Commit 5b9f8ff7 authored by Valentin Schneider's avatar Valentin Schneider Committed by Ingo Molnar
Browse files

sched/debug: Output SD flag names rather than their values 



Decoding the output of /proc/sys/kernel/sched_domain/cpu*/domain*/flags has
always been somewhat annoying, as one needs to go fetch the bit -> name
mapping from the source code itself. This encoding can be saved in a script
somewhere, but that isn't safe from flags being added, removed or even
shuffled around.

What matters for debugging purposes is to get *which* flags are set in a
given domain, their associated value is pretty much meaningless.

Make the sd flags debug file output flag names.

Signed-off-by: default avatarValentin Schneider <valentin.schneider@arm.com>
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
Acked-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Link: https://lore.kernel.org/r/20200817113003.20802-7-valentin.schneider@arm.com
parent 65c5e253

kernel/sched/debug.c

+55 −1
Original line number Diff line number Diff line
@@ -245,6 +245,60 @@ set_table_entry(struct ctl_table *entry, 
	entry->proc_handler = proc_handler;

}



static int sd_ctl_doflags(struct ctl_table *table, int write,

			  void *buffer, size_t *lenp, loff_t *ppos)

{

	unsigned long flags = *(unsigned long *)table->data;

	size_t data_size = 0;

	size_t len = 0;

	char *tmp;

	int idx;



	if (write)

		return 0;



	for_each_set_bit(idx, &flags, __SD_FLAG_CNT) {

		char *name = sd_flag_debug[idx].name;



		/* Name plus whitespace */

		data_size += strlen(name) + 1;

	}



	if (*ppos > data_size) {

		*lenp = 0;

		return 0;

	}



	tmp = kcalloc(data_size + 1, sizeof(*tmp), GFP_KERNEL);

	if (!tmp)

		return -ENOMEM;



	for_each_set_bit(idx, &flags, __SD_FLAG_CNT) {

		char *name = sd_flag_debug[idx].name;



		len += snprintf(tmp + len, strlen(name) + 2, "%s ", name);

	}



	tmp += *ppos;

	len -= *ppos;



	if (len > *lenp)

		len = *lenp;

	if (len)

		memcpy(buffer, tmp, len);

	if (len < *lenp) {

		((char *)buffer)[len] = '\n';

		len++;

	}



	*lenp = len;

	*ppos += len;



	kfree(tmp);



	return 0;

}



static struct ctl_table *

sd_alloc_ctl_domain_table(struct sched_domain *sd)

{
@@ -258,7 +312,7 @@ sd_alloc_ctl_domain_table(struct sched_domain *sd) 
	set_table_entry(&table[2], "busy_factor",	  &sd->busy_factor,	    sizeof(int),  0644, proc_dointvec_minmax);

	set_table_entry(&table[3], "imbalance_pct",	  &sd->imbalance_pct,	    sizeof(int),  0644, proc_dointvec_minmax);

	set_table_entry(&table[4], "cache_nice_tries",	  &sd->cache_nice_tries,    sizeof(int),  0644, proc_dointvec_minmax);

	set_table_entry(&table[5], "flags",		  &sd->flags,		    sizeof(int),  0444, proc_dointvec_minmax);

	set_table_entry(&table[5], "flags",		  &sd->flags,		    sizeof(int),  0444, sd_ctl_doflags);

	set_table_entry(&table[6], "max_newidle_lb_cost", &sd->max_newidle_lb_cost, sizeof(long), 0644, proc_doulongvec_minmax);

	set_table_entry(&table[7], "name",		  sd->name,	       CORENAME_MAX_SIZE, 0444, proc_dostring);

	/* &table[8] is terminator */

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