19 Dec, 2011
1 commit
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Fix various KernelDoc build warnings.
Signed-off-by: Kusanagi Kouichi
Cc: John Stultz
Link: http://lkml.kernel.org/r/20111219091320.0D5AF6FC03D@msa105.auone-net.jp
Signed-off-by: Ingo Molnar
11 Nov, 2011
1 commit
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For some frequencies, the clocks_calc_mult_shift() function will
unfortunately select mult values very close to 0xffffffff. This
has the potential to overflow when NTP adjusts the clock, adding
to the mult value.This patch adds a clocksource.maxadj value, which provides
an approximation of an 11% adjustment(NTP limits adjustments to
500ppm and the tick adjustment is limited to 10%), which could
be made to the clocksource.mult value. This is then used to both
check that the current mult value won't overflow/underflow, as
well as warning us if the timekeeping_adjust() code pushes over
that 11% boundary.v2: Fix max_adjustment calculation, and improve WARN_ONCE
messages.v3: Don't warn before maxadj has actually been set
CC: Yong Zhang
CC: David Daney
CC: Thomas Gleixner
CC: Chen Jie
CC: zhangfx
CC: stable@kernel.org
Reported-by: Chen Jie
Reported-by: zhangfx
Tested-by: Yong Zhang
Signed-off-by: John Stultz
23 Jul, 2011
1 commit
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* 'x86-vdso-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
x86-64, vdso: Do not allocate memory for the vDSO
clocksource: Change __ARCH_HAS_CLOCKSOURCE_DATA to a CONFIG option
x86, vdso: Drop now wrong comment
Document the vDSO and add a reference parser
ia64: Replace clocksource.fsys_mmio with generic arch data
x86-64: Move vread_tsc and vread_hpet into the vDSO
clocksource: Replace vread with generic arch data
x86-64: Add --no-undefined to vDSO build
x86-64: Allow alternative patching in the vDSO
x86: Make alternative instruction pointers relative
x86-64: Improve vsyscall emulation CS and RIP handling
x86-64: Emulate legacy vsyscalls
x86-64: Fill unused parts of the vsyscall page with 0xcc
x86-64: Remove vsyscall number 3 (venosys)
x86-64: Map the HPET NX
x86-64: Remove kernel.vsyscall64 sysctl
x86-64: Give vvars their own page
x86-64: Document some of entry_64.S
x86-64: Fix alignment of jiffies variable
22 Jul, 2011
1 commit
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The machinery for __ARCH_HAS_CLOCKSOURCE_DATA assumed a file in
asm-generic would be the default for architectures without their own
file in asm/, but that is not how it works.Replace it with a Kconfig option instead.
Link: http://lkml.kernel.org/r/4E288AA6.7090804@zytor.com
Signed-off-by: H. Peter Anvin
Cc: Andy Lutomirski
Cc: Arnd Bergmann
Cc: Tony Luck
15 Jul, 2011
1 commit
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Now that clocksource.archdata is available, use it for ia64-specific
code.Cc: Clemens Ladisch
Cc: linux-ia64@vger.kernel.org
Cc: Tony Luck
Cc: Fenghua Yu
Cc: John Stultz
Cc: Thomas Gleixner
Signed-off-by: Andy Lutomirski
Link: http://lkml.kernel.org/r/d31de0ee0842a0e322fb6441571c2b0adb323fa2.1310563276.git.luto@mit.edu
Signed-off-by: H. Peter Anvin
14 Jul, 2011
1 commit
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The vread field was bloating struct clocksource everywhere except
x86_64, and I want to change the way this works on x86_64, so let's
split it out into per-arch data.Cc: x86@kernel.org
Cc: Clemens Ladisch
Cc: linux-ia64@vger.kernel.org
Cc: Tony Luck
Cc: Fenghua Yu
Cc: John Stultz
Cc: Thomas Gleixner
Signed-off-by: Andy Lutomirski
Link: http://lkml.kernel.org/r/3ae5ec76a168eaaae63f08a2a1060b91aa0b7759.1310563276.git.luto@mit.edu
Signed-off-by: H. Peter Anvin
17 Jun, 2011
1 commit
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The clocksource watchdog code is interruptible and it has been
observed that this can trigger false positives which disable the TSC.The reason is that an interrupt storm or a long running interrupt
handler between the read of the watchdog source and the read of the
TSC brings the two far enough apart that the delta is larger than the
unstable treshold. Move both reads into a short interrupt disabled
region to avoid that.Reported-and-tested-by: Vernon Mauery
Signed-off-by: Thomas Gleixner
Cc: stable@kernel.org
24 May, 2011
1 commit
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Add a generic mmio clocksource, covering both 32-bit and 16-bit register
