Commit Graph

52 Commits

Author SHA1 Message Date
John Stultz
6b43ae8a61 ntp: Fix leap-second hrtimer livelock
Since commit 7dffa3c673 the ntp
subsystem has used an hrtimer for triggering the leapsecond
adjustment. However, this can cause a potential livelock.

Thomas diagnosed this as the following pattern:
CPU 0                                                    CPU 1
do_adjtimex()
  spin_lock_irq(&ntp_lock);
    process_adjtimex_modes();				 timer_interrupt()
      process_adj_status();                                do_timer()
        ntp_start_leap_timer();                             write_lock(&xtime_lock);
          hrtimer_start();                                  update_wall_time();
             hrtimer_reprogram();                            ntp_tick_length()
               tick_program_event()                            spin_lock(&ntp_lock);
                 clockevents_program_event()
		   ktime_get()
                     seq = req_seqbegin(xtime_lock);

This patch tries to avoid the problem by reverting back to not using
an hrtimer to inject leapseconds, and instead we handle the leapsecond
processing in the second_overflow() function.

The downside to this change is that on systems that support highres
timers, the leap second processing will occur on a HZ tick boundary,
(ie: ~1-10ms, depending on HZ)  after the leap second instead of
possibly sooner (~34us in my tests w/ x86_64 lapic).

This patch applies on top of tip/timers/core.

CC: Sasha Levin <levinsasha928@gmail.com>
CC: Thomas Gleixner <tglx@linutronix.de>
Reported-by: Sasha Levin <levinsasha928@gmail.com>
Diagnoised-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Sasha Levin <levinsasha928@gmail.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
2012-03-22 19:43:43 -07:00
John Stultz
ea7cf49a76 ntp: Access tick_length variable via ntp_tick_length()
Currently the NTP managed tick_length value is accessed globally,
in preparations for locking cleanups, make sure it is accessed via
a function and mark it as static.

CC: Thomas Gleixner <tglx@linutronix.de>
CC: Eric Dumazet <eric.dumazet@gmail.com>
CC: Richard Cochran <richardcochran@gmail.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
2012-01-26 19:44:23 -08:00
John Stultz
8357929e6a ntp: Cleanup timex.h
Move ntp_sycned to ntp.c and mark time_status as static.
Also yank function declaration for non-existant function.

CC: Thomas Gleixner <tglx@linutronix.de>
CC: Eric Dumazet <eric.dumazet@gmail.com>
CC: Richard Cochran <richardcochran@gmail.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
2012-01-26 19:44:20 -08:00
Richard Cochran
094aa1881f ntp: Add ADJ_SETOFFSET mode bit
This patch adds a new mode bit into the timex structure. When set, the bit
instructs the kernel to add the given time value to the current time.

Signed-off-by: Richard Cochran <richard.cochran@omicron.at>
Acked-by: John Stultz <johnstul@us.ibm.com>
LKML-Reference: <20110201134320.688829863@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2011-02-02 15:28:18 +01:00
Alexander Gordeev
025b40abe7 ntp: add hardpps implementation
This commit adds hardpps() implementation based upon the original one from
the NTPv4 reference kernel code from David Mills.  However, it is highly
optimized towards very fast syncronization and maximum stickness to PPS
signal.  The typical error is less then a microsecond.

To make it sync faster I had to throw away exponential phase filter so
that the full phase offset is corrected immediately.  Then I also had to
throw away median phase filter because it gives a bigger error itself if
used without exponential filter.

Maybe we will find an appropriate filtering scheme in the future but it's
not necessary if the signal quality is ok.

Signed-off-by: Alexander Gordeev <lasaine@lvk.cs.msu.su>
Acked-by: John Stultz <johnstul@us.ibm.com>
Cc: Rodolfo Giometti <giometti@enneenne.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-01-13 08:03:20 -08:00
John Stultz
3d0205bd13 ntp: Remove tickadj
There are zero users of tickadj. So remove it.

