* [PATCH] Modify the explanation and documentation related to watchdog thread
@ 2021-03-24 2:56 Wang Qing
2021-03-29 12:48 ` Petr Mladek
0 siblings, 1 reply; 2+ messages in thread
From: Wang Qing @ 2021-03-24 2:56 UTC (permalink / raw)
To: Jonathan Corbet, Wang Qing, Mauro Carvalho Chehab, Joe Perches,
Andrew Morton, Santosh Sivaraj, Petr Mladek, Andrey Ignatov,
Guilherme G. Piccoli, linux-doc, linux-kernel
"watchdog/%u" threads has be replaced by cpu_stop_work, So we need to modify
the explanation and documentation related to this.
Signed-off-by: Wang Qing <wangqing@vivo.com>
---
.../admin-guide/kernel-per-CPU-kthreads.rst | 20 --------------------
kernel/watchdog.c | 12 ++++--------
2 files changed, 4 insertions(+), 28 deletions(-)
diff --git a/Documentation/admin-guide/kernel-per-CPU-kthreads.rst b/Documentation/admin-guide/kernel-per-CPU-kthreads.rst
index 531f689..5e51ee5
--- a/Documentation/admin-guide/kernel-per-CPU-kthreads.rst
+++ b/Documentation/admin-guide/kernel-per-CPU-kthreads.rst
@@ -332,23 +332,3 @@ To reduce its OS jitter, do at least one of the following:
kthreads from being created in the first place. However, please
note that this will not eliminate OS jitter, but will instead
shift it to RCU_SOFTIRQ.
-
-Name:
- watchdog/%u
-
-Purpose:
- Detect software lockups on each CPU.
-
-To reduce its OS jitter, do at least one of the following:
-
-1. Build with CONFIG_LOCKUP_DETECTOR=n, which will prevent these
- kthreads from being created in the first place.
-2. Boot with "nosoftlockup=0", which will also prevent these kthreads
- from being created. Other related watchdog and softlockup boot
- parameters may be found in Documentation/admin-guide/kernel-parameters.rst
- and Documentation/watchdog/watchdog-parameters.rst.
-3. Echo a zero to /proc/sys/kernel/watchdog to disable the
- watchdog timer.
-4. Echo a large number of /proc/sys/kernel/watchdog_thresh in
- order to reduce the frequency of OS jitter due to the watchdog
- timer down to a level that is acceptable for your workload.
diff --git a/kernel/watchdog.c b/kernel/watchdog.c
index 7110906..d7fb4fb
--- a/kernel/watchdog.c
+++ b/kernel/watchdog.c
@@ -92,7 +92,7 @@ __setup("nmi_watchdog=", hardlockup_panic_setup);
* own hardlockup detector.
*
* watchdog_nmi_enable/disable can be implemented to start and stop when
- * softlockup watchdog threads start and stop. The arch must select the
+ * softlockup watchdog start and stop. The arch must select the
* SOFTLOCKUP_DETECTOR Kconfig.
*/
int __weak watchdog_nmi_enable(unsigned int cpu)
@@ -322,7 +322,7 @@ static DEFINE_PER_CPU(struct completion, softlockup_completion);
static DEFINE_PER_CPU(struct cpu_stop_work, softlockup_stop_work);
/*
- * The watchdog thread function - touches the timestamp.
+ * The watchdog feed function - touches the timestamp.
*
* It only runs once every sample_period seconds (4 seconds by
* default) to reset the softlockup timestamp. If this gets delayed
@@ -551,11 +551,7 @@ static void lockup_detector_reconfigure(void)
}
/*
- * Create the watchdog thread infrastructure and configure the detector(s).
- *
- * The threads are not unparked as watchdog_allowed_mask is empty. When
- * the threads are successfully initialized, take the proper locks and
- * unpark the threads in the watchdog_cpumask if the watchdog is enabled.
+ * Create the watchdog infrastructure and configure the detector(s).
*/
static __init void lockup_detector_setup(void)
{
@@ -621,7 +617,7 @@ void lockup_detector_soft_poweroff(void)
#ifdef CONFIG_SYSCTL
-/* Propagate any changes to the watchdog threads */
+/* Propagate any changes to the watchdog infrastructure */
static void proc_watchdog_update(void)
{
/* Remove impossible cpus to keep sysctl output clean. */
--
2.7.4
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] Modify the explanation and documentation related to watchdog thread
2021-03-24 2:56 [PATCH] Modify the explanation and documentation related to watchdog thread Wang Qing
@ 2021-03-29 12:48 ` Petr Mladek
0 siblings, 0 replies; 2+ messages in thread
From: Petr Mladek @ 2021-03-29 12:48 UTC (permalink / raw)
To: Wang Qing
Cc: Jonathan Corbet, Mauro Carvalho Chehab, Joe Perches,
Andrew Morton, Santosh Sivaraj, Andrey Ignatov,
Guilherme G. Piccoli, linux-doc, linux-kernel
On Wed 2021-03-24 10:56:39, Wang Qing wrote:
> "watchdog/%u" threads has be replaced by cpu_stop_work, So we need to modify
> the explanation and documentation related to this.
>
> Signed-off-by: Wang Qing <wangqing@vivo.com>
> ---
> .../admin-guide/kernel-per-CPU-kthreads.rst | 20 --------------------
> kernel/watchdog.c | 12 ++++--------
It would be nice to update also
Documentation/admin-guide/sysctl/kernel.rst
Documentation/admin-guide/lockup-watchdogs.rst
Anyway, the changes in this patch looks good. Feel free
to use:
Reviewed-by: Petr Mladek <pmladek@suse.com>
Best Regards,
Petr
^ permalink raw reply [flat|nested] 2+ messages in thread
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