* [PATCH V2,RESEND 2/4] doc: watchdog: Delete the explanation about "watchdog/%u".
2021-04-29 9:04 [PATCH V2,RESEND 1/4] kernel: watchdog: Modify the explanation related to watchdog thread Wang Qing
@ 2021-04-29 9:04 ` Wang Qing
2021-04-29 9:04 ` [PATCH V2,RESEND 3/4] doc: watchdog: Modify the explanation related to watchdog thread Wang Qing
` (2 subsequent siblings)
3 siblings, 0 replies; 6+ messages in thread
From: Wang Qing @ 2021-04-29 9:04 UTC (permalink / raw)
To: Jonathan Corbet, Wang Qing, Mauro Carvalho Chehab, Joe Perches,
Stephen Kitt, Andrew Morton, Kees Cook, Randy Dunlap,
Guilherme G. Piccoli, Qais Yousef, Petr Mladek, Santosh Sivaraj,
Vlastimil Babka, linux-doc, linux-kernel,
Mathieu Chouquet-Stringer
"watchdog/%u" threads has be replaced by cpu_stop_work. The current description
is extremely misleading, so delete the explanation about "watchdog/%u".
Signed-off-by: Wang Qing <wangqing@vivo.com>
---
.../admin-guide/kernel-per-CPU-kthreads.rst | 20 --------------------
1 file changed, 20 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.
--
2.7.4
^ permalink raw reply related [flat|nested] 6+ messages in thread
* [PATCH V2,RESEND 3/4] doc: watchdog: Modify the explanation related to watchdog thread
2021-04-29 9:04 [PATCH V2,RESEND 1/4] kernel: watchdog: Modify the explanation related to watchdog thread Wang Qing
2021-04-29 9:04 ` [PATCH V2,RESEND 2/4] doc: watchdog: Delete the explanation about "watchdog/%u" Wang Qing
@ 2021-04-29 9:04 ` Wang Qing
2021-04-29 9:04 ` [PATCH V2,RESEND 4/4] doc: watchdog: Modify the doc related to "watchdog/%u" Wang Qing
2021-04-29 9:29 ` [PATCH V2,RESEND 1/4] kernel: watchdog: Modify the explanation related to watchdog thread Petr Mladek
3 siblings, 0 replies; 6+ messages in thread
From: Wang Qing @ 2021-04-29 9:04 UTC (permalink / raw)
To: Jonathan Corbet, Wang Qing, Mauro Carvalho Chehab, Joe Perches,
Stephen Kitt, Andrew Morton, Kees Cook, Randy Dunlap,
Guilherme G. Piccoli, Qais Yousef, Petr Mladek, Santosh Sivaraj,
Vlastimil Babka, linux-doc, linux-kernel, Lepton Wu
"watchdog/%u" threads has be replaced by cpu_stop_work. The current
description is extremely misleading.
Signed-off-by: Wang Qing <wangqing@vivo.com>
---
Documentation/admin-guide/lockup-watchdogs.rst | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/Documentation/admin-guide/lockup-watchdogs.rst b/Documentation/admin-guide/lockup-watchdogs.rst
index 290840c..3e09284
--- a/Documentation/admin-guide/lockup-watchdogs.rst
+++ b/Documentation/admin-guide/lockup-watchdogs.rst
@@ -39,7 +39,7 @@ in principle, they should work in any architecture where these
subsystems are present.
A periodic hrtimer runs to generate interrupts and kick the watchdog
-task. An NMI perf event is generated every "watchdog_thresh"
+job. An NMI perf event is generated every "watchdog_thresh"
(compile-time initialized to 10 and configurable through sysctl of the
same name) seconds to check for hardlockups. If any CPU in the system
does not receive any hrtimer interrupt during that time the
@@ -47,7 +47,7 @@ does not receive any hrtimer interrupt during that time the
generate a kernel warning or call panic, depending on the
configuration.
-The watchdog task is a high priority kernel thread that updates a
+The watchdog job runs in a stop scheduling thread that updates a
timestamp every time it is scheduled. If that timestamp is not updated
for 2*watchdog_thresh seconds (the softlockup threshold) the
'softlockup detector' (coded inside the hrtimer callback function)
--
2.7.4
^ permalink raw reply related [flat|nested] 6+ messages in thread
* [PATCH V2,RESEND 4/4] doc: watchdog: Modify the doc related to "watchdog/%u"
2021-04-29 9:04 [PATCH V2,RESEND 1/4] kernel: watchdog: Modify the explanation related to watchdog thread Wang Qing
2021-04-29 9:04 ` [PATCH V2,RESEND 2/4] doc: watchdog: Delete the explanation about "watchdog/%u" Wang Qing
2021-04-29 9:04 ` [PATCH V2,RESEND 3/4] doc: watchdog: Modify the explanation related to watchdog thread Wang Qing
@ 2021-04-29 9:04 ` Wang Qing
2021-04-29 9:29 ` [PATCH V2,RESEND 1/4] kernel: watchdog: Modify the explanation related to watchdog thread Petr Mladek
3 siblings, 0 replies; 6+ messages in thread
From: Wang Qing @ 2021-04-29 9:04 UTC (permalink / raw)
To: Jonathan Corbet, Wang Qing, Mauro Carvalho Chehab, Joe Perches,
Stephen Kitt, Andrew Morton, Kees Cook, Randy Dunlap,
Guilherme G. Piccoli, Qais Yousef, Petr Mladek, Santosh Sivaraj,
Vlastimil Babka, linux-doc, linux-kernel
"watchdog/%u" threads has be replaced by cpu_stop_work. The current
description is extremely misleading.
