linux-toradex.git/include/linux/time.h, branch tegra-10.9.9

nohz: Prevent clocksource wrapping during idle

2010-01-28T23:01:12+00:00

commit 98962465ed9e6ea99c38e0af63fe1dcb5a79dc25 upstream.

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: <1250617512-23567-2-git-send-email-jon-hunter@ti.com>
Signed-off-by: Thomas Gleixner 
Signed-off-by: Greg Kroah-Hartman

time: add function to convert between calendar time and broken-down time for universal use

2009-09-24T14:20:56+00:00

There are many similar code in kernel for one object: convert time between
calendar time and broken-down time.

Here is some source I found:
  fs/ncpfs/dir.c
  fs/smbfs/proc.c
  fs/fat/misc.c
  fs/udf/udftime.c
  fs/cifs/netmisc.c
  net/netfilter/xt_time.c
  drivers/scsi/ips.c
  drivers/input/misc/hp_sdc_rtc.c
  drivers/rtc/rtc-lib.c
  arch/ia64/hp/sim/boot/fw-emu.c
  arch/m68k/mac/misc.c
  arch/powerpc/kernel/time.c
  arch/parisc/include/asm/rtc.h
  ...

We can make a common function for this type of conversion, At least we
can get following benefit:

1: Make kernel simple and unify
2: Easy to fix bug in converting code
3: Reduce clone of code in future
   For example, I'm trying to make ftrace display walltime,
   this patch will make me easy.

This code is based on code from glibc-2.6

Signed-off-by: Zhao Lei 
Cc: OGAWA Hirofumi 
Cc: Thomas Gleixner 
Cc: Ingo Molnar 
Cc: Pavel Machek 
Cc: Andi Kleen 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

time: Prevent 32 bit overflow with set_normalized_timespec()

2009-09-15T08:17:30+00:00

set_normalized_timespec() nsec argument is of type long. The recent
timekeeping changes of ktime_get_ts() feed 

	ts->tv_nsec + tomono.tv_nsec + nsecs

to set_normalized_timespec(). On 32 bit machines that sum can be
larger than (1 << 31) and therefor result in a negative value which
screws up the result completely.

Make the nsec argument of set_normalized_timespec() s64 to fix the
problem at hand. This also prevents similar problems for future users
of set_normalized_timespec().

Signed-off-by: Thomas Gleixner 
Tested-by: Carsten Emde 
LKML-Reference: 
Cc: Martin Schwidefsky 
Cc: John Stultz

time: Introduce CLOCK_REALTIME_COARSE

2009-08-21T19:43:46+00:00

After talking with some application writers who want very fast, but not
fine-grained timestamps, I decided to try to implement new clock_ids
to clock_gettime(): CLOCK_REALTIME_COARSE and CLOCK_MONOTONIC_COARSE
which returns the time at the last tick. This is very fast as we don't
have to access any hardware (which can be very painful if you're using
something like the acpi_pm clocksource), and we can even use the vdso
clock_gettime() method to avoid the syscall. The only trade off is you
only get low-res tick grained time resolution.

This isn't a new idea, I know Ingo has a patch in the -rt tree that made
the vsyscall gettimeofday() return coarse grained time when the
vsyscall64 sysctrl was set to 2. However this affects all applications
on a system.

With this method, applications can choose the proper speed/granularity
trade-off for themselves.

Signed-off-by: John Stultz 
Cc: Andi Kleen 
Cc: nikolag@ca.ibm.com
Cc: Darren Hart 
Cc: arjan@infradead.org
Cc: jonathan@jonmasters.org
LKML-Reference: <1250734414.6897.5.camel@localhost.localdomain>
Signed-off-by: Thomas Gleixner

timekeeping: Introduce read_boot_clock

2009-08-15T08:55:47+00:00

Add the new function read_boot_clock to get the exact time the system
has been started. For architectures without support for exact boot
time a new weak function is added that returns 0.  Use the exact boot
time to initialize wall_to_monotonic, or xtime if the read_boot_clock
returned 0.

Signed-off-by: Martin Schwidefsky 
Cc: Ingo Molnar 
Acked-by: John Stultz 
Cc: Daniel Walker 
LKML-Reference: <20090814134811.296703241@de.ibm.com>
Signed-off-by: Thomas Gleixner

timekeeping: Increase granularity of read_persistent_clock()

2009-08-15T08:55:46+00:00

The persistent clock of some architectures (e.g. s390) have a
better granularity than seconds. To reduce the delta between the
host clock and the guest clock in a virtualized system change the 
read_persistent_clock function to return a struct timespec.

Signed-off-by: Martin Schwidefsky 
Cc: Ingo Molnar 
Acked-by: John Stultz 
Cc: Daniel Walker 
LKML-Reference: <20090814134811.013873340@de.ibm.com>
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

timekeeping: create arch_gettimeoffset infrastructure

2009-05-02T09:45:15+00:00

Some arches don't supply their own clocksource. This is mainly the
case in architectures that get their inter-tick times by reading the
counter on their interval timer.  Since these timers wrap every tick,
they're not really useful as clocksources.  Wrapping them to act like
one is possible but not very efficient. So we provide a callout these
arches can implement for use with the jiffies clocksource to provide
finer then tick granular time.

[ Impact: ease the migration to generic time keeping ]

Signed-off-by: John Stultz 
Signed-off-by: Andrew Morton 
Signed-off-by: Thomas Gleixner

make exported headers use strict posix types

2009-03-26T17:14:14+00:00

A number of standard posix types are used in exported headers, which
is not allowed if __STRICT_KERNEL_NAMES is defined. In order to
get rid of the non-__STRICT_KERNEL_NAMES part and to make sane headers
the default, we have to change them all to safe types.

There are also still some leftovers in reiserfs_fs.h, elfcore.h
and coda.h, but these files have not compiled in user space for
a long time.

This leaves out the various integer types ({u_,u,}int{8,16,32,64}_t),
which we take care of separately.

Signed-off-by: Arnd Bergmann 
Acked-by: Mauro Carvalho Chehab 
Cc: David Airlie 
Cc: Arnaldo Carvalho de Melo 
Cc: YOSHIFUJI Hideaki 
Cc: netdev@vger.kernel.org
Cc: linux-ppp@vger.kernel.org
Cc: Jaroslav Kysela 
Cc: Takashi Iwai 
Cc: David Woodhouse 
Signed-off-by: H. Peter Anvin 
Signed-off-by: Ingo Molnar

sched_clock: prevent scd->clock from moving backwards, take #2

2008-12-31T08:53:21+00:00

Redo:

  5b7dba4: sched_clock: prevent scd->clock from moving backwards

which had to be reverted due to s2ram hangs:

  ca7e716: Revert "sched_clock: prevent scd->clock from moving backwards"

... this time with resume restoring GTOD later in the sequence
taken into account as well.

The "timekeeping_suspended" flag is not very nice but we cannot call into
GTOD before it has been properly resumed and the scheduler will run very
early in the resume sequence.

Cc: 
Signed-off-by: Ingo Molnar