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#define pr_fmt(fmt) "%s() " fmt "\n", __func__
#include <linux/debugfs.h>
#include <linux/generic-radix-tree.h>
#include <linux/init.h>
#include <linux/mmu_context.h>
#include <linux/rhashtable.h>
#include <linux/slab.h>
#include <linux/sort.h>
#include <linux/spinlock.h>
#include <linux/stacktrace.h>
#include <linux/time_stats.h>
#include "sched.h"
struct sched_wakeup_bt {
unsigned long d[10];
};
struct sched_wakeup_stats {
struct rhash_head hash;
struct sched_wakeup_bt bt;
struct time_stats stats;
};
static const struct rhashtable_params sched_wakeup_bt_params = {
.head_offset = offsetof(struct sched_wakeup_stats, hash),
.key_offset = offsetof(struct sched_wakeup_stats, bt),
.key_len = sizeof(struct sched_wakeup_bt),
};
static struct rhashtable stats_table;
static GENRADIX(struct sched_wakeup_stats *) stats_list;
static unsigned stats_nr;
static DEFINE_SPINLOCK(stats_lock);
static struct sched_wakeup_stats *__sched_wakeup_stats_new(struct sched_wakeup_bt *bt)
{
struct sched_wakeup_stats **slot =
genradix_ptr_alloc(&stats_list, stats_nr, GFP_ATOMIC);
if (!slot)
return ERR_PTR(-ENOMEM);
struct sched_wakeup_stats *s = kzalloc(sizeof(*s), GFP_ATOMIC);
if (!s)
return ERR_PTR(-ENOMEM);
s->bt = *bt;
int ret = rhashtable_lookup_insert_fast(&stats_table, &s->hash, sched_wakeup_bt_params);
if (unlikely(ret)) {
kfree(s);
return ret != -EEXIST ? ERR_PTR(ret) : NULL;
}
*slot = s;
stats_nr++;
return s;
}
static noinline struct sched_wakeup_stats *sched_wakeup_stats_new(struct sched_wakeup_bt *bt)
{
spin_lock(&stats_lock);
struct sched_wakeup_stats *s = __sched_wakeup_stats_new(bt);
spin_unlock(&stats_lock);
return s;
}
void sched_wakeup_backtrace(struct task_struct *task, u64 start_time)
{
if (!stats_table.tbl)
return;
if (task->__state & TASK_NOLOAD)
return;
u64 now = ktime_get_ns();
u64 duration = now - start_time;
if (duration < NSEC_PER_USEC)
return;
struct sched_wakeup_bt bt = {};
stack_trace_save_tsk(task, bt.d, ARRAY_SIZE(bt.d), 0);
struct sched_wakeup_stats *s;
while (!(s = rhashtable_lookup(&stats_table, &bt, sched_wakeup_bt_params) ?:
sched_wakeup_stats_new(&bt)))
;
if (likely(!IS_ERR(s)))
__time_stats_update(&s->stats, start_time, now);
}
struct sched_wakeup_iter {
loff_t pos;
size_t nr;
struct sched_wakeup_stats *d[];
};
#define cmp_int(l, r) ((l > r) - (l < r))
static int sched_wakeup_stats_cmp(const void *_l, const void *_r)
{
const struct sched_wakeup_stats * const *l = _l;
const struct sched_wakeup_stats * const *r = _r;
return -cmp_int((*l)->stats.total_duration, (*r)->stats.total_duration);
}
static void *sched_wakeup_start(struct seq_file *m, loff_t *pos)
{
unsigned nr = READ_ONCE(stats_nr);
struct sched_wakeup_iter *iter =
kzalloc(struct_size(iter, d, nr), GFP_KERNEL);
if (!iter)
return NULL;
iter->pos = *pos;
iter->nr = nr;
for (size_t i = 0; i < nr; i++)
iter->d[i] = *genradix_ptr(&stats_list, i);
sort(iter->d, nr, sizeof(iter->d[0]), sched_wakeup_stats_cmp, NULL);
return iter;
}
static void sched_wakeup_stop(struct seq_file *m, void *arg)
{
kfree(arg);
}
static void *sched_wakeup_next(struct seq_file *m, void *arg, loff_t *pos)
{
struct sched_wakeup_iter *iter = arg;
*pos = ++iter->pos;
if (iter->pos >= iter->nr)
return NULL;
return iter;
}
static int sched_wakeup_show(struct seq_file *m, void *arg)
{
struct sched_wakeup_iter *iter = arg;
struct sched_wakeup_stats *s = iter->d[iter->pos];
if (!s)
return 0;
char *bufp;
size_t n = seq_get_buf(m, &bufp);
struct seq_buf buf;
seq_buf_init(&buf, bufp, n);
if (iter->pos)
seq_buf_puts(&buf, "\n");
for (unsigned i = 0; i < ARRAY_SIZE(s->bt.d) && s->bt.d[i]; i++)
seq_buf_printf(&buf, "%pS\n", (void *) s->bt.d[i]);
time_stats_to_seq_buf(&buf, &s->stats, "startup", 0);
seq_commit(m, seq_buf_used(&buf));
return 0;
}
static const struct seq_operations sched_wakeup_ops = {
.start = sched_wakeup_start,
.stop = sched_wakeup_stop,
.next = sched_wakeup_next,
.show = sched_wakeup_show,
};
static int sched_wakeups_open(struct inode *inode, struct file *filp)
{
return seq_open(filp, &sched_wakeup_ops);
}
static const struct file_operations sched_wakeups_fops = {
.open = sched_wakeups_open,
.read = seq_read,
.llseek = seq_lseek,
.release = seq_release,
};
static int sched_wakeup_backtrace_init(void)
{
int ret = rhashtable_init(&stats_table, &sched_wakeup_bt_params);
WARN_ON(ret);
WARN_ON(!stats_table.tbl);
debugfs_create_file("wakeups", 0444, debugfs_sched, NULL, &sched_wakeups_fops);
return 0;
}
late_initcall(sched_wakeup_backtrace_init);
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