[PATCH] trace: Add an option to show tgids in trace output
From: Joel Fernandes
Date: Mon May 15 2017 - 21:46:33 EST
From: Jamie Gennis <jgennis@xxxxxxxxxx>
The tgids are tracked along side the saved_cmdlines tracking, and can be
included in trace output by enabling the 'print-tgid' trace option. This is
useful when doing post-processing of the trace data, as it allows events to be
grouped by tgid.
Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
Cc: kernel-team@xxxxxxxxxxx
Signed-off-by: Joel Fernandes <joelaf@xxxxxxxxxx>
---
kernel/trace/trace.c | 98 +++++++++++++++++++++++++++++++++++++++++++--
kernel/trace/trace.h | 4 +-
kernel/trace/trace_output.c | 14 ++++++-
3 files changed, 110 insertions(+), 6 deletions(-)
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index c4536c449021..aa0cb12892e7 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -1711,6 +1711,7 @@ void tracing_reset_all_online_cpus(void)
#define SAVED_CMDLINES_DEFAULT 128
#define NO_CMDLINE_MAP UINT_MAX
+static unsigned saved_tgids[SAVED_CMDLINES_DEFAULT];
static arch_spinlock_t trace_cmdline_lock = __ARCH_SPIN_LOCK_UNLOCKED;
struct saved_cmdlines_buffer {
unsigned map_pid_to_cmdline[PID_MAX_DEFAULT+1];
@@ -1949,7 +1950,7 @@ static int trace_save_cmdline(struct task_struct *tsk)
}
set_cmdline(idx, tsk->comm);
-
+ saved_tgids[idx] = tsk->tgid;
arch_spin_unlock(&trace_cmdline_lock);
return 1;
@@ -1992,6 +1993,25 @@ void trace_find_cmdline(int pid, char comm[])
preempt_enable();
}
+int trace_find_tgid(int pid)
+{
+ unsigned map;
+ int tgid;
+
+ preempt_disable();
+ arch_spin_lock(&trace_cmdline_lock);
+ map = savedcmd->map_pid_to_cmdline[pid];
+ if (map != NO_CMDLINE_MAP)
+ tgid = saved_tgids[map];
+ else
+ tgid = -1;
+
+ arch_spin_unlock(&trace_cmdline_lock);
+ preempt_enable();
+
+ return tgid;
+}
+
void tracing_record_cmdline(struct task_struct *tsk)
{
if (atomic_read(&trace_record_cmdline_disabled) || !tracing_is_on())
@@ -3226,6 +3246,13 @@ static void print_func_help_header(struct trace_buffer *buf, struct seq_file *m)
"# | | | | |\n");
}
+static void print_func_help_header_tgid(struct trace_buffer *buf, struct seq_file *m)
+{
+ print_event_info(buf, m);
+ seq_puts(m, "# TASK-PID TGID CPU# TIMESTAMP FUNCTION\n");
+ seq_puts(m, "# | | | | | |\n");
+}
+
static void print_func_help_header_irq(struct trace_buffer *buf, struct seq_file *m)
{
print_event_info(buf, m);
@@ -3238,6 +3265,18 @@ static void print_func_help_header_irq(struct trace_buffer *buf, struct seq_file
"# | | | |||| | |\n");
}
+static void print_func_help_header_irq_tgid(struct trace_buffer *buf, struct seq_file *m)
+{
+ print_event_info(buf, m);
+ seq_puts(m, "# _-----=> irqs-off\n");
+ seq_puts(m, "# / _----=> need-resched\n");
+ seq_puts(m, "# | / _---=> hardirq/softirq\n");
+ seq_puts(m, "# || / _--=> preempt-depth\n");
+ seq_puts(m, "# ||| / delay\n");
+ seq_puts(m, "# TASK-PID TGID CPU# |||| TIMESTAMP FUNCTION\n");
+ seq_puts(m, "# | | | | |||| | |\n");
+}
+
void
print_trace_header(struct seq_file *m, struct trace_iterator *iter)
{
@@ -3551,9 +3590,15 @@ void trace_default_header(struct seq_file *m)
} else {
if (!(trace_flags & TRACE_ITER_VERBOSE)) {
if (trace_flags & TRACE_ITER_IRQ_INFO)
- print_func_help_header_irq(iter->trace_buffer, m);
+ if (trace_flags & TRACE_ITER_TGID)
