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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: Valentin Schneider <valentin.schneider@arm.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: https://lore.kernel.org/r/20200817113003.20802-7-valentin.schneider@arm.com
This commit is contained in:
Valentin Schneider 2020-08-17 12:29:52 +01:00 committed by Ingo Molnar
parent 65c5e25316
commit 5b9f8ff7b3
1 changed files with 55 additions and 1 deletions
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56
kernel/sched/debug.c
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@ -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 */