Signed-off-by: John Stultz <johnstul@us.ibm.com>
LKML-Reference: <1268968769-19209-2-git-send-email-johnstul@us.ibm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2010-03-23 17:19:38 +01:00
John Stultz
e1292ba164 ntp: Make time_adjust static
Now that no arches are accessing time_adjust directly,
make it static.

Signed-off-by: John Stultz <johnstul@us.ibm.com>
LKML-Reference: <1268968769-19209-1-git-send-email-johnstul@us.ibm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2010-03-23 17:19:37 +01:00
john stultz
1f5b8f8a20 ntp: Make time_esterror and time_maxerror static
Make time_esterror and time_maxerror static as no one uses them
outside of ntp.c
    
Signed-off-by: John Stultz <johnstul@us.ibm.com>
Cc: richard@rsk.demon.co.uk
LKML-Reference: <1264719761.3437.47.camel@localhost.localdomain>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2010-01-29 10:15:19 +01:00
Linus Torvalds
2b876f95d0 Merge branches 'timers-for-linus-ntp' and 'irq-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'timers-for-linus-ntp' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  ntp: Provide compability defines (You say MOD_NANO, I say ADJ_NANO)

* 'irq-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  genirq: do not execute DEBUG_SHIRQ when irq setup failed
2009-12-08 19:30:19 -08:00
john stultz
a092ff0f90 time: Implement logarithmic time accumulation
Accumulating one tick at a time works well unless we're using NOHZ.
Then it can be an issue, since we may have to run through the loop
a few thousand times, which can increase timer interrupt caused
latency.

The current solution was to accumulate in half-second intervals
with NOHZ. This kept the number of loops down, however it did
slightly change how we make NTP adjustments. While not an issue
with NTPd users, as NTPd makes adjustments over a longer period of
time, other adjtimex() users have noticed the half-second
granularity with which we can apply frequency changes to the clock.

For instance, if a application tries to apply a 100ppm frequency
correction for 20ms to correct a 2us offset, with NOHZ they either
get no correction, or a 50us correction.

Now, there will always be some granularity error for applying
frequency corrections. However with users sensitive to this error
have seen a 50-500x increase with NOHZ compared to running without
NOHZ.

So I figured I'd try another approach then just simply increasing
the interval. My approach is to consume the time interval
logarithmically. This reduces the number of times through the loop
needed keeping latency down, while still preserving the original
granularity error for adjtimex() changes.

Further, this change allows us to remove the xtime_cache code
(patch to follow), as xtime is always within one tick of the
current time, instead of the half-second updates it saw before.

An earlier version of this patch has been shipping to x86 users in
the RedHat MRG releases for awhile without issue, but I've reworked
this version to be even more careful about avoiding possible
overflows if the shift value gets too large.

Signed-off-by: John Stultz <johnstul@us.ibm.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: John Kacur <jkacur@redhat.com>
Cc: Clark Williams <williams@redhat.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
LKML-Reference: <1254525473.7741.88.camel@localhost.localdomain>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-10-05 13:51:48 +02:00
john stultz
c95b4502ad ntp: Provide compability defines (You say MOD_NANO, I say ADJ_NANO)
MOD_NANO, ADJ_NANO, MOD_NANO, ADJ_NANO!
Lets call the whole thing off!
But oh! If we call the whole thing off,
Then we must part.
And oh! If we ever part,
Then that might break my heart^H^H^H^Hclock!
So, if you like MOD_NANO and I like ADJ_NANO,
I'll include MOD_NANO and give up ADJ_NANO (not really!).
For we know we need each other,
So we better call the calling off off.
Let's call the whole thing off!

The tumultuous NTP and Linux relationship has hit another snag: Ends
up NTPd still uses the "xntp 3.4 compatability names" and when the
STA_NANO value was added (along with ADJ_NANO), NTPd expected MOD_NANO
to be added and has apparently hit some build errors.

Report to ntp hackers:
https://lists.ntp.org/pipermail/hackers/2009-August/004455.html

Related Bugs:
https://support.ntp.org/bugs/show_bug.cgi?id=1219
https://bugzilla.redhat.com/show_bug.cgi?id=505566

So in an effort to make peace, here's a patch to help get things
building again. I also have updated the comment to make sure folks
don't think the MOD_* values are just legacy constants.

