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author | Linus Torvalds <torvalds@linux-foundation.org> | 2018-04-04 23:50:29 +0200 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2018-04-04 23:50:29 +0200 |
commit | 680014d6d1da84e9c7860831221ec74230721907 (patch) | |
tree | b11afbabb939e65f841843842d1eebc63d41c240 /Documentation/trace | |
parent | Merge tag 'random_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git... (diff) | |
parent | alarmtimer: Init nanosleep alarm timer on stack (diff) | |
download | linux-680014d6d1da84e9c7860831221ec74230721907.tar.xz linux-680014d6d1da84e9c7860831221ec74230721907.zip |
Merge branch 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull time(r) updates from Thomas Gleixner:
"A small set of updates for timers and timekeeping:
- The most interesting change is the consolidation of clock MONOTONIC
and clock BOOTTIME.
Clock MONOTONIC behaves now exactly like clock BOOTTIME and does
not longer ignore the time spent in suspend. A new clock
MONOTONIC_ACTIVE is provived which behaves like clock MONOTONIC in
kernels before this change. This allows applications to
programmatically check for the clock MONOTONIC behaviour.
As discussed in the review thread, this has the potential of
breaking user space and we might have to revert this. Knock on wood
that we can avoid that exercise.
- Updates to the NTP mechanism to improve accuracy
- A new kernel internal data structure to aid the ongoing Y2038 work.
- Cleanups and simplifications of the clocksource code.
- Make the alarmtimer code play nicely with debugobjects"
* 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
alarmtimer: Init nanosleep alarm timer on stack
y2038: Introduce struct __kernel_old_timeval
tracing: Unify the "boot" and "mono" tracing clocks
hrtimer: Unify MONOTONIC and BOOTTIME clock behavior
posix-timers: Unify MONOTONIC and BOOTTIME clock behavior
timekeeping: Remove boot time specific code
Input: Evdev - unify MONOTONIC and BOOTTIME clock behavior
timekeeping: Make the MONOTONIC clock behave like the BOOTTIME clock
timekeeping: Add the new CLOCK_MONOTONIC_ACTIVE clock
timekeeping/ntp: Determine the multiplier directly from NTP tick length
timekeeping/ntp: Don't align NTP frequency adjustments to ticks
clocksource: Use ATTRIBUTE_GROUPS
clocksource: Use DEVICE_ATTR_RW/RO/WO to define device attributes
clocksource: Don't walk the clocksource list for empty override
Diffstat (limited to 'Documentation/trace')
-rw-r--r-- | Documentation/trace/ftrace.rst | 22 |
1 files changed, 7 insertions, 15 deletions
diff --git a/Documentation/trace/ftrace.rst b/Documentation/trace/ftrace.rst index 0bc33ad4a3f9..fdf5fb54a04c 100644 --- a/Documentation/trace/ftrace.rst +++ b/Documentation/trace/ftrace.rst @@ -461,21 +461,13 @@ of ftrace. Here is a list of some of the key files: and ticks at the same rate as the hardware clocksource. boot: - This is the boot clock (CLOCK_BOOTTIME) and is based on the - fast monotonic clock, but also accounts for time spent in - suspend. Since the clock access is designed for use in - tracing in the suspend path, some side effects are possible - if clock is accessed after the suspend time is accounted before - the fast mono clock is updated. In this case, the clock update - appears to happen slightly sooner than it normally would have. - Also on 32-bit systems, it's possible that the 64-bit boot offset - sees a partial update. These effects are rare and post - processing should be able to handle them. See comments in the - ktime_get_boot_fast_ns() function for more information. - - To set a clock, simply echo the clock name into this file:: - - echo global > trace_clock + Same as mono. Used to be a separate clock which accounted + for the time spent in suspend while CLOCK_MONOTONIC did + not. + + To set a clock, simply echo the clock name into this file:: + + # echo global > trace_clock trace_marker: |