summaryrefslogtreecommitdiff
path: root/include/linux/timex.h
AgeCommit message (Collapse)Author
2010-01-29ntp: Make time_esterror and time_maxerror staticjohn stultz
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>
2009-12-08Merge branches 'timers-for-linus-ntp' and 'irq-core-for-linus' of ↵Linus Torvalds
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
2009-10-05time: Implement logarithmic time accumulationjohn stultz
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>
2009-08-28ntp: Provide compability defines (You say MOD_NANO, I say ADJ_NANO)john stultz
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>
2009-06-16time: move PIT_TICK_RATE to linux/timex.hArnd Bergmann
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>
2009-05-12ntp: fix comment typosjohn stultz
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>
2009-05-06ntp: adjust SHIFT_PLL to improve NTP convergencejohn stultz
The conversion to the ntpv4 reference model f19923937321244e7dc334767eb4b67e0e3d5c74 ("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>
2009-02-25time: ntp: make 64-bit constants more robustIngo Molnar
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>
2008-12-12linux/timex.h: cleanup for userspaceMike Frysinger
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>
2008-09-24ntp: improve adjtimex frequency roundingRoman Zippel
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>
2008-08-22ntp: fix ADJ_OFFSET_SS_READ bug and do_adjtimex() cleanupRoman Zippel
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>
2008-05-01ntp: handle leap second via timerRoman Zippel
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>
2008-05-01ntp: remove current_tick_length()Roman Zippel
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>
2008-05-01ntp: rename TICK_LENGTH_SHIFT to NTP_SCALE_SHIFTRoman Zippel
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>
2008-05-01ntp: support for TAIRoman Zippel
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>
2008-05-01ntp: increase time_offset resolutionRoman Zippel
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>
2008-05-01ntp: increase time_freq resolutionRoman Zippel
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>
2008-05-01ntp: NTP4 user space bits updateRoman Zippel
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>
2008-03-09time: remove obsolete CLOCK_TICK_ADJUSTRoman Zippel
The first version of the ntp_interval/tick_length inconsistent usage patch was recently merged as bbe4d18ac2e058c56adb0cd71f49d9ed3216a405 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 e13a2e61dd5152f5499d2003470acf9c838eab84 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>
2008-02-10ntp: correct inconsistent interval/tick_length usagejohn stultz
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>
2008-02-06read_current_timer() cleanupsAndrew Morton
- 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>
2007-11-26time: add ADJ_OFFSET_SS_READJohn Stultz
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>
2007-07-20[IA64] remove time interpolatorBob Picco
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>
2007-02-16[PATCH] HZ free ntpjohn stultz
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>
2007-02-11[PATCH] use cycle_t instead of u64 in struct time_interpolatorHelge Deller
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>
2006-10-06[PATCH] provide tickadj defineRoman Zippel
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>
2006-10-01[PATCH] kernel/time/ntp.c: possible cleanupsAdrian Bunk
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[PATCH] ntp: cleanup defines and commentsRoman Zippel
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[PATCH] ntp: convert to the NTP4 reference modelRoman Zippel
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[PATCH] ntp: convert time_freq to nsec valueRoman Zippel
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[PATCH] ntp: remove time_toleranceRoman Zippel
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[PATCH] ntp: add time_adjust to tick lengthRoman Zippel
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[PATCH] ntp: prescale time_offsetRoman Zippel
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[PATCH] ntp: add ntp_update_frequencyRoman Zippel
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[PATCH] NTP: Move all the NTP related code to ntp.cjohn stultz
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>
2006-09-13[PATCH] headers_check: remove <asm/timex.h> from user exportDavid Woodhouse
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>
