John Stultz dc491596f6 timekeeping: Rework frequency adjustments to work better w/ nohz ... The existing timekeeping_adjust logic has always been complicated to understand. Further, since it was developed prior to NOHZ becoming common, its not surprising it performs poorly when NOHZ is enabled. Since Miroslav pointed out the problematic nature of the existing code in the NOHZ case, I've tried to refactor the code to perform better. The problem with the previous approach was that it tried to adjust for the total cumulative error using a scaled dampening factor. This resulted in large errors to be corrected slowly, while small errors were corrected quickly. With NOHZ the timekeeping code doesn't know how far out the next tick will be, so this results in bad over-correction to small errors, and insufficient correction to large errors. Inspired by Miroslav's patch, I've refactored the code to try to address the correction in two steps. 1) Check the future freq error for the next tick, and if the frequency error is large, try to make sure we correct it so it doesn't cause much accumulated error. 2) Then make a small single unit adjustment to correct any cumulative error that has collected over time. This method performs fairly well in the simulator Miroslav created. Major credit to Miroslav for pointing out the issue, providing the original patch to resolve this, a simulator for testing, as well as helping debug and resolve issues in my implementation so that it performed closer to his original implementation. Cc: Miroslav Lichvar <mlichvar@redhat.com> Cc: Richard Cochran <richardcochran@gmail.com> Cc: Prarit Bhargava <prarit@redhat.com> Reported-by: Miroslav Lichvar <mlichvar@redhat.com> Signed-off-by: John Stultz <john.stultz@linaro.org>		2014-07-23 15:01:56 -07:00
..
debug	kdb: Use ktime_get_ts()	2014-06-12 16:18:45 +02:00
events	Oleg Nesterov found and fixed a bug in the perf/ftrace/uprobes code where	2014-07-03 18:37:25 -07:00
gcov	gcov: add support for GCC 4.9	2014-06-10 15:34:46 -07:00
irq	genirq: Fix memory leak when calling irq_free_hwirqs()	2014-07-05 21:42:08 +02:00
locking	Merge branch 'locking-urgent-for-linus.patch' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip	2014-06-21 07:06:02 -10:00
power	x86, kaslr: boot-time selectable with hibernation	2014-06-16 23:30:44 +02:00
printk	kernel/printk/printk.c: revert "printk: enable interrupts before calling console_trylock_for_printk()"	2014-07-03 09:21:54 -07:00
rcu	Merge branch 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip into next	2014-06-03 12:57:53 -07:00
sched	Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip	2014-06-12 19:42:15 -07:00
time	timekeeping: Rework frequency adjustments to work better w/ nohz	2014-07-23 15:01:56 -07:00
trace	ftrace: Provide trace clocks monotonic	2014-07-23 15:01:55 -07:00
.gitignore	Ignore generated file kernel/x509_certificate_list	2013-12-10 18:21:34 +00:00
acct.c	sched: Make task->start_time nanoseconds based	2014-07-23 10:18:05 -07:00
async.c
audit_tree.c	inotify: Fix reporting of cookies for inotify events	2014-02-18 11:17:17 +01:00
audit_watch.c	inotify: Fix reporting of cookies for inotify events	2014-02-18 11:17:17 +01:00
audit.c	Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next	2014-06-12 14:27:40 -07:00