access sizes, for up or down counters. This can be used to easily
create clocksources for simple counter-based implementations.Cc: Alessandro Rubini
Cc: Colin Cross
Cc: Eric Miao
Cc: Erik Gilling
Acked-by: "Hans J. Koch"
Cc: Imre Kaloz
Cc: Krzysztof Halasa
Cc: Kukjin Kim
Cc: Lennert Buytenhek
Cc: Linus Walleij
Cc: linux-omap@vger.kernel.org
Acked-by: Nicolas Pitre
Cc: Olof Johansson
Tested-by: Sascha Hauer
Reviewed-by: Thomas Gleixner
Tested-by: Tony Lindgren
Reviewed-by: Viresh Kumar
Cc: Wan ZongShun
Signed-off-by: Russell King
19 May, 2011
1 commit
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Group the hot path members of struct clocksource together so we have a
better cache line footprint. Make it cacheline aligned.Signed-off-by: Thomas Gleixner
Cc: John Stultz
Cc: Eric Dumazet
Reviewed-by: Ingo Molnar
Link: http://lkml.kernel.org/r/%3C20110518210136.003081882%40linutronix.de%3E
14 May, 2011
2 commits
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…into timers/clocksource
Conflicts:
arch/ia64/kernel/cyclone.c
arch/mips/kernel/i8253.c
arch/x86/kernel/i8253.cReason: Resolve conflicts so further cleanups do not conflict further
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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Convert the footbridge isa-timer code to use generic i8253 clocksource.
Acked-by: John Stultz
Acked-by: Thomas Gleixner
Signed-off-by: Russell King
22 Feb, 2011
1 commit
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As nothing should be writing to the clocksource name string, make the
clocksource name pointer const. Build-tested on ARM Versatile Express.Signed-off-by: Russell King
Signed-off-by: John Stultz
27 Jul, 2010
2 commits
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To properly handle clocksources that change frequencies
at the clocksource->enable() point, this patch adds
a method that will update the clocksource's mult/shift and
max_idle_ns values.Signed-off-by: John Stultz
LKML-Reference:
Signed-off-by: Thomas Gleixner -
update_vsyscall() did not provide the wall_to_monotoinc offset,
so arch specific implementations tend to reference wall_to_monotonic
directly. This limits future cleanups in the timekeeping core, so
this patch fixes the update_vsyscall interface to provide
wall_to_monotonic, allowing wall_to_monotonic to be made static
as planned in Documentation/feature-removal-schedule.txtSigned-off-by: John Stultz
Cc: Martin Schwidefsky
Cc: Anton Blanchard
Cc: Paul Mackerras
Cc: Tony Luck
LKML-Reference:
Signed-off-by: Thomas Gleixner
10 May, 2010
1 commit
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How to pick good mult/shift pairs has always been difficult to
describe to folks writing clocksource drivers, since it requires
careful tradeoffs in adjustment accuracy vs overflow limits.Now, with the clocks_calc_mult_shift function, its much
easier. However, not many clocksources have converted to using that
function, and there is still the issue of the max interval length
assumption being made by each clocksource driver independently.So this patch simplifies the registration process by having
clocksources be registered with a hz/khz value and the registration
function taking care of setting mult/shift.This should take most of the confusion out of writing a clocksource
driver.Additionally it also keeps the shift size tradeoff (more accuracy vs
longer possible nohz times) centralized so the timekeeping core can
keep track of the assumptions being made.[ tglx: Coding style and comments fixed ]
Signed-off-by: John Stultz
LKML-Reference:
Signed-off-by: Thomas Gleixner
05 Feb, 2010
2 commits
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Add a clocksource suspend callback. This callback can be used by the
clocksource driver to shutdown and perform any kind of late suspend
activities even though the clocksource driver itself is a non-sysdev
driver.One example where this is useful is to fix the sh_cmt.c platform driver
that today suspends using the platform bus and shuts down the clocksource
too early.With this callback in place the sh_cmt driver will suspend using the
clocksource and clockevent hooks and leave the platform device pm
callbacks unused.Signed-off-by: Magnus Damm
Cc: Paul Mundt
Cc: john stultz
Signed-off-by: Andrew Morton
Signed-off-by: Thomas Gleixner -
Pass the clocksource as an argument to the clocksource resume callback.
