Commit 795d6379 authored by Sebastian Andrzej Siewior's avatar Sebastian Andrzej Siewior Committed by Steven Rostedt (VMware)
Browse files

tracing: Make the space reserved for the pid wider 

For 64bit CONFIG_BASE_SMALL=0 systems PID_MAX_LIMIT is set by default to
4194304. During boot the kernel sets a new value based on number of CPUs
but no lower than 32768. It is 1024 per CPU so with 128 CPUs the default
becomes 131072 which needs six digits.
This value can be increased during run time but must not exceed the
initial upper limit.

Systemd sometime after v241 sets it to the upper limit during boot. The
result is that when the pid exceeds five digits, the trace output is a
little hard to read because it is no longer properly padded (same like
on big iron with 98+ CPUs).

Increase the pid padding to seven digits.

Link: https://lkml.kernel.org/r/20200904082331.dcdkrr3bkn3e4qlg@linutronix.de



Signed-off-by: default avatarSebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: default avatarSteven Rostedt (VMware) <rostedt@goodmis.org>
parent 478ece95

kernel/trace/trace.c

+19 −19
Original line number Diff line number Diff line
@@ -3819,7 +3819,7 @@ static void print_func_help_header_irq(struct array_buffer *buf, struct seq_file 
{

	bool tgid = flags & TRACE_ITER_RECORD_TGID;

	const char *space = "            ";

	int prec = tgid ? 10 : 2;

	int prec = tgid ? 12 : 2;



	print_event_info(buf, m);

kernel/trace/trace_output.c

+6 −6
Original line number Diff line number Diff line
@@ -497,7 +497,7 @@ lat_print_generic(struct trace_seq *s, struct trace_entry *entry, int cpu) 


	trace_find_cmdline(entry->pid, comm);



	trace_seq_printf(s, "%8.8s-%-5d %3d",

	trace_seq_printf(s, "%8.8s-%-7d %3d",

			 comm, entry->pid, cpu);



	return trace_print_lat_fmt(s, entry);
@@ -588,15 +588,15 @@ int trace_print_context(struct trace_iterator *iter) 


	trace_find_cmdline(entry->pid, comm);



	trace_seq_printf(s, "%16s-%-5d ", comm, entry->pid);

	trace_seq_printf(s, "%16s-%-7d ", comm, entry->pid);



	if (tr->trace_flags & TRACE_ITER_RECORD_TGID) {

		unsigned int tgid = trace_find_tgid(entry->pid);



		if (!tgid)

			trace_seq_printf(s, "(-----) ");

			trace_seq_printf(s, "(-------) ");

		else

			trace_seq_printf(s, "(%5d) ", tgid);

			trace_seq_printf(s, "(%7d) ", tgid);

	}



	trace_seq_printf(s, "[%03d] ", iter->cpu);
@@ -636,7 +636,7 @@ int trace_print_lat_context(struct trace_iterator *iter) 
		trace_find_cmdline(entry->pid, comm);



		trace_seq_printf(

			s, "%16s %5d %3d %d %08x %08lx ",

			s, "%16s %7d %3d %d %08x %08lx ",

			comm, entry->pid, iter->cpu, entry->flags,

			entry->preempt_count, iter->idx);

	} else {
@@ -917,7 +917,7 @@ static enum print_line_t trace_ctxwake_print(struct trace_iterator *iter, 
	S = task_index_to_char(field->prev_state);

	trace_find_cmdline(field->next_pid, comm);

	trace_seq_printf(&iter->seq,

			 " %5d:%3d:%c %s [%03d] %5d:%3d:%c %s\n",

			 " %7d:%3d:%c %s [%03d] %7d:%3d:%c %s\n",

			 field->prev_pid,

			 field->prev_prio,

			 S, delim,

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