Of course, NTPd really uses the glibc-headers, so those will need to
be similarly updated before things are working again (the RH bug above
should probably cover that).

Thanks to Michael Tatarinov and Hal Murray for finding and reporting
the issue!

Signed-off-by: John Stultz <johnstul@us.ibm.com>
Cc: Miroslav Lichvar <mlichvar@redhat.com>
Cc: hmurray@megapathdsl.net
Cc: Ulrich Drepper <drepper@redhat.com>
Cc: Michael Tatarinov <kukabu@gmail.com>
LKML-Reference: <1251417882.7905.42.camel@localhost.localdomain>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2009-08-28 14:53:24 +02:00
Arnd Bergmann
08604bd993 time: move PIT_TICK_RATE to linux/timex.h
PIT_TICK_RATE is currently defined in four architectures, but in three
different places.  While linux/timex.h is not the perfect place for it, it
is still a reasonable replacement for those drivers that traditionally use
asm/timex.h to get CLOCK_TICK_RATE and expect it to be the PIT frequency.

Note that for Alpha, the actual value changed from 1193182UL to 1193180UL.
 This is unlikely to make a difference, and probably can only improve
accuracy.  There was a discussion on the correct value of CLOCK_TICK_RATE
a few years ago, after which every existing instance was getting changed
to 1193182.  According to the specification, it should be
1193181.818181...

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Len Brown <lenb@kernel.org>
Cc: john stultz <johnstul@us.ibm.com>
Cc: Dmitry Torokhov <dtor@mail.ru>
Cc: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-06-16 19:47:27 -07:00
john stultz
e13cf6e04e ntp: fix comment typos
Bernhard Schiffner noticed I had a few comment typos in this patch,
(note: to save embarrassment, when making typos, avoid copying and
pasting them) so this patch corrects them.

[ Impact: cleanup ]

Reported-by: Bernhard Schiffner <bernhard@schiffner-limbach.de>
Signed-off-by: John Stultz <johnstul@us.ibm.com>
Cc: riel@redhat.com
Cc: akpm@linux-foundation.org
LKML-Reference: <1242090794.7214.131.camel@localhost.localdomain>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-05-12 10:35:15 +02:00
john stultz
22cfbbfd9f ntp: adjust SHIFT_PLL to improve NTP convergence
The conversion to the ntpv4 reference model
f199239373 ("ntp: convert to the NTP4
reference model") in 2.6.19 added nanosecond resolution the adjtimex
interface, but also changed the "stiffness" of the frequency adjustments,
causing NTP convergence time to greatly increase.

SHIFT_PLL, which reduces the stiffness of the freq adjustments, was
designed to be inversely linked to HZ, and the reference value of 4 was
designed for Unix systems using HZ=100.  However Linux's clock steering
code mostly independent of HZ.

So this patch reduces the SHIFT_PLL value from 4 to 2, which causes NTPd
behavior to match kernels prior to 2.6.19, greatly reducing convergence
times, and improving close synchronization through environmental thermal
changes.

The patch also changes some l's to L's in nearby code to avoid misreading
50l as 501.

[ Impact: tweak NTP algorithm for faster convergence ]

Signed-off-by: John Stultz <johnstul@us.ibm.com>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: zippel@linux-m68k.org
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
LKML-Reference: <200905051956.n45JuVo9025575@imap1.linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-05-06 11:44:02 +02:00
Ingo Molnar
2b9d1496e7 time: ntp: make 64-bit constants more robust
Impact: cleanup, no functionality changed

 - make PPM_SCALE an explicit s64 constant, to
   remove (s64) casts from usage sites.

kernel/time/ntp.o:

   text	   data	    bss	    dec	    hex	filename
   2536	    114	    136	   2786	    ae2	ntp.o.before
   2536	    114	    136	   2786	    ae2	ntp.o.after

md5:
   40a7728d1188aa18e83e21a81fa7b150  ntp.o.before.asm
   40a7728d1188aa18e83e21a81fa7b150  ntp.o.after.asm

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-02-25 18:38:15 +01:00
Mike Frysinger
c29541b24f linux/timex.h: cleanup for userspace
Impact: fix user-space exported use

Move all the kernel-specific defines and includes into the __KERNEL__
section so that they don't get leaked into userspace.