Needed so we can point out which CMT channel the sh_cmt.c driver shall
resume.Signed-off-by: Magnus Damm
Cc: john stultz
Cc: Paul Mundt
Signed-off-by: Andrew Morton
Signed-off-by: Thomas Gleixner
09 Dec, 2009
1 commit
-
…nel/git/tip/linux-2.6-tip
* 'timers-for-linus-urgent' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
hrtimer: Fix /proc/timer_list regression
itimers: Fix racy writes to cpu_itimer fields
timekeeping: Fix clock_gettime vsyscall time warp
17 Nov, 2009
1 commit
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Since commit 0a544198 "timekeeping: Move NTP adjusted clock multiplier
to struct timekeeper" the clock multiplier of vsyscall is updated with
the unmodified clock multiplier of the clock source and not with the
NTP adjusted multiplier of the timekeeper.This causes user space observerable time warps:
new CLOCK-warp maximum: 120 nsecs, 00000025c337c537 -> 00000025c337c4bfAdd a new argument "mult" to update_vsyscall() and hand in the
timekeeping internal NTP adjusted multiplier.Signed-off-by: Lin Ming
Cc: "Zhang Yanmin"
Cc: Martin Schwidefsky
Cc: Benjamin Herrenschmidt
Cc: Tony Luck
LKML-Reference:
Signed-off-by: Thomas Gleixner
14 Nov, 2009
2 commits
-
The dynamic tick allows the kernel to sleep for periods longer than a
single tick, but it does not limit the sleep time currently. In the
worst case the kernel could sleep longer than the wrap around time of
the time keeping clock source which would result in losing track of
time.Prevent this by limiting it to the safe maximum sleep time of the
current time keeping clock source. The value is calculated when the
clock source is registered.[ tglx: simplified the code a bit and massaged the commit msg ]
Signed-off-by: Jon Hunter
Cc: John Stultz
LKML-Reference:
Signed-off-by: Thomas Gleixner -
MIPS has two functions to calculcate the mult/shift factors for clock
sources and clock events at run time. ARM needs such functions as
well.Implement a function which calculates the mult/shift factors based on
the frequencies to which and from which is converted. The function
also has a parameter to specify the minimum conversion range in
seconds. This range is guaranteed not to produce a 64bit overflow when
a value is multiplied with the calculated mult factor. The larger the
conversion range the less becomes the conversion accuracy.Provide two inline wrappers which handle clock events and clock
sources. For clock events the "from" frequency is nano seconds per
second which corresponds to 1GHz and "to" is the device frequency. For
clock sources "from" is the device frequency and "to" is nano seconds
per second.Signed-off-by: Thomas Gleixner
Tested-by: Mikael Pettersson
Acked-by: Ralf Baechle
Acked-by: Linus Walleij
Cc: John Stultz
LKML-Reference:
29 Aug, 2009
1 commit
-
Martin Schwidefsky analyzed it:
To register a clocksource the clocksource_mutex is acquired and if
necessary timekeeping_notify is called to install the clocksource as
the timekeeper clock. timekeeping_notify uses stop_machine which needs
to take cpu_add_remove_lock mutex.
Starting a new cpu is done with the cpu_add_remove_lock mutex held.
native_cpu_up checks the tsc of the new cpu and if the tsc is no good
clocksource_change_rating is called. Which needs the clocksource_mutex
and the deadlock is complete.The solution is to replace the TSC via the clocksource watchdog
mechanism. Mark the TSC as unstable and schedule the watchdog work so
it gets removed in the watchdog thread context.Signed-off-by: Thomas Gleixner
LKML-Reference:
Cc: Martin Schwidefsky
Cc: John Stultz
15 Aug, 2009
6 commits
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update_wall_time calls change_clocksource HZ times per second to check
if a new clock source is available. In close to 100% of all calls
there is no new clock. Replace the tick based check by an update done
with stop_machine.Signed-off-by: Martin Schwidefsky
Cc: Ingo Molnar
Acked-by: John Stultz
Cc: Daniel Walker
LKML-Reference:
Signed-off-by: Thomas Gleixner -
The clocksource structure has two multipliers, the unmodified multiplier
clock->mult_orig and the NTP corrected multiplier clock->mult. The NTP
multiplier is misplaced in the struct clocksource, this is private
information of the timekeeping code. Add the mult field to the struct
timekeeper to contain the NTP corrected value, keep the unmodifed
multiplier in clock->mult and remove clock->mult_orig.Signed-off-by: Martin Schwidefsky
Cc: Ingo Molnar
Acked-by: John Stultz
Cc: Daniel Walker
LKML-Reference:
Signed-off-by: Thomas Gleixner -
Add struct timekeeper to keep the internal values timekeeping.c needs
in regard to the currently selected clock source. This moves the
timekeeping intervals, xtime_nsec and the ntp error value from struct
clocksource to struct timekeeper. The raw_time is removed from the
clocksource as well. It gets treated like xtime as a global variable.
