John Stultz
ec02b076ce
timekeeping: Cap adjustments so they don't exceed the maxadj value
...
Thus its been occasionally noted that users have seen
confusing warnings like:
Adjusting tsc more than 11% (5941981 vs 7759439)
We try to limit the maximum total adjustment to 11% (10% tick
adjustment + 0.5% frequency adjustment). But this is done by
bounding the requested adjustment values, and the internal
steering that is done by tracking the error from what was
requested and what was applied, does not have any such limits.
This is usually not problematic, but in some cases has a risk
that an adjustment could cause the clocksource mult value to
overflow, so its an indication things are outside of what is
expected.
It ends up most of the reports of this 11% warning are on systems
using chrony, which utilizes the adjtimex() ADJ_TICK interface
(which allows a +-10% adjustment). The original rational for
ADJ_TICK unclear to me but my assumption it was originally added
to allow broken systems to get a big constant correction at boot
(see adjtimex userspace package for an example) which would allow
the system to work w/ ntpd's 0.5% adjustment limit.
Chrony uses ADJ_TICK to make very aggressive short term corrections
(usually right at startup). Which push us close enough to the max
bound that a few late ticks can cause the internal steering to push
past the max adjust value (tripping the warning).
Thus this patch adds some extra logic to enforce the max adjustment
cap in the internal steering.
Note: This has the potential to slow corrections when the ADJ_TICK
value is furthest away from the default value. So it would be good to
get some testing from folks using chrony, to make sure we don't
cause any troubles there.
Cc: Miroslav Lichvar <mlichvar@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Andy Lutomirski <luto@kernel.org>
Tested-by: Miroslav Lichvar <mlichvar@redhat.com>
Reported-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: John Stultz <john.stultz@linaro.org>
2015-12-16 16:50:57 -08:00
..
bpf
bpf, verifier: annotate verbose printer with __printf
2015-11-03 11:29:56 -05:00
configs
kconfig: add xenconfig defconfig helper
2015-06-16 11:04:29 +01:00
debug
events
Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
2015-11-15 09:36:24 -08:00
gcov
gcov: add support for GCC 5.1
2015-06-30 19:44:57 -07:00
irq
Merge branches 'irq-urgent-for-linus' and 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
2015-11-15 09:30:48 -08:00
livepatch
livepatch: Improve error handling in klp_disable_func()
2015-07-14 22:48:06 +02:00
locking
mm, page_alloc: distinguish between being unable to sleep, unwilling to sleep and avoiding waking kswapd
2015-11-06 17:50:42 -08:00
power
mm, page_alloc: rename __GFP_WAIT to __GFP_RECLAIM
2015-11-06 17:50:42 -08:00
printk
printk: prevent userland from spoofing kernel messages
2015-11-06 17:50:42 -08:00
rcu
Merge branches 'doc.2015.10.06a', 'percpu-rwsem.2015.10.06a' and 'torture.2015.10.06a' into HEAD
2015-10-07 16:06:25 -07:00
sched
Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
2015-11-15 09:35:33 -08:00
time
timekeeping: Cap adjustments so they don't exceed the maxadj value
2015-12-16 16:50:57 -08:00
trace
This contains three more clean up patches.
2015-11-12 16:22:54 -08:00
.gitignore
certs: add .gitignore to stop git nagging about x509_certificate_list
2015-10-21 15:18:35 +01:00
acct.c
async.c
audit.c
mm, page_alloc: distinguish between being unable to sleep, unwilling to sleep and avoiding waking kswapd
2015-11-06 17:50:42 -08:00
audit.h
audit: audit_tree_match can be boolean
2015-11-04 08:23:51 -05:00
audit_fsnotify.c
audit: clean simple fsnotify implementation
2015-08-06 16:14:53 -04:00
audit_tree.c
audit: audit_tree_match can be boolean
2015-11-04 08:23:51 -05:00
audit_watch.c
Merge branch 'upstream' of git://git.infradead.org/users/pcmoore/audit
2015-09-08 13:34:59 -07:00
auditfilter.c
audit: fix comment block whitespace
2015-11-04 08:23:51 -05:00
auditsc.c
Merge branch 'upstream' of git://git.infradead.org/users/pcmoore/audit
2015-09-08 13:34:59 -07:00
backtracetest.c
bounds.c
capability.c
cgroup.c
mm, page_alloc: distinguish between being unable to sleep, unwilling to sleep and avoiding waking kswapd
2015-11-06 17:50:42 -08:00
cgroup_freezer.c
cgroup: allow a cgroup subsystem to reject a fork
2015-07-14 17:29:23 -04:00
cgroup_pids.c
cgroup: add cgroup_subsys->free() method and use it to fix pids controller
2015-10-15 16:41:53 -04:00
compat.c
configs.c
context_tracking.c
context_tracking: avoid irq_save/irq_restore on guest entry and exit
2015-11-10 12:06:23 +01:00
cpu.c
Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
2015-11-03 18:03:50 -08:00
cpu_pm.c
kernel/cpu_pm: fix cpu_cluster_pm_exit comment
2015-09-03 02:42:20 +02:00
cpuset.c
Merge branch 'akpm' (patches from Andrew)
2015-11-05 23:10:54 -08:00
crash_dump.c
cred.c
kernel/cred.c: remove unnecessary kdebug atomic reads
2015-09-10 13:29:01 -07:00
delayacct.c
dma.c
elfcore.c
exec_domain.c
exit.c
Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
2015-11-03 18:03:50 -08:00
extable.c
kernel/extable.c: remove duplicated include
2015-09-10 13:29:01 -07:00
fork.c
Merge branch 'akpm' (patches from Andrew)
2015-11-05 23:10:54 -08:00
freezer.c
futex.c
driver core update for 4.4-rc1
2015-11-04 21:50:37 -08:00
futex_compat.c
groups.c
hung_task.c
irq_work.c
jump_label.c
locking/static_keys: Add selftest
2015-08-03 11:34:16 +02:00
kallsyms.c
kcmp.c
Kconfig.freezer
Kconfig.hz
Kconfig.locks
Kconfig.preempt
kexec.c
kexec: use file name as the output message prefix
2015-11-06 17:50:42 -08:00
kexec_core.c
kexec: use file name as the output message prefix
2015-11-06 17:50:42 -08:00
kexec_file.c
kexec: use file name as the output message prefix
2015-11-06 17:50:42 -08:00
kexec_internal.h
kexec: split kexec_file syscall code to kexec_file.c
2015-09-10 13:29:01 -07:00
kmod.c
kmod: don't run async usermode helper as a child of kworker thread
2015-10-23 17:55:10 +09:00
kprobes.c
perf/x86/hw_breakpoints: Disallow kernel breakpoints unless kprobe-safe
2015-08-04 10:16:54 +02:00
ksysfs.c
kexec: split kexec_load syscall from kexec core code
2015-09-10 13:29:01 -07:00
kthread.c
kernel/kthread.c:kthread_create_on_node(): clarify documentation
2015-09-04 16:54:41 -07:00
latencytop.c
Makefile
sys_membarrier(): system-wide memory barrier (generic, x86)
2015-09-11 15:21:34 -07:00
membarrier.c
sys_membarrier(): system-wide memory barrier (generic, x86)
2015-09-11 15:21:34 -07:00
memremap.c
libnvdimm for 4.4:
2015-11-10 12:07:22 -08:00
module-internal.h
module.c
module: Fix locking in symbol_put_addr()
2015-08-24 10:37:01 +09:30
module_signing.c
KEYS: Merge the type-specific data with the payload data
2015-10-21 15:18:36 +01:00
notifier.c
Merge branch 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
2015-09-01 08:40:25 -07:00
nsproxy.c
padata.c
panic.c
panic: release stale console lock to always get the logbuf printed out
2015-11-06 17:50:42 -08:00
params.c
Nothing exciting, minor tweaks and cleanups.
2015-11-09 15:53:39 -08:00
pid.c
rcu: Rename rcu_lockdep_assert() to RCU_LOCKDEP_WARN()
2015-07-22 15:27:32 -07:00
pid_namespace.c
profile.c
mm: rename alloc_pages_exact_node() to __alloc_pages_node()
2015-09-08 15:35:28 -07:00
ptrace.c
seccomp, ptrace: add support for dumping seccomp filters
2015-10-27 19:55:13 -07:00
range.c
reboot.c
kexec: split kexec_load syscall from kexec core code
2015-09-10 13:29:01 -07:00
relay.c
kernel/relay.c: use kvfree() in relay_free_page_array()
2015-06-30 19:44:59 -07:00
resource.c
mm: enhance region_is_ram() to region_intersects()
2015-08-10 23:07:05 -04:00
seccomp.c
seccomp, ptrace: add support for dumping seccomp filters
2015-10-27 19:55:13 -07:00
signal.c
coredump: ensure all coredumping tasks have SIGNAL_GROUP_COREDUMP
2015-11-06 17:50:42 -08:00
smp.c
mm, page_alloc: distinguish between being unable to sleep, unwilling to sleep and avoiding waking kswapd
2015-11-06 17:50:42 -08:00
smpboot.c
stop_machine: Kill smp_hotplug_thread->pre_unpark, introduce stop_machine_unpark()
2015-10-20 10:23:55 +02:00
smpboot.h
softirq.c
stacktrace.c
stop_machine.c
sched: Move cpu_active() tests from stop_two_cpus() into migrate_swap_stop()
2015-10-20 10:25:56 +02:00
sys.c
pidns: fix set/getpriority and ioprio_set/get in PRIO_USER mode
2015-11-06 17:50:42 -08:00
sys_ni.c
mm: mlock: add new mlock system call
2015-11-05 19:34:48 -08:00
sysctl.c
kernel/watchdog.c: add sysctl knob hardlockup_panic
2015-11-05 19:34:48 -08:00
sysctl_binary.c
task_work.c
task_work: remove fifo ordering guarantee
2015-09-05 13:46:58 -07:00
taskstats.c
test_kprobes.c
torture.c
torture: Consolidate cond_resched_rcu_qs() into stutter_wait()
2015-10-06 11:25:01 -07:00
tracepoint.c
tracepoint: Give priority to probes of tracepoints
2015-10-25 21:33:54 -04:00
tsacct.c
uid16.c
up.c
user-return-notifier.c
user.c
user_namespace.c
capabilities: ambient capabilities
2015-09-04 16:54:41 -07:00
utsname.c
utsname_sysctl.c
watchdog.c
kernel/watchdog.c: fix race between proc_watchdog_thresh() and watchdog_timer_fn()
2015-11-05 19:34:48 -08:00
workqueue.c
Merge branch 'for-4.4' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq
2015-11-05 14:16:27 -08:00
workqueue_internal.h