[akpm@linux-foundation.org: coding-style fixes]

Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-12-12 17:01:38 +01:00
Roman Zippel
d40e944c25 ntp: improve adjtimex frequency rounding
Change PPM_SCALE_INV_SHIFT so that it doesn't throw away any input bits
(19 is the amount of the factor 2 in PPM_SCALE), the output frequency
can then be calculated back to its input value, as the inverse divide
produce a slightly larger value, which is then correctly rounded by the
final shift.

Reported-by: Martin Ziegler <ziegler@uni-freiburg.de>
Signed-off-by: Roman Zippel <zippel@linux-m68k.org>
Cc: John Stultz <johnstul@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-09-24 17:33:13 +02:00
Roman Zippel
916c7a8551 ntp: fix ADJ_OFFSET_SS_READ bug and do_adjtimex() cleanup
Thanks to the review by Michael Kerrisk a bug in the recent
ADJ_OFFSET_SS_READ option was discovered, where the ntp time_offset was
inadvertently set by it.  This fixes this by making the adjtime code
more separate from the ntp_adjtime code (both of which really want to
be separate syscalls).

Signed-off-by: Roman Zippel <zippel@linux-m68k.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: John Stultz <johnstul@us.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-08-22 06:40:18 +02:00
Roman Zippel
7dffa3c673 ntp: handle leap second via timer
Remove the leap second handling from second_overflow(), which doesn't have to
check for it every second anymore.  With CONFIG_NO_HZ this also makes sure the
leap second is handled close to the full second.  Additionally this makes it
possible to abort a leap second properly by resetting the STA_INS/STA_DEL
status bits.

Signed-off-by: Roman Zippel <zippel@linux-m68k.org>
Cc: john stultz <johnstul@us.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-05-01 08:03:59 -07:00
Roman Zippel
8383c42399 ntp: remove current_tick_length()
current_tick_length used to do a little more, but now it just returns
tick_length, which we can also access directly at the few places, where it's
needed.

Signed-off-by: Roman Zippel <zippel@linux-m68k.org>
Cc: john stultz <johnstul@us.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-05-01 08:03:59 -07:00
Roman Zippel
7fc5c78409 ntp: rename TICK_LENGTH_SHIFT to NTP_SCALE_SHIFT
As TICK_LENGTH_SHIFT is used for more than just the tick length, the name
isn't quite approriate anymore, so this renames it to NTP_SCALE_SHIFT.

Signed-off-by: Roman Zippel <zippel@linux-m68k.org>
Cc: john stultz <johnstul@us.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-05-01 08:03:59 -07:00
Roman Zippel
153b5d054a ntp: support for TAI
This adds support for setting the TAI value (International Atomic Time).  The
value is reported back to userspace via timex (as we don't have a
ntp_gettime() syscall).

Signed-off-by: Roman Zippel <zippel@linux-m68k.org>
Cc: john stultz <johnstul@us.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-05-01 08:03:59 -07:00
Roman Zippel
9f14f669d1 ntp: increase time_offset resolution
time_offset is already a 64bit value but its resolution barely used, so this
makes better use of it by replacing SHIFT_UPDATE with TICK_LENGTH_SHIFT.

Side note: the SHIFT_HZ in SHIFT_UPDATE was incorrect for CONFIG_NO_HZ and the
primary reason for changing time_offset to 64bit to avoid the overflow.

Signed-off-by: Roman Zippel <zippel@linux-m68k.org>
Cc: john stultz <johnstul@us.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-05-01 08:03:58 -07:00
Roman Zippel
074b3b8794 ntp: increase time_freq resolution
This changes time_freq to a 64bit value and makes it static (the only outside
user had no real need to modify it).  Intermediate values were already 64bit,
so the change isn't that big, but it saves a little in shifts by replacing
SHIFT_NSEC with TICK_LENGTH_SHIFT.  PPM_SCALE is then used to convert between
user space and kernel space representation.

