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authorLinus Torvalds <torvalds@linux-foundation.org>2018-04-04 23:50:29 +0200
committerLinus Torvalds <torvalds@linux-foundation.org>2018-04-04 23:50:29 +0200
commit680014d6d1da84e9c7860831221ec74230721907 (patch)
treeb11afbabb939e65f841843842d1eebc63d41c240 /Documentation/trace
parentMerge tag 'random_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git... (diff)
parentalarmtimer: Init nanosleep alarm timer on stack (diff)
downloadlinux-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.rst22
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: