linux-stable.git/kernel/time/ntp.c, branch v2.6.38

ntp: add hardpps implementation

2011-01-13T16:03:20+00:00

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 
Acked-by: John Stultz 
Cc: Rodolfo Giometti 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

ntp: Clamp PLL update interval

2010-09-09T18:48:37+00:00

Clamp update interval to reduce PLL gain with low sampling rate (e.g.
intermittent network connection) to avoid instability.

The clamp roughly corresponds to the loop time constant, it's 8 * poll
interval for SHIFT_PLL 2 and 32 * poll interval for SHIFT_PLL 4. This
gives good results without affecting the gain in normal conditions where
ntpd skips only up to seven consecutive samples.

Signed-off-by: Miroslav Lichvar 
Acked-by: john stultz 
LKML-Reference: <1283870626-9472-1-git-send-email-mlichvar@redhat.com>
Signed-off-by: Thomas Gleixner

ntp: Make time_adjust static

2010-03-23T16:19:37+00:00

Now that no arches are accessing time_adjust directly,
make it static.

Signed-off-by: John Stultz 
LKML-Reference: <1268968769-19209-1-git-send-email-johnstul@us.ibm.com>
Signed-off-by: Thomas Gleixner

ntp: Cleanup xtime references in ntp.c

2010-01-29T09:15:19+00:00

ntp.c doesn't need to access timekeeping internals directly, so change
xtime references to use the get_seconds() timekeeping interface.

Signed-off-by: John Stultz 
Cc: richard@rsk.demon.co.uk
LKML-Reference: <1264738844-21935-1-git-send-email-johnstul@us.ibm.com>
Signed-off-by: Thomas Gleixner

ntp: Make time_esterror and time_maxerror static

2010-01-29T09:15:19+00:00

Make time_esterror and time_maxerror static as no one uses them
outside of ntp.c
    
Signed-off-by: John Stultz 
Cc: richard@rsk.demon.co.uk
LKML-Reference: <1264719761.3437.47.camel@localhost.localdomain>
Signed-off-by: Thomas Gleixner

timekeeping: Introduce timekeeping_leap_insert

2009-08-15T08:55:45+00:00

Move the adjustment of xtime, wall_to_monotonic and the update of the
vsyscall variables to the timekeeping code.

Signed-off-by: John Stultz 
Signed-off-by: Martin Schwidefsky 
LKML-Reference: <20090814134807.609730216@de.ibm.com>
Signed-off-by: Thomas Gleixner

time: ntp: fix bug in ntp_update_offset() & do_adjtimex(), fix

2009-02-26T18:39:47+00:00

The time_status conditional was accidentally placed right after we clear
the checked time_status bits, which causes us to take the conditional
every time through. This fixes it by moving the conditional to before we
clear the time_status bits.

Signed-off-by: John Stultz 
Cc: Clark Williams 
Signed-off-by: Ingo Molnar

time: ntp: clean up second_overflow()

2009-02-25T17:38:17+00:00

Impact: cleanup, no functionality changed

The 'time_adj' local variable is named in a very confusing
way because it almost shadows the 'time_adjust' global
variable - which is used in this same function.

Rename it to 'delta' - to make them stand apart more clearly.

kernel/time/ntp.o:

   text	   data	    bss	    dec	    hex	filename
   2545	    114	    144	   2803	    af3	ntp.o.before
   2545	    114	    144	   2803	    af3	ntp.o.after

md5:
   1bf0b3be564512279ba7cee299d1d2be  ntp.o.before.asm
   1bf0b3be564512279ba7cee299d1d2be  ntp.o.after.asm

Signed-off-by: Ingo Molnar

time: ntp: simplify ntp_tick_adj calculations

2009-02-25T17:38:16+00:00

Impact: micro-optimization

Convert the (internal) ntp_tick_adj value we store from unscaled
units to scaled units. This is a constant that we never modify,
so scaling it up once during bootup is enough - we dont have to
do it for every adjustment step.

Signed-off-by: Ingo Molnar

time: ntp: make 64-bit constants more robust

2009-02-25T17:38:15+00:00

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