diff options
7 files changed, 49 insertions, 12 deletions
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 9725c546a0d4..3ea934b034f7 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -603,8 +603,8 @@ clocksource.max_cswd_read_retries= [KNL] Number of clocksource_watchdog() retries due to external delays before the clock will be marked - unstable. Defaults to three retries, that is, - four attempts to read the clock under test. + unstable. Defaults to two retries, that is, + three attempts to read the clock under test. clocksource.verify_n_cpus= [KNL] Limit the number of CPUs checked for clocksources diff --git a/kernel/time/clocksource.c b/kernel/time/clocksource.c index b8a14d2fb5ba..b7e52a642948 100644 --- a/kernel/time/clocksource.c +++ b/kernel/time/clocksource.c @@ -107,7 +107,7 @@ static u64 suspend_start; * This delay could be due to SMIs, NMIs, or to VCPU preemptions. Used as * a lower bound for cs->uncertainty_margin values when registering clocks. */ -#define WATCHDOG_MAX_SKEW (50 * NSEC_PER_USEC) +#define WATCHDOG_MAX_SKEW (100 * NSEC_PER_USEC) #ifdef CONFIG_CLOCKSOURCE_WATCHDOG static void clocksource_watchdog_work(struct work_struct *work); @@ -199,23 +199,30 @@ void clocksource_mark_unstable(struct clocksource *cs) spin_unlock_irqrestore(&watchdog_lock, flags); } -ulong max_cswd_read_retries = 3; +ulong max_cswd_read_retries = 2; module_param(max_cswd_read_retries, ulong, 0644); EXPORT_SYMBOL_GPL(max_cswd_read_retries); static int verify_n_cpus = 8; module_param(verify_n_cpus, int, 0644); -static bool cs_watchdog_read(struct clocksource *cs, u64 *csnow, u64 *wdnow) +enum wd_read_status { + WD_READ_SUCCESS, + WD_READ_UNSTABLE, + WD_READ_SKIP +}; + +static enum wd_read_status cs_watchdog_read(struct clocksource *cs, u64 *csnow, u64 *wdnow) { unsigned int nretries; - u64 wd_end, wd_delta; - int64_t wd_delay; + u64 wd_end, wd_end2, wd_delta; + int64_t wd_delay, wd_seq_delay; for (nretries = 0; nretries <= max_cswd_read_retries; nretries++) { local_irq_disable(); *wdnow = watchdog->read(watchdog); *csnow = cs->read(cs); wd_end = watchdog->read(watchdog); + wd_end2 = watchdog->read(watchdog); local_irq_enable(); wd_delta = clocksource_delta(wd_end, *wdnow, watchdog->mask); @@ -226,13 +233,34 @@ static bool cs_watchdog_read(struct clocksource *cs, u64 *csnow, u64 *wdnow) pr_warn("timekeeping watchdog on CPU%d: %s retried %d times before success\n", smp_processor_id(), watchdog->name, nretries); } - return true; + return WD_READ_SUCCESS; } + + /* + * Now compute delay in consecutive watchdog read to see if + * there is too much external interferences that cause + * significant delay in reading both clocksource and watchdog. + * + * If consecutive WD read-back delay > WATCHDOG_MAX_SKEW/2, + * report system busy, reinit the watchdog and skip the current + * watchdog test. + */ + wd_delta = clocksource_delta(wd_end2, wd_end, watchdog->mask); + wd_seq_delay = clocksource_cyc2ns(wd_delta, watchdog->mult, watchdog->shift); + if (wd_seq_delay > WATCHDOG_MAX_SKEW/2) + goto skip_test; } pr_warn("timekeeping watchdog on CPU%d: %s read-back delay of %lldns, attempt %d, marking unstable\n", smp_processor_id(), watchdog->name, wd_delay, nretries); - return false; + return WD_READ_UNSTABLE; + +skip_test: + pr_info("timekeeping watchdog on CPU%d: %s wd-wd read-back delay of %lldns\n", + smp_processor_id(), watchdog->name, wd_seq_delay); + pr_info("wd-%s-wd read-back delay of %lldns, clock-skew test skipped!