[PATCH 2/2] sched/debug: adjust newlines for better alignment

From: Joe Lawrence
Date: Mon Mar 19 2018 - 14:36:13 EST


Scheduler debug stats include newlines that display out of alignment
when prefixed by timestamps. For example, the dmesg utility:

% echo t > /proc/sysrq-trigger
% dmesg
...
[ 83.124251]
runnable tasks:
S task PID tree-key switches prio wait-time
sum-exec sum-sleep
-----------------------------------------------------------------------------------------------------------

At the same time, some syslog utilities (like rsyslog by default) don't
like the additional newlines control characters, saving lines like this
to /var/log/messages:

Mar 16 16:02:29 localhost kernel: #012runnable tasks:#012 S task PID tree-key ...
^^^^ ^^^^
Clean these up by moving newline characters to their own SEQ_printf
invocation. This leaves the /proc/sched_debug unchanged, but brings the
entire output into alignment when prefixed:

% echo t > /proc/sysrq-trigger
% dmesg
...
[ 62.410368] runnable tasks:
[ 62.410368] S task PID tree-key switches prio wait-time sum-exec sum-sleep
[ 62.410369] -----------------------------------------------------------------------------------------------------------
[ 62.410369] I kworker/u12:0 5 1932.215593 332 120 0.000000 3.621252 0.000000 0 0 /

and no escaped control characters from rsyslog in /var/log/messages:

Mar 16 16:15:06 localhost kernel: runnable tasks:
Mar 16 16:15:06 localhost kernel: S task PID tree-key ...

Signed-off-by: Joe Lawrence <joe.lawrence@xxxxxxxxxx>
---
kernel/sched/debug.c | 27 ++++++++++++++++-----------
1 file changed, 16 insertions(+), 11 deletions(-)

diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c
index 50026aa2d81e..72c401b3b15c 100644
--- a/kernel/sched/debug.c
+++ b/kernel/sched/debug.c
@@ -501,12 +501,12 @@ static void print_rq(struct seq_file *m, struct rq *rq, int rq_cpu)
{
struct task_struct *g, *p;

- SEQ_printf(m,
- "\nrunnable tasks:\n"
- " S task PID tree-key switches prio"
- " wait-time sum-exec sum-sleep\n"
- "-------------------------------------------------------"
- "----------------------------------------------------\n");
+ SEQ_printf(m, "\n");
+ SEQ_printf(m, "runnable tasks:\n");
+ SEQ_printf(m, " S task PID tree-key switches prio"
+ " wait-time sum-exec sum-sleep\n");
+ SEQ_printf(m, "-------------------------------------------------------"
+ "----------------------------------------------------\n");

rcu_read_lock();
for_each_process_thread(g, p) {
@@ -527,9 +527,11 @@ void print_cfs_rq(struct seq_file *m, int cpu, struct cfs_rq *cfs_rq)
unsigned long flags;

#ifdef CONFIG_FAIR_GROUP_SCHED
- SEQ_printf(m, "\ncfs_rq[%d]:%s\n", cpu, task_group_path(cfs_rq->tg));
+ SEQ_printf(m, "\n");
+ SEQ_printf(m, "cfs_rq[%d]:%s\n", cpu, task_group_path(cfs_rq->tg));
#else
- SEQ_printf(m, "\ncfs_rq[%d]:\n", cpu);
+ SEQ_printf(m, "\n");
+ SEQ_printf(m, "cfs_rq[%d]:\n", cpu);
#endif
SEQ_printf(m, " .%-30s: %Ld.%06ld\n", "exec_clock",
SPLIT_NS(cfs_rq->exec_clock));
@@ -595,9 +597,11 @@ void print_cfs_rq(struct seq_file *m, int cpu, struct cfs_rq *cfs_rq)
void print_rt_rq(struct seq_file *m, int cpu, struct rt_rq *rt_rq)
{
#ifdef CONFIG_RT_GROUP_SCHED
- SEQ_printf(m, "\nrt_rq[%d]:%s\n", cpu, task_group_path(rt_rq->tg));
+ SEQ_printf(m, "\n");
+ SEQ_printf(m, "rt_rq[%d]:%s\n", cpu, task_group_path(rt_rq->tg));
#else
- SEQ_printf(m, "\nrt_rq[%d]:\n", cpu);
+ SEQ_printf(m, "\n");
+ SEQ_printf(m, "rt_rq[%d]:\n", cpu);
#endif

#define P(x) \
@@ -624,7 +628,8 @@ void print_dl_rq(struct seq_file *m, int cpu, struct dl_rq *dl_rq)
{
struct dl_bw *dl_bw;

- SEQ_printf(m, "\ndl_rq[%d]:\n", cpu);
+ SEQ_printf(m, "\n");
+ SEQ_printf(m, "dl_rq[%d]:\n", cpu);

#define PU(x) \
SEQ_printf(m, " .%-30s: %lu\n", #x, (unsigned long)(dl_rq->x))
--
1.8.3.1