+ print_func_help_header_irq_tgid(iter->trace_buffer, m);
+ else
+ print_func_help_header_irq(iter->trace_buffer, m);
else
- print_func_help_header(iter->trace_buffer, m);
+ if (trace_flags & TRACE_ITER_TGID)
+ print_func_help_header_tgid(iter->trace_buffer, m);
+ else
+ print_func_help_header(iter->trace_buffer, m);
}
}
}
@@ -4894,6 +4939,50 @@ static void trace_insert_enum_map(struct module *mod,
}
static ssize_t
+tracing_saved_tgids_read(struct file *file, char __user *ubuf,
+ size_t cnt, loff_t *ppos)
+{
+ char *file_buf;
+ char *buf;
+ int len = 0;
+ int pid;
+ int i;
+
+ file_buf = kmalloc(SAVED_CMDLINES_DEFAULT*(16+1+16), GFP_KERNEL);
+ if (!file_buf)
+ return -ENOMEM;
+
+ buf = file_buf;
+
+ for (i = 0; i < SAVED_CMDLINES_DEFAULT; i++) {
+ int tgid;
+ int r;
+
+ pid = savedcmd->map_cmdline_to_pid[i];
+ if (pid == -1 || pid == NO_CMDLINE_MAP)
+ continue;
+
+ tgid = trace_find_tgid(pid);
+ r = sprintf(buf, "%d %d\n", pid, tgid);
+ buf += r;
+ len += r;
+ }
+
+ len = simple_read_from_buffer(ubuf, cnt, ppos,
+ file_buf, len);
+
+ kfree(file_buf);
+
+ return len;
+}
+
+static const struct file_operations tracing_saved_tgids_fops = {
+ .open = tracing_open_generic,
+ .read = tracing_saved_tgids_read,
+ .llseek = generic_file_llseek,
+};
+
+static ssize_t
tracing_set_trace_read(struct file *filp, char __user *ubuf,
size_t cnt, loff_t *ppos)
{
@@ -7619,6 +7708,9 @@ init_tracer_tracefs(struct trace_array *tr, struct dentry *d_tracer)
trace_create_file("trace_marker_raw", 0220, d_tracer,
tr, &tracing_mark_raw_fops);
+ trace_create_file("saved_tgids", 0444, d_tracer,
+ tr, &tracing_saved_tgids_fops);
+
trace_create_file("trace_clock", 0644, d_tracer, tr,
&trace_clock_fops);
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 291a1bca5748..f5bec38f40e0 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -697,6 +697,7 @@ static inline void __trace_stack(struct trace_array *tr, unsigned long flags,
extern u64 ftrace_now(int cpu);
extern void trace_find_cmdline(int pid, char comm[]);
+extern int trace_find_tgid(int pid);
extern void trace_event_follow_fork(struct trace_array *tr, bool enable);
#ifdef CONFIG_DYNAMIC_FTRACE
@@ -1110,7 +1111,8 @@ extern int trace_get_user(struct trace_parser *parser, const char __user *ubuf,
FUNCTION_FLAGS \
FGRAPH_FLAGS \
STACK_FLAGS \
- BRANCH_FLAGS
+ BRANCH_FLAGS \
+ C(TGID, "print-tgid"),
/*
* By defining C, we can make TRACE_FLAGS a list of bit names
diff --git a/kernel/trace/trace_output.c b/kernel/trace/trace_output.c
index 08f9bab8089e..00d65f87ad3d 100644
--- a/kernel/trace/trace_output.c
+++ b/kernel/trace/trace_output.c
@@ -581,11 +581,21 @@ int trace_print_context(struct trace_iterator *iter)
unsigned long long t;
unsigned long secs, usec_rem;
char comm[TASK_COMM_LEN];
+ int tgid;
trace_find_cmdline(entry->pid, comm);
- trace_seq_printf(s, "%16s-%-5d [%03d] ",
- comm, entry->pid, iter->cpu);
+ trace_seq_printf(s, "%16s-%-5d ", comm, entry->pid);
+
+ if (tr->trace_flags & TRACE_ITER_TGID) {
+ tgid = trace_find_tgid(entry->pid);
+ if (tgid < 0)
+ trace_seq_puts(s, "(-----) ");
+ else
+ trace_seq_printf(s, "(%5d) ", tgid);
+ }
+
+ trace_seq_printf(s, "[%03d] ", iter->cpu);
if (tr->trace_flags & TRACE_ITER_IRQ_INFO)
trace_print_lat_fmt(s, entry);
--
2.13.0.303.g4ebf302169-goog