Signed-off-by: Roman Zippel <zippel@linux-m68k.org>
Cc: john stultz <johnstul@us.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-05-01 08:03:58 -07:00
Roman Zippel
eea83d896e ntp: NTP4 user space bits update
This adds a few more things from the ntp nanokernel related to user space.
It's now possible to select the resolution used of some values via STA_NANO
and the kernel reports in which mode it works (pll/fll).

If some values for adjtimex() are outside the acceptable range, they are now
simply normalized instead of letting the syscall fail.  I removed
MOD_CLKA/MOD_CLKB as the mapping didn't really makes any sense, the kernel
doesn't support setting the clock.

Signed-off-by: Roman Zippel <zippel@linux-m68k.org>
Cc: john stultz <johnstul@us.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-05-01 08:03:58 -07:00
Roman Zippel
10a398d04c time: remove obsolete CLOCK_TICK_ADJUST
The first version of the ntp_interval/tick_length inconsistent usage patch was
recently merged as bbe4d18ac2

http://git.kernel.org/gitweb.cgi?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=bbe4d18ac2e058c56adb0cd71f49d9ed3216a405

While the fix did greatly improve the situation, it was correctly pointed out
by Roman that it does have a small bug: If the users change clocksources after
the system has been running and NTP has made corrections, the correctoins made
against the old clocksource will be applied against the new clocksource,
causing error.

The second attempt, which corrects the issue in the NTP_INTERVAL_LENGTH
definition has also made it up-stream as commit
e13a2e61dd

http://git.kernel.org/gitweb.cgi?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=e13a2e61dd5152f5499d2003470acf9c838eab84

Roman has correctly pointed out that CLOCK_TICK_ADJUST is calculated
based on the PIT's frequency, and isn't really relevant to non-PIT
driven clocksources (that is, clocksources other then jiffies and pit).

This patch reverts both of those changes, and simply removes
CLOCK_TICK_ADJUST.

This does remove the granularity error correction for users of PIT and Jiffies
clocksource users, but the granularity error but for the majority of users, it
should be within the 500ppm range NTP can accommodate for.

For systems that have granularity errors greater then 500ppm, the
"ntp_tick_adj=" boot option can be used to compensate.

[johnstul@us.ibm.com: provided changelog]
[mattilinnanvuori@yahoo.com: maek ntp_tick_adj static]
Signed-off-by: Roman Zippel <zippel@linux-m68k.org>
Acked-by: john stultz <johnstul@us.ibm.com>
Signed-off-by: Matti Linnanvuori <mattilinnanvuori@yahoo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: mingo@elte.hu
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-03-09 08:42:57 +01:00
john stultz
e13a2e61dd ntp: correct inconsistent interval/tick_length usage
clocksource initialization and error accumulation.  This corrects a 280ppm
drift seen on some systems using acpi_pm, and affects other clocksources as
well (likely to a lesser degree).

Signed-off-by: John Stultz <johnstul@us.ibm.com>
Cc: Roman Zippel <zippel@linux-m68k.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-02-10 10:48:03 +01:00
Andrew Morton
941e492bdb read_current_timer() cleanups
- All implementations can be __devinit

- The function prototypes were in asm/timex.h but they all must be the same,
  so create a single declaration in linux/timex.h.

- uninline the sparc64 version to match the other architectures

- Don't bother #defining ARCH_HAS_READ_CURRENT_TIMER to a particular value.

[ezk@cs.sunysb.edu: fix build]
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Haavard Skinnemoen <hskinnemoen@atmel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-06 10:41:02 -08:00
John Stultz
52bfb36050 time: add ADJ_OFFSET_SS_READ
Michael Kerrisk reported that a long standing bug in the adjtimex()
system call causes glibc's adjtime(3) function to deliver the wrong
results if 'delta' is NULL.

add the ADJ_OFFSET_SS_READ API detail, which will be used by glibc
to fix this API compatibility bug.

