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Commit 0c9e6f63 authored by Lai Jiangshan's avatar Lai Jiangshan Committed by Frederic Weisbecker
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tracing: Simplify print_graph_cpu() 



print_graph_cpu() is little over-designed.

And "log10_all" may be wrong when there are holes in cpu_online_mask:
the max online cpu id > cpumask_weight(cpu_online_mask)

So change it by using a static column length for the cpu matching
nr_cpu_ids number of decimal characters.

Signed-off-by: default avatarLai Jiangshan <laijs@cn.fujitsu.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <4A6EEE5E.2000001@cn.fujitsu.com>
Signed-off-by: default avatarFrederic Weisbecker <fweisbec@gmail.com>
parent 1f9963cb

kernel/trace/trace_functions_graph.c

+4 −26
Original line number Diff line number Diff line
@@ -183,43 +183,19 @@ static void graph_trace_reset(struct trace_array *tr) 
	unregister_ftrace_graph();

}



static inline int log10_cpu(int nb)

{

	if (nb / 100)

		return 3;

	if (nb / 10)

		return 2;

	return 1;

}

static int max_bytes_for_cpu;



static enum print_line_t

print_graph_cpu(struct trace_seq *s, int cpu)

{

	int i;

	int ret;

	int log10_this = log10_cpu(cpu);

	int log10_all = log10_cpu(cpumask_weight(cpu_online_mask));





	/*

	 * Start with a space character - to make it stand out

	 * to the right a bit when trace output is pasted into

	 * email:

	 */

	ret = trace_seq_printf(s, " ");



	/*

	 * Tricky - we space the CPU field according to the max

	 * number of online CPUs. On a 2-cpu system it would take

	 * a maximum of 1 digit - on a 128 cpu system it would

	 * take up to 3 digits:

	 */

	for (i = 0; i < log10_all - log10_this; i++) {

		ret = trace_seq_printf(s, " ");

		if (!ret)

			return TRACE_TYPE_PARTIAL_LINE;

	}

	ret = trace_seq_printf(s, "%d) ", cpu);

	ret = trace_seq_printf(s, " %*d) ", max_bytes_for_cpu, cpu);

	if (!ret)

		return TRACE_TYPE_PARTIAL_LINE;
@@ -919,6 +895,8 @@ static struct tracer graph_trace __read_mostly = { 


static __init int init_graph_trace(void)

{

	max_bytes_for_cpu = snprintf(NULL, 0, "%d", nr_cpu_ids - 1);



	return register_tracer(&graph_trace);

}