ return;
}

if (latency)
@@ -2732,6 +2774,7 @@ static void record_all_events(void)
}

enum {
+ OPT_virt = 252,
OPT_nosplice = 253,
OPT_funcstack = 254,
OPT_date = 255,
@@ -2885,6 +2928,7 @@ void trace_record (int argc, char **argv)
{"date", no_argument, NULL, OPT_date},
{"func-stack", no_argument, NULL, OPT_funcstack},
{"nosplice", no_argument, NULL, OPT_nosplice},
+ {"virt", no_argument, NULL, OPT_virt},
{"help", no_argument, NULL, '?'},
{NULL, 0, NULL, 0}
};
@@ -3015,6 +3059,8 @@ void trace_record (int argc, char **argv)
case 'o':
if (host)
die("-o incompatible with -N");
+ if (virt)
+ die("-o incompatible with --virt");
if (!record && !extract)
die("start does not take output\n"
"Did you mean 'record'?");
@@ -3046,6 +3092,8 @@ void trace_record (int argc, char **argv)
case 'N':
if (!record)
die("-N only available with record");
+ if (virt)
+ die("-N incompatible with --virt");
if (output)
die("-N incompatible with -o");
host = optarg;
@@ -3061,6 +3109,8 @@ void trace_record (int argc, char **argv)
instance->cpumask = optarg;
break;
case 't':
+ if (virt)
+ die("-t incompatible with --virt");
use_tcp = 1;
break;
case 'b':
@@ -3085,6 +3135,17 @@ void trace_record (int argc, char **argv)
case OPT_nosplice:
recorder_flags |= TRACECMD_RECORD_NOSPLICE;
break;
+ case OPT_virt:
+ if (!record)
+ die("--virt only available with record");
+ if (host)
+ die("--virt incompatible with -N");
+ if (output)
+ die("--virt incompatible with -o");
+ if (use_tcp)
+ die("--virt incompatible with -t");
+ virt = true;
+ break;
default:
usage(argv);
}
diff --git a/trace-usage.c b/trace-usage.c
index f96a5ba..45865f0 100644
--- a/trace-usage.c
+++ b/trace-usage.c
@@ -19,7 +19,7 @@ static struct usage_help usage_help[] = {
" %s record [-v][-e event [-f filter]][-p plugin][-F][-d][-D][-o file] \\\n"
" [-s usecs][-O option ][-l func][-g func][-n func] \\\n"
" [-P pid][-N host:port][-t][-r prio][-b size][-B buf][command ...]\n"
- " [-m max]\n"
+ " [-m max][--virt]\n"
" -e run command with event enabled\n"
" -f filter for previous -e event\n"
" -R trigger for previous -e event\n"
@@ -48,6 +48,7 @@ static struct usage_help usage_help[] = {
" -i do not fail if an event is not found\n"
" --func-stack perform a stack trace for function tracer\n"
" (use with caution)\n"
+ " --virt to connect to virt-server\n"
},
{
"start",


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