[PATCH clocksource 3/6] clocksource: Improve read-back-delay message

Paul E. McKenney
2023-01-05T01:07:27Z

When cs_watchdog_read() is unable to get a qualifying clocksource read
within the limit set by max_cswd_read_retries, it prints a message
and marks the clocksource under test as unstable. But that message is
unclear to anyone unfamiliar with the code:

clocksource: timekeeping watchdog on CPU13: wd-tsc-wd read-back delay 1000614ns, attempt 3, marking unstable

Therefore, add some context so that the message appears as follows:

clocksource: timekeeping watchdog on CPU13: wd-tsc-wd excessive read-back delay of 1000614ns vs. limit of 125000ns, wd-wd read-back delay only 27ns, attempt 3, marking tsc unstable

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Cc: John Stultz <jstultz@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Stephen Boyd <sboyd@kernel.org>
Cc: Feng Tang <feng.tang@intel.com>
---
kernel/time/clocksource.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/time/clocksource.c b/kernel/time/clocksource.c
index a3d19f6660ac7..b59914953809f 100644
--- a/kernel/time/clocksource.c
+++ b/kernel/time/clocksource.c
@@ -260,8 +260,8 @@ static enum wd_read_status cs_watchdog_read(struct clocksource *cs, u64 *csnow,
goto skip_test;
}

- pr_warn("timekeeping watchdog on CPU%d: wd-%s-wd read-back delay of %lldns, attempt %d, marking unstable\n",
- smp_processor_id(), cs->name, wd_delay, nretries);
+ pr_warn("timekeeping watchdog on CPU%d: wd-%s-wd excessive read-back delay of %lldns vs. limit of %ldns, wd-wd read-back delay only %lldns, attempt %d, marking %s unstable\n",
+ smp_processor_id(), cs->name, wd_delay, WATCHDOG_MAX_SKEW, wd_seq_delay, nretries, cs->name);
return WD_READ_UNSTABLE;

skip_test:
--
2.31.1.189.g2e36527f23