Also see: http://bugzilla.kernel.org/show_bug.cgi?id=6761

[ mingo@elte.hu: added patch description and made it backwards compatible ]

NOTE: the new flag is defined 0xa001 so that it returns -EINVAL on
older kernels - this way glibc can use it safely. Suggested by Ulrich
Drepper.

Acked-by: Ulrich Drepper <drepper@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2007-11-26 20:42:19 +01:00
Bob Picco
1f564ad6d4 [IA64] remove time interpolator
Remove time_interpolator code (This is generic code, but
only user was ia64.  It has been superseded by the
CONFIG_GENERIC_TIME code).

Signed-off-by: Bob Picco <bob.picco@hp.com>
Signed-off-by: John Stultz <johnstul@us.ibm.com>
Signed-off-by: Peter Keilty <peter.keilty@hp.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
2007-07-20 11:23:02 -07:00
john stultz
f4304ab215 [PATCH] HZ free ntp
Distangle the NTP update from HZ.  This is necessary for dynamic tick enabled
kernels.

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: john stultz <johnstul@us.ibm.com>
Cc: Roman Zippel <zippel@linux-m68k.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-02-16 08:13:56 -08:00
Helge Deller
3db5db4fcd [PATCH] use cycle_t instead of u64 in struct time_interpolator
The 32bit and 64bit PARISC Linux kernels suffers from the problem, that the
gettimeofday() call sometimes returns non-monotonic times.

The easiest way to fix this, is to drop the PARISC-specific implementation
and switch over to the generic TIME_INTERPOLATION framework.

But in order to make it even compile on 32bit PARISC, the patch below which
touches the generic Linux code, is mandatory.

More information and the full patch with the parisc-specific changes is included in this thread: http://lists.parisc-linux.org/pipermail/parisc-linux/2006-December/031003.html

As far as I could see, this patch does not change anything for the existing
architectures which use this framework (IA64 and SPARC64), since "cycles_t"
is defined there as unsigned 64bit-integer anyway (which then makes this
patch a no-change for them).

Signed-off-by: Helge Deller <deller@gmx.de>
Cc: <linux-arch@vger.kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-02-11 10:51:31 -08:00
Roman Zippel
7236e978a3 [PATCH] provide tickadj define
Provide a tickadj compatibility define for archs still using it.

Signed-off-by: Roman Zippel <zippel@linux-m68k.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-10-06 08:53:40 -07:00
Adrian Bunk
70bc42f90a [PATCH] kernel/time/ntp.c: possible cleanups
This patch contains the following possible cleanups:
- make the following needlessly global function static:
  - ntp_update_frequency()
- make the following needlessly global variables static:
  - time_state
  - time_offset
  - time_constant
  - time_reftime
- remove the following read-only global variable:
  - time_precision

Signed-off-by: Adrian Bunk <bunk@stusta.de>
Cc: Roman Zippel <zippel@linux-m68k.org>
Cc: john stultz <johnstul@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-10-01 00:39:27 -07:00
Roman Zippel
0883d899ef [PATCH] ntp: cleanup defines and comments
Remove a few unused defines and remove obsolete information from comments.

Signed-off-by: Roman Zippel <zippel@linux-m68k.org>
Cc: john stultz <johnstul@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-10-01 00:39:27 -07:00
Roman Zippel
f199239373 [PATCH] ntp: convert to the NTP4 reference model
This converts the kernel ntp model into a model which matches the nanokernel
reference implementations.  The previous patches already increased the
resolution and precision of the computations, so that this conversion becomes
quite simple.

<linux@horizon.com> explains:

The original NTP kernel interface was defined in units of microseconds.
That's what Linux implements.  As computers have gotten faster and can now
split microseconds easily, a new kernel interface using nanosecond units was
defined ("the nanokernel", confusing as that name is to OS hackers), and
there's an STA_NANO bit in the adjtimex() status field to tell the application
which units it's using.

