Kasper Pedersen a6d553ac64 time: Compensate for rounding on odd-frequency clocksources ...

commit a386b5af8e upstream.

When the clocksource is not a multiple of HZ, the clock will be off.  For
acpi_pm, HZ=1000 the error is 127.111 ppm:

The rounding of cycle_interval ends up generating a false error term in
ntp_error accumulation since xtime_interval is not exactly 1/HZ.  So, we
subtract out the error caused by the rounding.

This has been visible since 2.6.32-rc2
	commit a092ff0f90
	time: Implement logarithmic time accumulation
That commit raised NTP_INTERVAL_FREQ and exposed the rounding error.

testing tool: http://n1.taur.dk/permanent/testpmt.c
Also tested with ntpd and a frequency counter.

Signed-off-by: Kasper Pedersen <kkp2010@kasperkp.dk>
Acked-by: john stultz <johnstul@us.ibm.com>
Cc: John Kacur <jkacur@redhat.com>
Cc: Clark Williams <williams@redhat.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Will Tisdale <willtisdale@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

2011-06-23 15:24:09 -07:00

..

gcov

gcov: fix null-pointer dereference for certain module types

2010-09-20 13:17:53 -07:00

irq

genirq: Add IRQF_FORCE_RESUME

2011-06-23 15:24:09 -07:00

power

PM / Hibernate: Return error code when alloc_image_page() fails

2011-03-02 09:46:50 -05:00

time

time: Compensate for rounding on odd-frequency clocksources

2011-06-23 15:24:09 -07:00

trace

ftrace: Only update the function code on write to filter files

2011-06-23 15:24:00 -07:00

.gitignore

…

acct.c

bsdacct: fix uid/gid misreporting

2009-12-18 14:03:52 -08:00

async.c

…

audit_tree.c

fix more leaks in audit_tree.c tag_chunk()

2010-01-18 10:19:50 -08:00

audit_watch.c

Audit: reorganize struct audit_watch to save 8 bytes

2009-09-24 03:50:25 -04:00

audit.c

Audit: send signal info if selinux is disabled

2009-09-24 03:50:26 -04:00

audit.h

…

auditfilter.c

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auditsc.c

Audit: rearrange audit_context to save 16 bytes per struct

2009-09-24 03:50:26 -04:00

backtracetest.c

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bounds.c

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capability.c

sched: Remove remaining USER_SCHED code

2011-02-17 15:37:19 -08:00

cgroup_freezer.c

Freezer: Fix buggy resume test for tasks frozen with cgroup freezer

2010-04-26 07:41:17 -07:00

cgroup.c

cgroups: fix 2.6.32 regression causing BUG_ON() in cgroup_diput()

2010-01-18 10:19:32 -08:00

compat.c

compat: Make compat_alloc_user_space() incorporate the access_ok()

2010-09-20 13:17:57 -07:00

configs.c

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cpu.c

sched: _cpu_down(): Don't play with current->cpus_allowed

2010-09-20 13:18:08 -07:00

cpuset.c

cpuset: add a missing unlock in cpuset_write_resmask()

2011-03-14 14:29:52 -07:00

cred.c

CRED: Fix memory and refcount leaks upon security_prepare_creds() failure

2011-03-02 09:46:39 -05:00

delayacct.c

headers: taskstats_kern.h trim

2009-09-18 09:48:52 -07:00

dma.c

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exec_domain.c

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exit.c

sched: Remove remaining USER_SCHED code

2011-02-17 15:37:19 -08:00

extable.c

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fork.c

sched: Fix fork vs hotplug vs cpuset namespaces

2010-09-20 13:18:02 -07:00

freezer.c

…

futex_compat.c

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futex.c

futex: Fix errors in nested key ref-counting

2010-11-22 10:47:31 -08:00

groups.c

kernel/groups.c: fix integer overflow in groups_search

2010-09-20 13:17:54 -07:00

hrtimer.c

hrtimer: Preserve timer state in remove_hrtimer()