\n", + cs->name, wd_delay); + return WD_READ_SKIP; } static u64 csnow_mid; @@ -356,6 +384,7 @@ static void clocksource_watchdog(struct timer_list *unused) int next_cpu, reset_pending; int64_t wd_nsec, cs_nsec; struct clocksource *cs; + enum wd_read_status read_ret; u32 md; spin_lock(&watchdog_lock); @@ -373,9 +402,12 @@ static void clocksource_watchdog(struct timer_list *unused) continue; } - if (!cs_watchdog_read(cs, &csnow, &wdnow)) { - /* Clock readout unreliable, so give it up. */ - __clocksource_unstable(cs); + read_ret = cs_watchdog_read(cs, &csnow, &wdnow); + + if (read_ret != WD_READ_SUCCESS) { + if (read_ret == WD_READ_UNSTABLE) + /* Clock readout unreliable, so give it up. */ + __clocksource_unstable(cs); continue; } diff --git a/tools/testing/selftests/rcutorture/configs/rcu/SRCU-T b/tools/testing/selftests/rcutorture/configs/rcu/SRCU-T index d6557c38dfe4..c70cf0405f24 100644 --- a/tools/testing/selftests/rcutorture/configs/rcu/SRCU-T +++ b/tools/testing/selftests/rcutorture/configs/rcu/SRCU-T @@ -2,6 +2,7 @@ CONFIG_SMP=n CONFIG_PREEMPT_NONE=y CONFIG_PREEMPT_VOLUNTARY=n CONFIG_PREEMPT=n +CONFIG_PREEMPT_DYNAMIC=n #CHECK#CONFIG_TINY_SRCU=y CONFIG_RCU_TRACE=n CONFIG_DEBUG_LOCK_ALLOC=y diff --git a/tools/testing/selftests/rcutorture/configs/rcu/SRCU-U b/tools/testing/selftests/rcutorture/configs/rcu/SRCU-U index 6bc24e99862f..bc9eeabaa1b1 100644 --- a/tools/testing/selftests/rcutorture/configs/rcu/SRCU-U +++ b/tools/testing/selftests/rcutorture/configs/rcu/SRCU-U @@ -2,6 +2,7 @@ CONFIG_SMP=n CONFIG_PREEMPT_NONE=y CONFIG_PREEMPT_VOLUNTARY=n CONFIG_PREEMPT=n +CONFIG_PREEMPT_DYNAMIC=n #CHECK#CONFIG_TINY_SRCU=y CONFIG_RCU_TRACE=n CONFIG_DEBUG_LOCK_ALLOC=n diff --git a/tools/testing/selftests/rcutorture/configs/rcu/TINY01 b/tools/testing/selftests/rcutorture/configs/rcu/TINY01 index 6db705e55487..0953c52fcfd7 100644 --- a/tools/testing/selftests/rcutorture/configs/rcu/TINY01 +++ b/tools/testing/selftests/rcutorture/configs/rcu/TINY01 @@ -2,6 +2,7 @@ CONFIG_SMP=n CONFIG_PREEMPT_NONE=y CONFIG_PREEMPT_VOLUNTARY=n CONFIG_PREEMPT=n +CONFIG_PREEMPT_DYNAMIC=n #CHECK#CONFIG_TINY_RCU=y CONFIG_HZ_PERIODIC=n CONFIG_NO_HZ_IDLE=y diff --git a/tools/testing/selftests/rcutorture/configs/rcu/TINY02 b/tools/testing/selftests/rcutorture/configs/rcu/TINY02 index d8674264318d..30439f6fc20e 100644 --- a/tools/testing/selftests/rcutorture/configs/rcu/TINY02 +++ b/tools/testing/selftests/rcutorture/configs/rcu/TINY02 @@ -2,6 +2,7 @@ CONFIG_SMP=n CONFIG_PREEMPT_NONE=y CONFIG_PREEMPT_VOLUNTARY=n CONFIG_PREEMPT=n +CONFIG_PREEMPT_DYNAMIC=n #CHECK#CONFIG_TINY_RCU=y CONFIG_HZ_PERIODIC=y CONFIG_NO_HZ_IDLE=n diff --git a/tools/testing/selftests/rcutorture/configs/rcuscale/TINY b/tools/testing/selftests/rcutorture/configs/rcuscale/TINY index fb05ef5279b4..64e9490c1f79 100644 --- a/tools/testing/selftests/rcutorture/configs/rcuscale/TINY +++ b/tools/testing/selftests/rcutorture/configs/rcuscale/TINY @@ -2,6 +2,7 @@ CONFIG_SMP=n CONFIG_PREEMPT_NONE=y CONFIG_PREEMPT_VOLUNTARY=n CONFIG_PREEMPT=n +CONFIG_PREEMPT_DYNAMIC=n #CHECK#CONFIG_TINY_RCU=y CONFIG_HZ_PERIODIC=n CONFIG_NO_HZ_IDLE=y |