2006-06-26[PATCH] fix and optimize clock source updateRoman Zippel
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[PATCH] Time: Let user request precision from current_tick_length()john stultz
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>
2006-04-26Don't include linux/config.h from anywhere else in include/David Woodhouse
Signed-off-by: David Woodhouse <dwmw2@infradead.org>
2006-03-26[PATCH] consolidate sys32/compat_adjtimexStephen Rothwell
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>
2006-03-25[PATCH] remove pps supportRoman Zippel
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>
2006-02-17[PATCH] Provide an interface for getting the current tick lengthPaul Mackerras
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>
2005-10-30[PATCH] NTP shift_right cleanupjohn stultz
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>
2005-09-07[PATCH] NTP: ntp-helper functionsjohn stultz
This patch cleans up a commonly repeated set of changes to the NTP state variables by adding two helper inline functions: ntp_clear(): Clears the ntp state variables ntp_synced(): Returns 1 if the system is synced with a time server. This was compile tested for alpha, arm, i386, x86-64, ppc64, s390, sparc, sparc64. 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>
2005-03-11[PATCH] Make lots of things staticAdrian Bunk
This is a megarollup of ~60 patches which give various things static scope. Signed-off-by: Adrian Bunk <bunk@stusta.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2004-10-31[PATCH] fix IBM cyclone clock and some cleanupChristoph Lameter
- fix broken IBM cyclone time interpolator support - add support for cyclic timers through an addition of a mask in the timer interpolator structure - Allow time_interpolator_update() and time_interpolator_get_offset() to be invoked without an active time interpolator (necessary since the cyclone clock is initialized late in ACPI processing) - remove obsolete function time_interpolator_resolution() - add a mask to all struct time_interpolator setups in the kernel - Make time interpolators work on 32bit platforms Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2004-10-18[PATCH] cleanup: time.h, times.h, timex.h and jiffies.hMartin Schwidefsky
This patch moves some definitions among time.h, times.h, timex.h and jiffies.h. The purpose is to sort all jiffies related functions to jiffies.h, to get rid of the cyclic dependency between time.h & timex.h and to move all #include lines to the start of the header files. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2004-10-02[PATCH] ppc: time interpolator build fixChristoph Lameter
Remove two leftover #includes from timex.h which may cause a build failure for ppc. Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2004-09-07[PATCH] Time interpolator: Scalability enhancements and high resolution time ↵Christoph Lameter
for IA64 This has been in the ia64 (and hence -mm) trees for a couple of months. Changelog: * Affects only architectures which define CONFIG_TIME_INTERPOLATION (currently only IA64) * Genericize time interpolation, make time interpolators easily usable and provide instructions on how to use the interpolator for other architectures. * Provide nanosecond resolution for clock_gettime and an accuracy up to the time interpolator time base. * clock_getres() reports resolution of underlying time basis which is typically <50ns and may be 1ns on some systems. * Make time interpolator self-tuning to limit time jumps and to make the interpolators work correctly on systems with broken time base specifications. * SMP scalability: Make clock_gettime and gettimeofday scale O(1) by removing the cmpxchg for most clocks (tested for up to 512 CPUs) * IA64: provide asm fastcall that doubles the performance of gettimeofday and clock_gettime on SGI and other IA64 systems (asm fastcalls scale O(1) together with the scalability fixes). * IA64: provide nojitter kernel option so that IA64 systems with correctly synchronized ITC counters may also enjoy the scalability enhancements. Performance measurements for single calls (ITC cycles): A. 4 way Intel IA64 SMP system (kmart) ITC offsets: kmart:/usr/src/noship-tests # dmesg|grep synchr CPU 1: synchronized ITC with CPU 0 (last diff 1 cycles, maxerr 417 cycles) CPU 2: synchronized ITC with CPU 0 (last diff 2 cycles, maxerr 417 cycles) CPU 3: synchronized ITC with CPU 0 (last diff 1 cycles, maxerr 417 cycles) A.1. Current kernel code kmart:/usr/src/noship-tests # ./dmt gettimeofday cycles: 3737 220 215 215 215 215 215 215 215 215 clock_gettime(REAL) cycles: 4058 575 