2010-10-28 21:44:01 -07:00

hung_task.c

sysctl: remove "struct file *" argument of ->proc_handler

2009-09-24 07:21:04 -07:00

itimer.c

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kallsyms.c

kallsyms: use new arch_is_kernel_text()

2009-09-23 07:39:30 -07:00

Kconfig.freezer

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Kconfig.hz

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Kconfig.preempt

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kexec.c

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kfifo.c

kfifo: Use "const" definitions

2009-09-19 13:13:17 -07:00

kgdb.c

repair gdbstub to match the gdbserial protocol specification

2011-04-14 16:53:40 -07:00

kmod.c

Revert "kmod: fix race in usermodehelper code"

2009-09-23 18:12:10 -07:00

kprobes.c

const: constify remaining file_operations

2009-10-01 16:11:11 -07:00

ksysfs.c

sched: Remove USER_SCHED

2011-02-17 15:37:19 -08:00

kthread.c

cpuset: fix the problem that cpuset_mem_spread_node() returns an offline node

2010-04-01 15:58:46 -07:00

latencytop.c

latencytop: fix per task accumulator

2010-12-09 13:26:51 -08:00

lockdep_internals.h

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lockdep_proc.c

seq_file: constify seq_operations

2009-09-23 07:39:29 -07:00

lockdep_states.h

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lockdep.c

lockdep: Fix lock_is_held() on recursion

2011-06-23 15:24:06 -07:00

Makefile

SLOW_WORK: Move slow_work's proc file to debugfs

2009-12-01 08:20:31 -08:00

module.c

dynamic debug: move ddebug_remove_module() down into free_module()

2010-08-02 10:20:47 -07:00

mutex-debug.c

headers: remove sched.h from interrupt.h

2009-10-11 11:20:58 -07:00

mutex-debug.h

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mutex.c

mutex: Fix optimistic spinning vs. BKL

2010-07-05 11:10:31 -07:00

mutex.h

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notifier.c

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ns_cgroup.c

cgroups: let ss->can_attach and ss->attach do whole threadgroups at a time

2009-09-24 07:20:58 -07:00

nsproxy.c

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panic.c

Merge branch 'core-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

2009-10-08 12:16:35 -07:00

params.c

param: fix setting arrays of bool

2009-10-29 08:56:20 +10:30

perf_event.c

perf: Better fit max unprivileged mlock pages for tools needs

2011-04-14 16:53:17 -07:00

pid_namespace.c

pidns: deny CLONE_PARENT|CLONE_NEWPID combination

2009-09-24 07:21:04 -07:00

pid.c

next_pidmap: fix overflow condition

2011-04-22 08:44:25 -07:00

pm_qos_params.c

…

posix-cpu-timers.c

…

posix-timers.c

posix_timer: Fix error path in timer_create

2010-07-05 11:10:30 -07:00

printk.c

nohz: Fix printk_needs_cpu() return value on offline cpus

2011-01-07 14:43:03 -08:00

profile.c

profile: fix stats and data leakage

2010-05-26 14:29:18 -07:00

ptrace.c

ptrace: use safer wake up on ptrace_detach()

2011-02-17 15:37:03 -08:00

rcupdate.c

rcu: Move rcu_barrier() to rcutree

2009-10-07 08:11:20 +02:00

rcutorture.c

rcu: Clean up code to address Ingo's checkpatch feedback

2009-09-23 19:46:30 +02:00

rcutree_plugin.h

rcu: Remove inline from forward-referenced functions

2009-12-18 14:03:04 -08:00

rcutree_trace.c

rcu: Make hot-unplugged CPU relinquish its own RCU callbacks

2009-10-07 08:11:20 +02:00

rcutree.c

rcu: Fix note_new_gpnum() uses of ->gpnum

2009-12-18 14:03:01 -08:00

rcutree.h

rcu: Remove inline from forward-referenced functions

2009-12-18 14:03:04 -08:00

relay.c

const: mark struct vm_struct_operations

2009-09-27 11:39:25 -07:00

res_counter.c

memcg: some modification to softlimit under hierarchical memory reclaim.

