Now blk tracer could output cgroup info for trace actions and
trace messages, but there is no per-device API for it and it
can only be turned on globally by writing trace_options file
under /sys/kernel/debug/tracing.
Add option g/group to save cgroup info in trace file. Implement it
by writing "blk_cgroup" to trace_options file before tracing starts,
and writing "noblk_cgroup" to trace_options file after tracing stops.
Signed-off-by: Hou Tao <houtao1@xxxxxxxxxx>
---
blktrace.c | 144 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
doc/blktrace.8 | 9 +++-
2 files changed, 151 insertions(+), 2 deletions(-)
diff --git a/blktrace.c b/blktrace.c
index e048f68..56aa9c9 100644
--- a/blktrace.c
+++ b/blktrace.c
@@ -282,6 +282,7 @@ static int act_mask = ~0U;
static int kill_running_trace;
static int stop_watch;
static int piped_output;
+static int save_cgroup_info;
static char *debugfs_path = "/sys/kernel/debug";
static char *output_name;
@@ -328,7 +329,7 @@ static int *cl_fds;
static int (*handle_pfds)(struct tracer *, int, int);
static int (*handle_list)(struct tracer_devpath_head *, struct list_head *);
-#define S_OPTS "d:a:A:r:o:kw:vVb:n:D:lh:p:sI:"
+#define S_OPTS "d:a:A:r:o:kw:vVb:n:D:lh:p:sI:g"
static struct option l_opts[] = {
{
.name = "dev",
@@ -433,6 +434,12 @@ static struct option l_opts[] = {
.val = 's'
},
{
+ .name = "cgroup",
+ .has_arg = no_argument,
+ .flag = NULL,
+ .val = 'g',
+ },
+ {
.name = NULL,
}
};
@@ -446,6 +453,7 @@ static char usage_str[] = "\n\n" \
"[ -a <action field> | --act-mask=<action field>]\n" \
"[ -A <action mask> | --set-mask=<action mask>]\n" \
"[ -b <size> | --buffer-size]\n" \
+ "[ -g | --cgroup]\n" \
"[ -n <number> | --num-sub-buffers=<number>]\n" \
"[ -l | --listen]\n" \
"[ -h <hostname> | --host=<hostname>]\n" \
@@ -463,6 +471,7 @@ static char usage_str[] = "\n\n" \
"\t-a Only trace specified actions. See documentation\n" \
"\t-A Give trace mask as a single value. See documentation\n" \
"\t-b Sub buffer size in KiB (default 512)\n" \
+ "\t-g Save io cgroup info in trace\n" \
"\t-n Number of sub buffers (default 4)\n" \
"\t-l Run in network listen mode (blktrace server)\n" \
"\t-h Run in network client mode, connecting to the given host\n" \
@@ -2010,6 +2019,125 @@ static void wait_tracers(void)
get_all_drops();
}
+static int read_oneline_tfile(const char *name, char *buf, size_t len)
+{
+ char fn[MAXPATHLEN];
+ int fd;
+ ssize_t rcnt;
+
+ snprintf(fn, sizeof(fn), "%s/tracing/%s", debugfs_path, name);
+ fd = my_open(fn, O_RDONLY);
+ if (fd < 0) {
+ fprintf(stderr, "Could not open %s: %d/%s\n",
+ fn, errno, strerror(errno));
+ return -1;
+ }
+
+ /* -1 for the trailing \0 */
+ rcnt = read(fd, buf, len - 1);
+ if (rcnt >= 0) {
+ if (rcnt > 0 && buf[rcnt - 1] == '\n')
+ rcnt--;
+ buf[rcnt] = '\0';
+ } else {
+ fprintf(stderr, "Could not read %s: %d/%s\n",
+ fn, errno, strerror(errno));
+ }
+
+ close(fd);
+
+ return rcnt >= 0 ? 0 : -1;
+}
+
+static int write_tfile(const char *name, const char *str)
+{
+ char fn[MAXPATHLEN];
+ int fd;
+ size_t len;
+ ssize_t wcnt;
+
+ snprintf(fn, sizeof(fn), "%s/tracing/%s", debugfs_path, name);
+ fd = my_open(fn, O_WRONLY);
+ if (fd < 0) {