The current ntpd supports both, but Linux loses some possible timing
resolution because of quantization effects, and the ntpd hackers would really
like to be able to drop the backwards compatibility code.

Ulrich Windl has been maintaining a patch set to do the conversion for years,
but it's hard to keep in sync.

Signed-off-by: Roman Zippel <zippel@linux-m68k.org>
Cc: john stultz <johnstul@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-10-01 00:39:27 -07:00
Roman Zippel
04b617e71e [PATCH] ntp: convert time_freq to nsec value
This converts time_freq to a scaled nsec value and adds around 6bit of extra
resolution.  This pushes the time_freq to its 32bit limits so the calculatons
have to be done with 64bit.

Signed-off-by: Roman Zippel <zippel@linux-m68k.org>
Cc: john stultz <johnstul@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-10-01 00:39:27 -07:00
Roman Zippel
97eebe138c [PATCH] ntp: remove time_tolerance
time_tolerance isn't changed at all in the kernel, so simply remove it, this
simplifies the next patch, as it avoids a number of conversions.

Signed-off-by: Roman Zippel <zippel@linux-m68k.org>
Cc: john stultz <johnstul@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-10-01 00:39:26 -07:00
Roman Zippel
8f807f8d21 [PATCH] ntp: add time_adjust to tick length
This folds update_ntp_one_tick() into second_overflow() and adds time_adjust
to the tick length, this makes time_next_adjust unnecessary.  This slightly
changes the adjtime() behaviour, instead of applying it to the next tick, it's
applied to the next second.

Signed-off-by: Roman Zippel <zippel@linux-m68k.org>
Cc: john stultz <johnstul@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-10-01 00:39:26 -07:00
Roman Zippel
3d3675cc3d [PATCH] ntp: prescale time_offset
This converts time_offset into a scaled per tick value.  This avoids now
completely the crude compensation in second_overflow().

Signed-off-by: Roman Zippel <zippel@linux-m68k.org>
Cc: john stultz <johnstul@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-10-01 00:39:26 -07:00
Roman Zippel
b0ee75561b [PATCH] ntp: add ntp_update_frequency
This introduces ntp_update_frequency() and deinlines ntp_clear() (as it's not
performance critical).  ntp_update_frequency() calculates the base tick length
using tick_usec and adds a base adjustment, in case the frequency doesn't
divide evenly by HZ.

Signed-off-by: Roman Zippel <zippel@linux-m68k.org>
Cc: john stultz <johnstul@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-10-01 00:39:26 -07:00
john stultz
4c7ee8de95 [PATCH] NTP: Move all the NTP related code to ntp.c
Move all the NTP related code to ntp.c

[akpm@osdl.org: cleanups, build fix]
Signed-off-by: John Stultz <johnstul@us.ibm.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Roman Zippel <zippel@linux-m68k.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-10-01 00:39:26 -07:00
David Woodhouse
ee6baf884b [PATCH] headers_check: remove <asm/timex.h> from user export
There's useful stuff in <linux/timex.h> but <asm/timex.h> has nothing for
userspace.  Stop exporting it, and include it only from within the existing
#ifdef __KERNEL__ part of <linux/timex.h>

This fixes a 'make headers_check' failure on i386 because asm-i386/timex.h
includes both asm-i386/tsc.h and asm-i386/processor.h, neither of which are
exported to userspace.  It's not entirely clear _why_ it includes either of
these, but it does.

Signed-off-by: David Woodhouse <dwmw2@infradead.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-09-13 07:32:15 -07:00
Roman Zippel
19923c190e [PATCH] fix and optimize clock source update
This fixes the clock source updates in update_wall_time() to correctly
track the time coming in via current_tick_length().  Optimize the fast
paths to be as short as possible to keep the overhead low.

Signed-off-by: Roman Zippel <zippel@linux-m68k.org>
Acked-by: John Stultz <johnstul@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-26 09:58:21 -07:00
john stultz
260a42309b [PATCH] Time: Let user request precision from current_tick_length()
Change the current_tick_length() function so it takes an argument which
specifies how much precision to return in shifted nanoseconds.  This provides
a simple way to convert between NTPs internal nanoseconds shifted by
(SHIFT_SCALE - 10) to other shifted nanosecond units that are used by the
clocksource abstraction.

