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| author | Roman Zippel <zippel@linux-m68k.org> | 2008-05-01 04:34:36 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2008-05-01 08:03:58 -0700 |
| commit | 9f14f669d18477fe3df071e2fa4da36c00acee8e (patch) | |
| tree | 84b5600017902ced77ee0cb9a4bc21a6768d22e5 /include/linux/timex.h | |
| parent | 074b3b87941c99bc0ce35385b5817924b1ed0c23 (diff) | |
| download | lwn-9f14f669d18477fe3df071e2fa4da36c00acee8e.tar.gz lwn-9f14f669d18477fe3df071e2fa4da36c00acee8e.zip | |
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>
Diffstat (limited to 'include/linux/timex.h')
| -rw-r--r-- | include/linux/timex.h | 9 |
1 files changed, 2 insertions, 7 deletions
diff --git a/include/linux/timex.h b/include/linux/timex.h index 48c3376dce71..9fbdd12a52f1 100644 --- a/include/linux/timex.h +++ b/include/linux/timex.h @@ -76,27 +76,22 @@ #define MAXTC 10 /* maximum time constant (shift) */ /* - * The SHIFT_UPDATE define establishes the decimal point of the - * time_offset variable which represents the current offset with - * respect to standard time. - * * SHIFT_USEC defines the scaling (shift) of the time_freq and * time_tolerance variables, which represent the current frequency * offset and maximum frequency tolerance. */ -#define SHIFT_UPDATE (SHIFT_HZ + 1) /* time offset scale (shift) */ #define SHIFT_USEC 16 /* frequency offset scale (shift) */ #define PPM_SCALE (NSEC_PER_USEC << (TICK_LENGTH_SHIFT - SHIFT_USEC)) #define PPM_SCALE_INV_SHIFT 20 #define PPM_SCALE_INV ((1ll << (PPM_SCALE_INV_SHIFT + TICK_LENGTH_SHIFT)) / \ PPM_SCALE + 1) -#define MAXPHASE 512000L /* max phase error (us) */ +#define MAXPHASE 500000000l /* max phase error (ns) */ #define MAXFREQ 500000 /* max frequency error (ns/s) */ #define MAXFREQ_SCALED ((s64)MAXFREQ << TICK_LENGTH_SHIFT) #define MINSEC 256 /* min interval between updates (s) */ #define MAXSEC 2048 /* max interval between updates (s) */ -#define NTP_PHASE_LIMIT (MAXPHASE << 5) /* beyond max. dispersion */ +#define NTP_PHASE_LIMIT ((MAXPHASE / NSEC_PER_USEC) << 5) /* beyond max. dispersion */ /* * syscall interface - used (mainly by NTP daemon) |