Eventually xtime raw_time should be moved to struct timekeeper.[ tglx: minor cleanup ]
Signed-off-by: Martin Schwidefsky
Cc: Ingo Molnar
Acked-by: John Stultz
Cc: Daniel Walker
LKML-Reference:
Signed-off-by: Thomas Gleixner -
Move the downgrade of an unstable clocksource from the timer interrupt
context into the process context of a work queue thread. This is
needed to be able to do the clocksource switch with stop_machine.Signed-off-by: Martin Schwidefsky
Cc: Ingo Molnar
Acked-by: John Stultz
Cc: Daniel Walker
LKML-Reference:
Signed-off-by: Thomas Gleixner -
If a non high-resolution clocksource is first set as override clock
and then registered it becomes active even if the system is in one-shot
mode. Move the override check from sysfs_override_clocksource to the
clocksource selection. That fixes the bug and simplifies the code. The
check in clocksource_register for double registration of the same
clocksource is removed without replacement.To find the initial clocksource a new weak function in jiffies.c is
defined that returns the jiffies clocksource. The architecture code
can then override the weak function with a more suitable clocksource,
e.g. the TOD clock on s390.[ tglx: Folded in a fix from John Stultz ]
Signed-off-by: Martin Schwidefsky
Acked-by: John Stultz
Cc: Daniel Walker
LKML-Reference:
Signed-off-by: Thomas Gleixner -
The three inline functions clocksource_read, clocksource_enable and
clocksource_disable are simple wrappers of an indirect call plus the
copy from and to the mult_orig value. The functions are exclusively
used by the timekeeping code which has intimate knowledge of the
clocksource anyway. Therefore remove the inline functions. No
functional change.Signed-off-by: Martin Schwidefsky
Acked-by: John Stultz
Cc: Daniel Walker
LKML-Reference:
Signed-off-by: Thomas Gleixner
31 Jul, 2009
1 commit
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To fix the common case where ->enable() does not set up
mult, make sure mult_orig is saved in mult on disable.Also add comments to explain why we do this.
Signed-off-by: Magnus Damm
Cc: johnstul@us.ibm.com
Cc: lethal@linux-sh.org
Cc: akpm@linux-foundation.org
LKML-Reference:
Signed-off-by: Thomas Gleixner
02 May, 2009
1 commit
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Setup clocksource mult_orig in clocksource_enable().
Clocksource drivers can save power by using keeping the
device clock disabled while the clocksource is unused.In practice this means that the enable() and disable()
callbacks perform clk_enable() and clk_disable().The enable() callback may also use clk_get_rate() to get
the clock rate from the clock framework. This information
can then be used to calculate the shift and mult variables.Currently the mult_orig variable is setup from mult at
registration time only. This is conflicting with the above
case since the clock is disabled and the mult variable is
not yet calculated at the time of registration.Moving the mult_orig setup code to clocksource_enable()
allows us to both handle the common case with no enable()
callback and the mult-changed-after-enable() case.[ Impact: allow dynamic clock source usage ]
Signed-off-by: Magnus Damm
LKML-Reference:
Signed-off-by: Thomas Gleixner
22 Apr, 2009
2 commits
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Add enable() and disable() callbacks for clocksources.
This allows us to put unused clocksources in power save mode. The
functions clocksource_enable() and clocksource_disable() wrap the
callbacks and are inserted in the timekeeping code to enable before use
and disable after switching to a new clocksource.Signed-off-by: Magnus Damm
Acked-by: John Stultz
Cc: Thomas Gleixner
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Pass clocksource pointer to the read() callback for clocksources. This
allows us to share the callback between multiple instances.[hugh@veritas.com: fix powerpc build of clocksource pass clocksource mods]
[akpm@linux-foundation.org: cleanup]
Signed-off-by: Magnus Damm
Acked-by: John Stultz
Cc: Thomas Gleixner
Signed-off-by: Hugh Dickins
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
16 Feb, 2009
1 commit
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So far struct clocksource acted as the interface between time/timekeeping.c
and hardware. This patch generalizes the concept so that a similar
interface can also be used in other contexts. For that it introduces
new structures and related functions *without* touching the existing
struct clocksource.The reasons for adding these new structures to clocksource.[ch] are
* the APIs are clearly related
* struct clocksource could be cleaned up to use the new structs
* avoids proliferation of files with similar names (timesource.h?