Signed-off-by: John Stultz <johnstul@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-26 09:58:20 -07:00
David Woodhouse
62c4f0a2d5 Don't include linux/config.h from anywhere else in include/
Signed-off-by: David Woodhouse <dwmw2@infradead.org>
2006-04-26 12:56:16 +01:00
Stephen Rothwell
3158e9411a [PATCH] consolidate sys32/compat_adjtimex
Create compat_sys_adjtimex and use it an all appropriate places.

Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Arnd Bergmann <arnd@arndb.de>
Acked-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-26 08:56:57 -08:00
Roman Zippel
5ddcfa878d [PATCH] remove pps support
This removes the support for pps.  It's completely unused within the kernel
and is basically in the way for further cleanups.  It should be easier to
readd proper support for it after the rest has been converted to NTP4
(where the pps mechanisms are quite different from NTP3 anyway).

Signed-off-by: Roman Zippel <zippel@linux-m68k.org>
Cc: Adrian Bunk <bunk@stusta.de>
Cc: john stultz <johnstul@us.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-25 08:23:02 -08:00
Paul Mackerras
726c14bf49 [PATCH] Provide an interface for getting the current tick length
This provides an interface for arch code to find out how many
nanoseconds are going to be added on to xtime by the next call to
do_timer.  The value returned is a fixed-point number in 52.12 format
in nanoseconds.  The reason for this format is that it gives the
full precision that the timekeeping code is using internally.

The motivation for this is to fix a problem that has arisen on 32-bit
powerpc in that the value returned by do_gettimeofday drifts apart
from xtime if NTP is being used.  PowerPC is now using a lockless
do_gettimeofday based on reading the timebase register and performing
some simple arithmetic.  (This method of getting the time is also
exported to userspace via the VDSO.)  However, the factor and offset
it uses were calculated based on the nominal tick length and weren't
being adjusted when NTP varied the tick length.

Note that 64-bit powerpc has had the lockless do_gettimeofday for a
long time now.  It also had an extremely hairy routine that got called
from the 32-bit compat routine for adjtimex, which adjusted the
factor and offset according to what it thought the timekeeping code
was going to do.  Not only was this only called if a 32-bit task did
adjtimex (i.e. not if a 64-bit task did adjtimex), it was also
duplicating computations from kernel/timer.c and it wasn't clear that
it was (still) correct.

The simple solution is to ask the timekeeping code how long the
current jiffy will be on each timer interrupt, after calling
do_timer.  If this jiffy will be a different length from the last one,
we then need to compute new values for the factor and offset used in
the lockless do_gettimeofday.  In this way we can keep xtime and
do_gettimeofday in sync, even when NTP is varying the tick length.

Note that when adjtimex varies the tick length, it almost always
introduces the variation from the next tick on.  The only case I could
see where adjtimex would vary the length of the current tick is when
an old-style adjtime adjustment is being cancelled.  (It's not clear
to me why the adjustment has to be cancelled immediately rather than
from the next tick on.)  Thus I don't see any real need for a hook in
adjtimex; the rare case of an old-style adjustment being cancelled can
be fixed up at the next tick.

Signed-off-by: Paul Mackerras <paulus@samba.org>
Acked-by: john stultz <johnstul@us.ibm.com>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-02-17 08:24:29 -08:00
john stultz
1bb34a4127 [PATCH] NTP shift_right cleanup
Create a macro shift_right() that avoids the numerous ugly conditionals in the
NTP code that look like:

        if(a < 0)
                b = -(-a >> shift);
        else
                b = a >> shift;

Replacing it with:

        b = shift_right(a, shift);

This should have zero effect on the logic, however it should probably have
a bit of testing just to be sure.

Also replace open-coded min/max with the macros.

Signed-off-by : John Stultz <johnstul@us.ibm.com>

Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-30 17:37:18 -08:00