audit.h	audit: Use struct net not pid_t to remember the network namespce to reply in	2014-03-20 10:10:53 -04:00
auditfilter.c	Merge git://git.infradead.org/users/eparis/audit	2014-04-12 12:38:53 -07:00
auditsc.c	auditsc: audit_krule mask accesses need bounds checking	2014-06-10 08:44:40 -07:00
backtracetest.c	kernel/backtracetest.c: replace no level printk by pr_info()	2014-06-04 16:54:14 -07:00
bounds.c	mm: do not allocate page->ptl dynamically, if spinlock_t fits to long	2013-12-20 12:25:45 -08:00
capability.c	fs,userns: Change inode_capable to capable_wrt_inode_uidgid	2014-06-10 13:57:22 -07:00
cgroup_freezer.c	cgroup: remove css_parent()	2014-05-16 13:22:48 -04:00
cgroup.c	cgroup: fix a race between cgroup_mount() and cgroup_kill_sb()	2014-06-30 10:16:26 -04:00
compat.c	kernel/compat.c: use sizeof() instead of sizeof	2014-06-04 16:54:19 -07:00
configs.c
context_tracking.c	x86/kprobes: Fix build errors and blacklist context_track_user	2014-06-14 09:07:44 +02:00
cpu_pm.c
cpu.c	More ACPI and power management updates for 3.16-rc1	2014-06-12 13:14:19 -07:00
cpuset.c	cpuset: break kernfs active protection in cpuset_write_resmask()	2014-07-01 16:42:28 -04:00
crash_dump.c
cred.c
delayacct.c	delayacct: Remove braindamaged type conversions	2014-07-23 10:18:06 -07:00
dma.c
elfcore.c
exec_domain.c	kernel/exec_domain.c: code clean-up	2014-06-04 16:54:15 -07:00
exit.c	signals: mv {dis,}allow_signal() from sched.h/exit.c to signal.[ch]	2014-06-06 16:08:11 -07:00
extable.c	asmlinkage: Make main_extable_sort_needed visible	2014-02-13 18:13:22 -08:00
fork.c	sched: Make task->start_time nanoseconds based	2014-07-23 10:18:05 -07:00
freezer.c	libata, freezer: avoid block device removal while system is frozen	2013-12-19 13:50:32 -05:00
futex_compat.c	compat: Get rid of (get|put)_compat_time(val|spec)	2014-02-02 14:09:12 -08:00
futex.c	Merge branch 'next' (accumulated 3.16 merge window patches) into master	2014-06-08 11:31:16 -07:00
groups.c	kernel/groups.c: remove return value of set_groups	2014-04-03 16:21:05 -07:00
hung_task.c	kernel/hung_task.c: convert simple_strtoul to kstrtouint	2014-06-04 16:54:15 -07:00
irq_work.c	perf/x86: Warn to early_printk() in case irq_work is too slow	2014-02-21 21:49:07 +01:00
jump_label.c
kallsyms.c	kernel: use macros from compiler.h instead of __attribute__((...))	2014-04-07 16:36:11 -07:00
kcmp.c
Kconfig.freezer
Kconfig.hz	kernel: remove CONFIG_USE_GENERIC_SMP_HELPERS	2013-11-15 09:32:22 +09:00
Kconfig.locks	locking/rwlocks: Introduce 'qrwlocks' - fair, queued rwlocks	2014-06-06 07:58:28 +02:00
Kconfig.preempt
kexec.c	kexec: save PG_head_mask in VMCOREINFO	2014-06-23 16:47:43 -07:00
kmod.c	signals: change wait_for_helper() to use kernel_sigaction()	2014-06-06 16:08:12 -07:00
kprobes.c	kprobes: Show blacklist entries via debugfs	2014-04-24 10:26:41 +02:00
ksysfs.c	kobject: Make support for uevent_helper optional.	2014-04-25 12:00:49 -07:00
kthread.c	kthread: fix return value of kthread_create() upon SIGKILL.	2014-06-04 16:53:51 -07:00
latencytop.c	kernel/latencytop.c: convert seq_printf to seq_puts	2014-06-04 16:54:15 -07:00
Makefile	time/timers: Move all time(r) related files into kernel/time	2014-06-23 11:22:35 +02:00
module_signing.c
module-internal.h
module.c	Most of this is cleaning up various driver sysfs permissions so we can	2014-06-11 16:09:14 -07:00
notifier.c	kprobes, notifier: Use NOKPROBE_SYMBOL macro in notifier	2014-04-24 10:26:39 +02:00
