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s390/wti: Add debugfs file to display missed grace periods per cpu

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Introduce a new debug file which allows to determine how many warning
track grace periods were missed on each CPU.
The new file can be found as /sys/kernel/debug/s390/wti

It is formatted as:
       CPU0       CPU1   [...]    CPUx
        xyz        xyz   [...]     xyz

Acked-by: Heiko Carstens <hca@linux.ibm.com>
Reviewed-by: Mete Durlu <meted@linux.ibm.com>
Signed-off-by: Tobias Huschle <huschle@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
This commit is contained in:
Tobias Huschle 2024-08-12 13:39:30 +02:00 • committed by Vasily Gorbik
parent 42419bcdfd
commit 307b675cf0
1 changed files with 25 additions and 0 deletions
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25
arch/s390/kernel/wti.c
View file

@ -5,6 +5,8 @@
* Copyright IBM Corp. 2023
*/
#include <linux/cpu.h>
#include <linux/debugfs.h>
#include <linux/kallsyms.h>
#include <linux/smpboot.h>
#include <linux/irq.h>
@ -117,6 +119,26 @@ static void wti_dbf_grace_period(struct wti_state *st)
wdi->missed++;
}
static int wti_show(struct seq_file *seq, void *v)
{
struct wti_state *st;
int cpu;
cpus_read_lock();
seq_puts(seq, " ");
for_each_online_cpu(cpu)
seq_printf(seq, "CPU%-8d", cpu);
seq_putc(seq, '\n');
for_each_online_cpu(cpu) {
st = per_cpu_ptr(&wti_state, cpu);
seq_printf(seq, " %10lu", st->dbg.missed);
}
seq_putc(seq, '\n');
cpus_read_unlock();
return 0;
}
DEFINE_SHOW_ATTRIBUTE(wti);
static void wti_thread_fn(unsigned int cpu)
{
struct wti_state *st = per_cpu_ptr(&wti_state, cpu);
@ -143,6 +165,7 @@ static struct smp_hotplug_thread wti_threads = {
static int __init wti_init(void)
{
struct sched_param wti_sched_param = { .sched_priority = MAX_RT_PRIO - 1 };
struct dentry *wti_dir;
struct wti_state *st;
int cpu, rc;
@ -168,6 +191,8 @@ static int __init wti_init(void)
rc = -EOPNOTSUPP;
goto out_subclass;
}
wti_dir = debugfs_create_dir("wti", arch_debugfs_dir);
debugfs_create_file("stat", 0400, wti_dir, NULL, &wti_fops);
wti_dbg = debug_register("wti", 1, 1, WTI_DBF_LEN);
if (!wti_dbg) {
rc = -ENOMEM;