---
Documentation/admin-guide/sysctl/kernel.rst | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)
diff --git a/Documentation/admin-guide/sysctl/kernel.rst b/Documentation/admin-guide/sysctl/kernel.rst
index 1d56a6b..32b0791
--- a/Documentation/admin-guide/sysctl/kernel.rst
+++ b/Documentation/admin-guide/sysctl/kernel.rst
@@ -1282,11 +1282,11 @@ This parameter can be used to control the soft lockup detector.
= =================================
The soft lockup detector monitors CPUs for threads that are hogging the CPUs
-without rescheduling voluntarily, and thus prevent the 'watchdog/N' threads
-from running. The mechanism depends on the CPUs ability to respond to timer
-interrupts which are needed for the 'watchdog/N' threads to be woken up by
-the watchdog timer function, otherwise the NMI watchdog — if enabled — can
-detect a hard lockup condition.
+without rescheduling voluntarily, and thus prevent the 'migration/N' threads
+from running, causing the watchdog work fail to execute. The mechanism depends
+on the CPUs ability to respond to timer interrupts which are needed for the
+watchdog work to be queued by the watchdog timer function, otherwise the NMI
+watchdog — if enabled — can detect a hard lockup condition.
stack_erasing
--
2.7.4
^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH V2,RESEND 1/4] kernel: watchdog: Modify the explanation related to watchdog thread
2021-04-29 9:04 [PATCH V2,RESEND 1/4] kernel: watchdog: Modify the explanation related to watchdog thread Wang Qing
` (2 preceding siblings ...)
2021-04-29 9:04 ` [PATCH V2,RESEND 4/4] doc: watchdog: Modify the doc related to "watchdog/%u" Wang Qing
@ 2021-04-29 9:29 ` Petr Mladek
2021-05-09 23:29 ` Andrew Morton
3 siblings, 1 reply; 6+ messages in thread
From: Petr Mladek @ 2021-04-29 9:29 UTC (permalink / raw)
To: Wang Qing, Andrew Morton
Cc: Jonathan Corbet, Mauro Carvalho Chehab, Joe Perches,
Stephen Kitt, Kees Cook, Randy Dunlap, Guilherme G. Piccoli,
Qais Yousef, Santosh Sivaraj, Vlastimil Babka, linux-doc,
linux-kernel
On Thu 2021-04-29 17:04:25, Wang Qing wrote:
> The watchdog thread has been replaced by cpu_stop_work, modify the
> explanation related.
>
> Signed-off-by: Wang Qing <wangqing@vivo.com>
You should have added my Reviewed-by when resending the patchset.
Anyway, for all four patches:
Reviewed-by: Petr Mladek <pmladek@suse.com>
Andrew, would you take it via -mm tree?
Best Regards,
Petr
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH V2,RESEND 1/4] kernel: watchdog: Modify the explanation related to watchdog thread
2021-04-29 9:29 ` [PATCH V2,RESEND 1/4] kernel: watchdog: Modify the explanation related to watchdog thread Petr Mladek
@ 2021-05-09 23:29 ` Andrew Morton
0 siblings, 0 replies; 6+ messages in thread
From: Andrew Morton @ 2021-05-09 23:29 UTC (permalink / raw)
To: Petr Mladek
Cc: Wang Qing, Jonathan Corbet, Mauro Carvalho Chehab, Joe Perches,
Stephen Kitt, Kees Cook, Randy Dunlap, Guilherme G. Piccoli,
Qais Yousef, Santosh Sivaraj, Vlastimil Babka, linux-doc,
linux-kernel
On Thu, 29 Apr 2021 11:29:31 +0200 Petr Mladek <pmladek@suse.com> wrote:
> On Thu 2021-04-29 17:04:25, Wang Qing wrote:
> > The watchdog thread has been replaced by cpu_stop_work, modify the
> > explanation related.
> >
> > Signed-off-by: Wang Qing <wangqing@vivo.com>
>
> You should have added my Reviewed-by when resending the patchset.
> Anyway, for all four patches:
>
> Reviewed-by: Petr Mladek <pmladek@suse.com>
>
> Andrew, would you take it via -mm tree?
Sure. I dropped "[2/4] doc: watchdog: Delete the explanation about
"watchdog/%u"" because someone already did that.
^ permalink raw reply [flat|nested] 6+ messages in thread