From: paulmck@kernel.org
To: linux-kernel@vger.kernel.org
Cc: kernel-team@fb.com, john.stultz@linaro.org, tglx@linutronix.de,
sboyd@kernel.org, corbet@lwn.net, Mark.Rutland@arm.com,
maz@kernel.org, ak@linux.intel.com, clm@fb.com,
"Paul E. McKenney" <paulmck@kernel.org>
Subject: [PATCH clocksource 4/5] clocksource: Provide a module parameter to fuzz per-CPU clock checking
Date: Wed, 17 Feb 2021 13:29:22 -0800 [thread overview]
Message-ID: <20210217212923.21418-4-paulmck@kernel.org> (raw)
In-Reply-To: <20210217212814.GA14952@paulmck-ThinkPad-P72>
From: "Paul E. McKenney" <paulmck@kernel.org>
Code that checks for clock desynchronization must itself be tested, so
this commit creates a new clocksource.inject_delay_shift_percpu= kernel
boot parameter that adds or subtracts a large value from the check read,
using the specified bit of the CPU ID to determine whether to add or
to subtract.
Cc: John Stultz <john.stultz@linaro.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Stephen Boyd <sboyd@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Mark Rutland <Mark.Rutland@arm.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Andi Kleen <ak@linux.intel.com>
Reported-by: Chris Mason <clm@fb.com>
[ paulmck: Apply Randy Dunlap feedback. ]
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
---
Documentation/admin-guide/kernel-parameters.txt | 16 ++++++++++++++++
kernel/time/clocksource.c | 10 +++++++++-
2 files changed, 25 insertions(+), 1 deletion(-)
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 9965266..628e87f 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -593,6 +593,22 @@
times the value specified for inject_delay_freq
of consecutive non-delays.
+ clocksource.inject_delay_shift_percpu= [KNL]
+ Clocksource delay injection partitions the CPUs
+ into two sets, one whose clocks are moved ahead
+ and the other whose clocks are moved behind.
+ This kernel parameter selects the CPU-number
+ bit that determines which of these two sets the
+ corresponding CPU is placed into. For example,
+ setting this parameter to the value 4 will result
+ in the first set containing alternating groups
+ of 16 CPUs whose clocks are moved ahead, while
+ the second set will contain the rest of the CPUs,
+ whose clocks are moved behind.
+
+ The default value of -1 disables this type of
+ error injection.
+
clocksource.max_read_retries= [KNL]
Number of clocksource_watchdog() retries due to
external delays before the clock will be marked
diff --git a/kernel/time/clocksource.c b/kernel/time/clocksource.c
index 663bc53..df48416 100644
--- a/kernel/time/clocksource.c
+++ b/kernel/time/clocksource.c
@@ -190,6 +190,8 @@ static int inject_delay_freq;
module_param(inject_delay_freq, int, 0644);
static int inject_delay_run = 1;
module_param(inject_delay_run, int, 0644);
+static int inject_delay_shift_percpu = -1;
+module_param(inject_delay_shift_percpu, int, 0644);
static int max_read_retries = 3;
module_param(max_read_retries, int, 0644);
@@ -219,8 +221,14 @@ static cpumask_t cpus_behind;
static void clocksource_verify_one_cpu(void *csin)
{
struct clocksource *cs = (struct clocksource *)csin;
+ s64 delta = 0;
+ int sign;
- __this_cpu_write(csnow_mid, cs->read(cs));