timecounter.h?)As outlined in the discussion with John Stultz, this patch adds
* struct cyclecounter: stateless API to hardware which counts clock cycles
* struct timecounter: stateful utility code built on a cyclecounter which
provides a nanosecond counter
* only the function to read the nanosecond counter; deltas are used internally
and not exposed to users of timecounterThe code does no locking of the shared state. It must be called at least
as often as the cycle counter wraps around to detect these wrap arounds.
Both is the responsibility of the timecounter user.Acked-by: John Stultz
Signed-off-by: Patrick Ohly
Signed-off-by: David S. Miller
21 Aug, 2008
2 commits
-
In talking with Josip Loncaric, and his work on clock synchronization (see
btime.sf.net), he mentioned that for really close synchronization, it is
useful to have access to "hardware time", that is a notion of time that is
not in any way adjusted by the clock slewing done to keep close time sync.Part of the issue is if we are using the kernel's ntp adjusted
representation of time in order to measure how we should correct time, we
can run into what Paul McKenney aptly described as "Painting a road using
the lines we're painting as the guide".I had been thinking of a similar problem, and was trying to come up with a
way to give users access to a purely hardware based time representation
that avoided users having to know the underlying frequency and mask values
needed to deal with the wide variety of possible underlying hardware
counters.My solution is to introduce CLOCK_MONOTONIC_RAW. This exposes a
nanosecond based time value, that increments starting at bootup and has no
frequency adjustments made to it what so ever.The time is accessed from userspace via the posix_clock_gettime() syscall,
passing CLOCK_MONOTONIC_RAW as the clock_id.Signed-off-by: John Stultz
Signed-off-by: Roman Zippel
Signed-off-by: Andrew Morton
Signed-off-by: Ingo Molnar -
The clocksource frequency is represented by
clocksource->mult/2^(clocksource->shift). Currently, when NTP makes
adjustments to the clock frequency, they are made directly to the mult
value.This has the drawback that once changed, we cannot know what the orignal
mult value was, or how much adjustment has been applied.This property causes problems in calculating proper ntp intervals when
switching back and forth between clocksources.This patch separates the current mult value into a mult and mult_orig
pair. The mult_orig value stays constant, while the ntp clocksource
adjustments are done only to the mult value.This allows for correct ntp interval calculation and additionally lays the
groundwork for a new notion of time, what I'm calling the monotonic-raw
time, which is introduced in a following patch.Signed-off-by: John Stultz
Signed-off-by: Roman Zippel
Signed-off-by: Andrew Morton
Signed-off-by: Ingo Molnar
01 May, 2008
1 commit
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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
Cc: john stultz
Cc: Thomas Gleixner
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
18 Apr, 2008
1 commit
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In order to not trip the clocksource watchdog, kgdb must touch the
clocksource watchdog on the return to normal system run state.Signed-off-by: Jason Wessel
Signed-off-by: Ingo Molnar
30 Jan, 2008
2 commits
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On x86 the PIT might become an unusable clocksource. Add an unregister
function to provide a possibilty to remove the PIT from the list of
available clock sources.Signed-off-by: Thomas Gleixner
Signed-off-by: Ingo Molnar -
Signed-off-by: Atsushi Nemoto
Cc: john stultz
Signed-off-by: Andrew Morton
Signed-off-by: Ingo Molnar
Signed-off-by: Thomas Gleixner
19 Oct, 2007
1 commit
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On platforms that copy sys_tz into the vdso (currently only x86_64, soon to
include powerpc), it is possible for the vdso to get out of sync if a user
calls (admittedly unusual) settimeofday(NULL, ptr).This patch adds a hook for architectures that set
CONFIG_GENERIC_TIME_VSYSCALL to ensure when sys_tz is updated they can also
updatee their copy in the vdso.Signed-off-by: Tony Breeds
Cc: Andi Kleen
Cc: Tony Luck
Acked-by: John Stultz
Cc: Paul Mackerras
Cc: Benjamin Herrenschmidt
Cc: Thomas Gleixner
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