564 576 565 566 558 558 558 558 clock_gettime(MONO) cycles: 1583 621 609 609 609 609 609 609 609 609 clock_gettime(PROCESS) cycles: 71428 298 259 259 259 259 259 259 259 259 clock_gettime(THREAD) cycles: 3982 336 290 298 298 298 298 286 286 286 A.2 New code using cmpxchg kmart:/usr/src/noship-tests # ./dmt gettimeofday cycles: 3145 213 216 213 213 213 213 213 213 213 clock_gettime(REAL) cycles: 3185 230 210 210 210 210 210 210 210 210 clock_gettime(MONO) cycles: 284 217 217 216 216 216 216 216 216 216 clock_gettime(PROCESS) cycles: 68857 289 270 259 259 259 259 259 259 259 clock_gettime(THREAD) cycles: 3862 339 298 298 298 298 290 286 286 286 A.3 New code with cmpxchg switched off (nojitter kernel option) kmart:/usr/src/noship-tests # ./dmt gettimeofday cycles: 3195 219 219 212 212 212 212 212 212 212 clock_gettime(REAL) cycles: 3003 228 205 205 205 205 205 205 205 205 clock_gettime(MONO) cycles: 279 209 209 209 208 208 208 208 208 208 clock_gettime(PROCESS) cycles: 65849 292 259 259 268 270 270 259 259 259 B. SGI SN2 system running 512 IA64 CPUs. B.1. Current kernel code [root@ascender noship-tests]# ./dmt gettimeofday cycles: 17221 1028 1007 1004 1004 1004 1010 25928 1002 1003 clock_gettime(REAL) cycles: 10388 1099 1055 1044 1064 1063 1051 1056 1061 1056 clock_gettime(MONO) cycles: 2363 96 96 96 96 96 96 96 96 96 clock_gettime(PROCESS) cycles: 46537 804 660 666 666 666 666 666 666 666 clock_gettime(THREAD) cycles: 10945 727 710 684 685 686 685 686 685 686 B.2 New code ascender:~/noship-tests # ./dmt gettimeofday cycles: 3874 610 588 588 588 588 588 588 588 588 clock_gettime(REAL) cycles: 3893 612 588 582 588 588 588 588 588 588 clock_gettime(MONO) cycles: 686 595 595 588 588 588 588 588 588 588 clock_gettime(PROCESS) cycles: 290759 322 269 269 259 265 265 265 259 259 clock_gettime(THREAD) cycles: 5153 358 306 298 296 304 290 298 298 298 Scalability of time functions (in time it takes to do a million calls): ======================================================================= A. 4 way Intel IA SMP system (kmart) A.1 Current code kmart:/usr/src/noship-tests # ./todscale -n1000000 CPUS WALL WALL/CPUS 1 0.192 0.192 2 1.125 0.563 4 9.229 2.307 A.2 New code using cmpxchg kmart:/usr/src/noship-tests # ./todscale CPUS WALL WALL/CPUS 1 0.188 0.188 2 0.457 0.229 4 0.413 0.103 (the measurement with 4 cpus may fluctuate up to 15.x somehow) A.3 New code without cmpxchg (nojitter kernel option) kmart:/usr/src/noship-tests # ./todscale -n10000000 CPUS WALL WALL/CPUS 1 0.180 0.180 2 0.180 0.090 4 0.252 0.063 B. SGI SN2 system running 512 IA64 CPUs. The system has a global monotonic clock and therefore has no need for compensation. Current code uses a cmpxchg. New code has no cmpxchg. B.1 current code ascender:~/noship-tests # ./todscale CPUS WALL WALL/CPUS 1 0.850 0.850 2 1.767 0.884 4 6.124 1.531 8 20.777 2.597 16 57.693 3.606 32 164.688 5.146 64 456.647 7.135 128 1093.371 8.542 256 2778.257 10.853 (System crash at 512 CPUs) B.2 New code ascender:~/noship-tests # ./todscale -n1000000 CPUS WALL WALL/CPUS 1 0.426 0.426 2 0.429 0.215 4 0.436 0.109 8 0.452 0.057 16 0.454 0.028 32 0.457 0.014 64 0.459 0.007 128 0.466 0.004 256 0.474 0.002 512 0.518 0.001 Clock Accuracy ============== A. 4 CPU SMP system A.1 Old code kmart:/usr/src/noship-tests # ./cdisp Gettimeofday() = 1092124757.270305000 CLOCK_REALTIME= 1092124757.270382000 resolution= 0.000976563 CLOCK_MONOTONIC= 89.696726590 resolution= 0.000976563 CLOCK_PROCESS_CPUTIME_ID= 0.001242507 resolution= 0.000000001 CLOCK_THREAD_CPUTIME_ID= 0.001255310 resolution= 0.000000001 A.2 New code kmart:/usr/src/noship-tests # ./cdisp Gettimeofday() = 1092124478.194530000 CLOCK_REALTIME= 1092124478.194603399 resolution= 0.000000001 CLOCK_MONOTONIC= 88.198315204 resolution= 0.000000001 CLOCK_PROCESS_CPUTIME_ID= 0.001241235 resolution= 0.000000001 CLOCK_THREAD_CPUTIME_ID= 0.001254747 resolution= 0.000000001 Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2003-10-21[PATCH] Time precision, adjtime(x) vs. gettimeofdayAndrew Morton
From: Stephen Hemminger <shemminger@osdl.org> The following will prevent adjtime from causing time regression. It delays starting the adjtime mechanism for one tick, and keeps gettimeofday inside the window. Only fixes i386, but changes to other arch would be similar. Running a simple clock test program and playing with adjtime demonstrates that this fixes the problem (and 2.6.0-test6 is broken). But given the fragile nature of the timer code, it should go through some more testing before inclusion.
generated by cgit v1.2.3 (git 2.46.0) at 2026-01-15 07:15:05 +0000