+ if (inject_delay_shift_percpu >= 0) {
+ sign = ((smp_processor_id() >> inject_delay_shift_percpu) & 0x1) * 2 - 1;
+ delta = sign * NSEC_PER_SEC;
+ }
+ __this_cpu_write(csnow_mid, cs->read(cs) + delta);
}
static void clocksource_verify_percpu_wq(struct work_struct *unused)
--
2.9.5
next prev parent reply other threads:[~2021-02-17 21:31 UTC|newest]
Thread overview: 72+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-06 0:40 [PATCH RFC clocksource] Do not mark clocks unstable due to delays Paul E. McKenney
2021-01-06 0:41 ` [PATCH RFC clocksource 1/5] clocksource: Provide module parameters to inject delays in watchdog paulmck
2021-01-06 0:41 ` [PATCH RFC clocksource 2/5] clocksource: Retry clock read if long delays detected paulmck
2021-01-06 16:28 ` Rik van Riel
2021-01-06 19:53 ` Paul E. McKenney
2021-01-06 20:59 ` Rik van Riel
2021-01-06 0:41 ` [PATCH RFC clocksource 3/5] clocksource: Check per-CPU clock synchronization when marked unstable paulmck
2021-01-06 0:41 ` [PATCH RFC clocksource 4/5] clocksource: Provide a module parameter to fuzz per-CPU clock checking paulmck
2021-01-06 0:41 ` [PATCH RFC clocksource 5/5] clocksource: Do pairwise clock-desynchronization checking paulmck
2021-01-12 0:42 ` [PATCH v2 clocksource] Do not mark clocks unstable due to delays Paul E. McKenney
2021-01-12 0:45 ` [PATCH v2 clocksource 1/5] clocksource: Provide module parameters to inject delays in watchdog paulmck
2021-01-12 0:45 ` [PATCH v2 clocksource 2/5] clocksource: Retry clock read if long delays detected paulmck
2021-01-12 0:45 ` [PATCH v2 clocksource 3/5] clocksource: Check per-CPU clock synchronization when marked unstable paulmck
2021-01-12 0:45 ` [PATCH v2 clocksource 4/5] clocksource: Provide a module parameter to fuzz per-CPU clock checking paulmck
2021-01-12 0:45 ` [PATCH v2 clocksource 5/5] clocksource: Do pairwise clock-desynchronization checking paulmck
2021-02-02 17:04 ` [PATCH v3 clocksource] Do not mark clocks unstable due to delays Paul E. McKenney
2021-02-02 17:06 ` [PATCH clocksource 1/5] clocksource: Provide module parameters to inject delays in watchdog paulmck
2021-02-02 17:06 ` [PATCH clocksource 2/5] clocksource: Retry clock read if long delays detected paulmck
2021-02-02 17:06 ` [PATCH clocksource 3/5] clocksource: Check per-CPU clock synchronization when marked unstable paulmck
2021-02-02 17:06 ` [PATCH clocksource 4/5] clocksource: Provide a module parameter to fuzz per-CPU clock checking paulmck
2021-02-02 19:51 ` Randy Dunlap
2021-02-03 0:50 ` Paul E. McKenney
2021-02-03 1:31 ` Randy Dunlap
2021-02-03 1:40 ` Paul E. McKenney
2021-02-02 17:06 ` [PATCH clocksource 5/5] clocksource: Do pairwise clock-desynchronization checking paulmck
2021-02-17 21:28 ` [PATCH v3 clocksource] Do not mark clocks unstable due to delays Paul E. McKenney
2021-02-17 21:29 ` [PATCH clocksource 1/5] clocksource: Provide module parameters to inject delays in watchdog paulmck
2021-02-17 21:29 ` [PATCH clocksource 2/5] clocksource: Retry clock read if long delays detected paulmck
2021-02-17 21:29 ` [PATCH clocksource 3/5] clocksource: Check per-CPU clock synchronization when marked unstable paulmck
2021-02-17 21:29 ` paulmck [this message]