+ fprintf(stderr, "Could not open %s for write: %d/%s\n",
+ fn, errno, strerror(errno));
+ return -1;
+ }
+
+ len = strlen(str);
+ wcnt = write(fd, str, len);
+ if (wcnt < 0)
+ fprintf(stderr, "Could not write %s to %s: %d/%s\n",
+ str, fn, errno, strerror(errno));
+ else if ((size_t)wcnt != len)
+ fprintf(stderr, "Incomplete write (%zu/%zu) to %s: %d/%s\n",
+ (size_t)wcnt, len, fn, errno, strerror(errno));
+
+ close(fd);
+
+ return ((size_t)wcnt == len) ? 0 : -1;
+}
+
+static void restore_tracer(const char *tracer, int tracing_on)
+{
+ write_tfile("current_tracer", tracer);
+ if (tracing_on)
+ write_tfile("tracing_on", "1");
+}
+
+static int switch_tracer(const char *tracer, int *old_tracing_on)
+{
+ int err;
+ char buf[4];
+ int tracing_on;
+
+ err = read_oneline_tfile("tracing_on", buf, sizeof(buf));
+ if (err)
+ goto out;
+
+ tracing_on = atoi(buf);
+ if (tracing_on) {
+ err = write_tfile("tracing_on", "0");
+ if (err)
+ goto out;
+ }
+
+ err = write_tfile("current_tracer", tracer);
+ if (err)
+ goto restore_out;
+
+ *old_tracing_on = tracing_on;
+
+ return 0;
+
+restore_out:
+ if (tracing_on)
+ write_tfile("tracing_on", "1");
+out:
+ return -1;
+}
+
+static int set_blk_tracer_opt(const char *opt)
+{
+ int err;
+ char tracer[32];
+ int tracing_on = 0;
+
+ err = read_oneline_tfile("current_tracer", tracer, sizeof(tracer));
+ if (err)
+ return -1;
+
+ if (strcmp(tracer, "blk") && switch_tracer("blk", &tracing_on))
+ return -1;
+
+ err = write_tfile("trace_options", opt);
+
+ if (strcmp(tracer, "blk"))
+ restore_tracer(tracer, tracing_on);
+
+ return !err ? 0 : -1;
+}
+
static void exit_tracing(void)
{
signal(SIGINT, SIG_IGN);
@@ -2021,6 +2149,10 @@ static void exit_tracing(void)
wait_tracers();
del_tracers();
rel_devpaths();
+
+ if (save_cgroup_info) {
+ set_blk_tracer_opt("noblk_cgroup");
+ }
}
static void handle_sigint(__attribute__((__unused__)) int sig)
@@ -2131,6 +2263,10 @@ static int handle_args(int argc, char *argv[])
return 1;
break;
+ case 'g':
+ save_cgroup_info = 1;
+ break;
+
case 'I': {
char dev_line[256];
FILE *ifp = my_fopen(optarg, "r");
@@ -2681,6 +2817,12 @@ static int run_tracers(void)
if (net_mode == Net_client)
printf("blktrace: connecting to %s\n", hostname);
+ if (save_cgroup_info && set_blk_tracer_opt("blk_cgroup")) {
+ /* No need to disable opt "blk_cgroup" */
+ save_cgroup_info = 0;
+ return 1;
+ }
+
if (setup_buts())
return 1;
diff --git a/doc/blktrace.8 b/doc/blktrace.8
index 820b03a..861c54a 100644
--- a/doc/blktrace.8
+++ b/doc/blktrace.8
@@ -6,7 +6,7 @@ blktrace \- generate traces of the i/o traffic on block devices
.SH SYNOPSIS
-.B blktrace \-d \fIdev\fR [ \-r \fIdebugfs_path\fR ] [ \-o \fIoutput\fR ] [ \-w \fItime\fR ] [ \-a \fIaction\fR ] [ \-A \fIaction_mask\fR ] [ \-v ]
+.B blktrace \-d \fIdev\fR [ \-r \fIdebugfs_path\fR ] [ \-o \fIoutput\fR ] [ \-w \fItime\fR ] [ \-a \fIaction\fR ] [ \-A \fIaction_mask\fR ] [ \-g ] [ \-v ]
.br
@@ -103,6 +103,13 @@ buffer size is 512KiB.
Adds \fIdev\fR as a device to trace
.RE
+\-g
+.br
+\-\-cgroup
+.RS
+Save io cgroup info in trace
+.RE
+
\-I \fIfile\fR
.br
\-\-input\-devs=\fIfile\fR
--
2.9.5
--
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