nsproxy.c
padata.c	padata: Fix wrong usage of rcu_dereference()	2013-12-05 21:28:42 +08:00
panic.c	kernel/panic.c: add "crash_kexec_post_notifiers" option for kdump after panic_notifers	2014-06-06 16:08:12 -07:00
params.c	param: hand arguments after -- straight to init	2014-04-28 11:48:34 +09:30
pid_namespace.c	pid_namespace: pidns_get() should check task_active_pid_ns() != NULL	2014-04-02 16:20:21 -07:00
pid.c
profile.c	kernel/profile.c: use static const char instead of static char	2014-06-06 16:08:13 -07:00
ptrace.c	kernel/compat: convert to COMPAT_SYSCALL_DEFINE	2014-03-06 15:35:10 +01:00
range.c
reboot.c	kernel/reboot.c: convert simple_strtoul to kstrtoint	2014-06-04 16:54:15 -07:00
relay.c	Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs	2014-04-12 14:49:50 -07:00
res_counter.c	kernel/res_counter.c: replace simple_strtoull by kstrtoull	2014-06-04 16:54:15 -07:00
resource.c	resources: Clarify sanity check message	2014-05-23 10:47:21 -06:00
seccomp.c	Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next	2014-06-12 14:27:40 -07:00
signal.c	signals: introduce kernel_sigaction()	2014-06-06 16:08:12 -07:00
smp.c	CPU hotplug, smp: flush any pending IPI callbacks before CPU offline	2014-06-23 16:47:43 -07:00
smpboot.c
smpboot.h
softirq.c	Merge branch 'rcu/next' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu into core/rcu	2014-05-22 11:36:10 +02:00
stacktrace.c
stop_machine.c	kernel/stop_machine.c: kernel-doc warning fix	2014-06-04 16:54:15 -07:00
sys_ni.c	sys_sgetmask/sys_ssetmask: add CONFIG_SGETMASK_SYSCALL	2014-06-04 16:54:14 -07:00
sys.c	sched: Consolidate open coded implementations of nice level frobbing into nice_to_rlimit() and rlimit_to_nice()	2014-05-22 11:16:36 +02:00
sysctl_binary.c	kernel/sysctl_binary.c: use scnprintf() instead of snprintf()	2013-11-13 12:09:33 +09:00
sysctl.c	kernel/watchdog.c: print traces for all cpus on lockup detection	2014-06-23 16:47:44 -07:00
system_certificates.S	KEYS: correct alignment of system_certificate_list content in assembly file	2013-12-10 18:25:28 +00:00
system_keyring.c	KEYS: correct alignment of system_certificate_list content in assembly file	2013-12-10 18:25:28 +00:00
task_work.c
taskstats.c	genetlink: only pass array to genl_register_family_with_ops()	2013-11-19 16:39:05 -05:00
test_kprobes.c
torture.c	torture: Remove __init from torture_init_begin/end	2014-05-14 09:46:30 -07:00
tracepoint.c	tracing: syscall_regfunc() should not skip kernel threads	2014-06-21 00:15:26 -04:00
tsacct.c	sched: Make task->start_time nanoseconds based	2014-07-23 10:18:05 -07:00
uid16.c
up.c	smp: Rename __smp_call_function_single() to smp_call_function_single_async()	2014-02-24 14:47:15 -08:00
user_namespace.c	kernel/user_namespace.c: kernel-doc/checkpatch fixes	2014-06-06 16:08:13 -07:00
user-return-notifier.c
user.c	kernel/user.c: drop unused field 'files' from user_struct	2014-06-04 16:54:16 -07:00
utsname_sysctl.c	sysctl: convert use of typedef ctl_table to struct ctl_table	2014-06-06 16:08:16 -07:00
utsname.c
watchdog.c	kernel/watchdog.c: print traces for all cpus on lockup detection	2014-06-23 16:47:44 -07:00
workqueue_internal.h	workqueue: rename manager_mutex to attach_mutex	2014-05-20 10:59:32 -04:00
workqueue.c	workqueue: zero cpumask of wq_numa_possible_cpumask on init	2014-07-07 09:56:48 -04:00