2021-02-17 21:29 ` [PATCH clocksource 5/5] clocksource: Do pairwise clock-desynchronization checking paulmck
2021-03-04 0:49 ` [PATCH v5 clocksource] Do not mark clocks unstable due to delays for v5.13 Paul E. McKenney
2021-03-04 0:53 ` [PATCH kernel/time 1/5] clocksource: Provide module parameters to inject delays in watchdog paulmck
2021-03-04 0:53 ` [PATCH kernel/time 2/5] clocksource: Retry clock read if long delays detected paulmck
2021-03-04 0:53 ` [PATCH kernel/time 3/5] clocksource: Check per-CPU clock synchronization when marked unstable paulmck
2021-03-04 0:53 ` [PATCH kernel/time 4/5] clocksource: Provide a module parameter to fuzz per-CPU clock checking paulmck
2021-03-04 0:53 ` [PATCH kernel/time 5/5] clocksource: Do pairwise clock-desynchronization checking paulmck
2021-04-02 20:29 ` [PATCH v5 clocksource] Do not mark clocks unstable due to delays for v5.13 Paul E. McKenney
2021-04-02 20:31 ` [PATCH v6 clocksource] Do not mark clocks unstable dueclocksource: Provide module parameters to inject delays in watchdog paulmck
2021-04-02 22:22 ` Thomas Gleixner
2021-04-02 22:37 ` Paul E. McKenney
2021-04-02 22:48 ` [PATCH v7 clocksource] Do not mark clocks unstable due to delays for v5.13 Paul E. McKenney
2021-04-02 22:49 ` [PATCH v7 clocksource 1/5] clocksource: Provide module parameters to inject delays in watchdog paulmck
2021-04-02 22:49 ` [PATCH v7 clocksource 2/5] clocksource: Retry clock read if long delays detected paulmck
2021-04-10 8:41 ` Thomas Gleixner
2021-04-10 23:50 ` Paul E. McKenney
2021-04-02 22:49 ` [PATCH v7 clocksource 3/5] clocksource: Check per-CPU clock synchronization when marked unstable paulmck
2021-04-10 9:00 ` Thomas Gleixner
2021-04-11 0:20 ` Paul E. McKenney
2021-04-11 10:33 ` Thomas Gleixner
2021-04-11 16:46 ` Paul E. McKenney
2021-04-12 4:21 ` Paul E. McKenney
2021-04-12 13:08 ` Thomas Gleixner
2021-04-12 18:20 ` Paul E. McKenney
2021-04-12 18:54 ` Thomas Gleixner
2021-04-12 19:57 ` Paul E. McKenney
2021-04-12 20:37 ` Thomas Gleixner
2021-04-12 23:18 ` Paul E. McKenney
2021-04-13 20:49 ` Thomas Gleixner
2021-04-14 4:48 ` Paul E. McKenney
2021-04-02 22:49 ` [PATCH v7 clocksource 4/5] clocksource: Provide a module parameter to fuzz per-CPU clock checking paulmck
2021-04-02 22:49 ` [PATCH v7 clocksource 5/5] clocksource: Do pairwise clock-desynchronization checking paulmck
2021-04-10 9:04 ` Thomas Gleixner
2021-04-11 0:21 ` Paul E. McKenney
2021-04-10 8:01 ` [PATCH v7 clocksource] Do not mark clocks unstable due to delays for v5.13 Thomas Gleixner
2021-04-10 23:26 ` Paul E. McKenney
2021-04-11 10:58 ` Thomas Gleixner
2021-04-11 16:50 ` Paul E. McKenney
2021-04-02 20:31 ` [PATCH v6 clocksource] Do not mark clocks unstable dueclocksource: Retry clock read if long delays detected paulmck
2021-04-02 20:31 ` [PATCH v6 clocksource] Do not mark clocks unstable dueclocksource: Check per-CPU clock synchronization when marked unstable paulmck
2021-04-02 20:31 ` [PATCH v6 clocksource] Do not mark clocks unstable dueclocksource: Provide a module parameter to fuzz per-CPU clock checking paulmck
2021-04-02 20:31 ` [PATCH v6 clocksource] Do not mark clocks unstable dueclocksource: Do pairwise clock-desynchronization checking paulmck
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