2009-10-01 16:11:13 -07:00

resource.c

walk system ram range

2009-09-23 07:39:41 -07:00

rtmutex_common.h

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rtmutex-debug.c

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rtmutex-debug.h

…

rtmutex-tester.c

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rtmutex.c

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rtmutex.h

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rwsem.c

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sched_clock.c

sched: Fix cpu_clock() in NMIs, on !CONFIG_HAVE_UNSTABLE_SCHED_CLOCK

2010-01-22 15:18:30 -08:00

sched_cpupri.c

…

sched_cpupri.h

…

sched_debug.c

sched: Remove remaining USER_SCHED code

2011-02-17 15:37:19 -08:00

sched_fair.c

sched: Fix wake_affine() vs RT tasks

2011-02-17 15:37:30 -08:00

sched_features.h

sched: Remove irq time from available CPU power

2011-02-17 15:37:27 -08:00

sched_idletask.c

sched: Fix TASK_WAKING vs fork deadlock

2010-09-20 13:18:09 -07:00

sched_rt.c

sched: Do not account irq time to current task

2011-02-17 15:37:26 -08:00

sched_stats.h

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sched.c

ftrace: Fix memory leak with function graph and cpu hotplug

2011-03-23 13:16:39 -07:00

seccomp.c

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semaphore.c

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signal.c

Relax si_code check in rt_sigqueueinfo and rt_tgsigqueueinfo

2011-04-14 16:53:24 -07:00

slow-work-debugfs.c

SLOW_WORK: Move slow_work's proc file to debugfs

2009-12-01 08:20:31 -08:00

slow-work.c

slow-work: use get_ref wrapper instead of directly calling get_ref

2010-08-10 10:20:45 -07:00

slow-work.h

SLOW_WORK: Move slow_work's proc file to debugfs

2009-12-01 08:20:31 -08:00

smp.c

smp_call_function_many: handle concurrent clearing of mask

2011-03-23 13:16:55 -07:00

softirq.c

sched: Call tick_check_idle before __irq_enter

2011-02-17 15:37:27 -08:00

softlockup.c

softlockup: Stop spurious softlockup messages due to overflow

2010-04-01 15:58:47 -07:00

spinlock.c

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srcu.c

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stacktrace.c

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stop_machine.c

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sys_ni.c

Merge branch 'master' of /home/davem/src/GIT/linux-2.6/

2009-09-24 15:13:11 -07:00

sys.c

sched: Remove USER_SCHED

2011-02-17 15:37:19 -08:00

sysctl_check.c

NET: fix oops at bootime in sysctl code

2010-02-09 04:51:02 -08:00

sysctl.c

kernel/sysctl.c: fix stable merge error in NOMMU mmap_min_addr

2010-01-18 10:19:49 -08:00

taskstats.c

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test_kprobes.c

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time.c

time: Prevent 32 bit overflow with set_normalized_timespec()

2009-09-15 10:17:30 +02:00

timeconst.pl

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timer.c

nohz: Fix get_next_timer_interrupt() vs cpu hotplug

2011-01-07 14:43:03 -08:00

tracepoint.c

trivial: fix typo "to to" in multiple files

2009-09-21 15:14:55 +02:00

tsacct.c

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uid16.c

headers: utsname.h redux

2009-09-23 18:13:10 -07:00

up.c

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user_namespace.c

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user.c

kernel/user.c: add lock release annotation on free_user()

2011-02-17 15:37:31 -08:00

utsname_sysctl.c

sysctl: remove "struct file *" argument of ->proc_handler

2009-09-24 07:21:04 -07:00

utsname.c

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wait.c

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workqueue.c

workqueue: fix race condition in schedule_on_each_cpu()

2009-11-17 17:40:33 -08:00