linux-stable.git/Documentation/trace, branch v4.17.2

Revert: Unify CLOCK_MONOTONIC and CLOCK_BOOTTIME

2018-04-26T12:53:32+00:00

Revert commits

92af4dcb4e1c ("tracing: Unify the "boot" and "mono" tracing clocks")
127bfa5f4342 ("hrtimer: Unify MONOTONIC and BOOTTIME clock behavior")
7250a4047aa6 ("posix-timers: Unify MONOTONIC and BOOTTIME clock behavior")
d6c7270e913d ("timekeeping: Remove boot time specific code")
f2d6fdbfd238 ("Input: Evdev - unify MONOTONIC and BOOTTIME clock behavior")
d6ed449afdb3 ("timekeeping: Make the MONOTONIC clock behave like the BOOTTIME clock")
72199320d49d ("timekeeping: Add the new CLOCK_MONOTONIC_ACTIVE clock")

As stated in the pull request for the unification of CLOCK_MONOTONIC and
CLOCK_BOOTTIME, it was clear that we might have to revert the change.

As reported by several folks systemd and other applications rely on the
documented behaviour of CLOCK_MONOTONIC on Linux and break with the above
changes. After resume daemons time out and other timeout related issues are
observed. Rafael compiled this list:

* systemd kills daemons on resume, after >WatchdogSec seconds
  of suspending (Genki Sky).  [Verified that that's because systemd uses
  CLOCK_MONOTONIC and expects it to not include the suspend time.]

* systemd-journald misbehaves after resume:
  systemd-journald[7266]: File /var/log/journal/016627c3c4784cd4812d4b7e96a34226/system.journal
corrupted or uncleanly shut down, renaming and replacing.
  (Mike Galbraith).

* NetworkManager reports "networking disabled" and networking is broken
  after resume 50% of the time (Pavel).  [May be because of systemd.]

* MATE desktop dims the display and starts the screensaver right after
  system resume (Pavel).

* Full system hang during resume (me).  [May be due to systemd or NM or both.]

That happens on debian and open suse systems.

It's sad, that these problems were neither catched in -next nor by those
folks who expressed interest in this change.

Reported-by: Rafael J. Wysocki 
Reported-by: Genki Sky ,
Reported-by: Pavel Machek 
Signed-off-by: Thomas Gleixner 
Cc: Dmitry Torokhov 
Cc: John Stultz 
Cc: Jonathan Corbet 
Cc: Kevin Easton 
Cc: Linus Torvalds 
Cc: Mark Salyzyn 
Cc: Michael Kerrisk 
Cc: Peter Zijlstra 
Cc: Petr Mladek 
Cc: Prarit Bhargava 
Cc: Sergey Senozhatsky 
Cc: Steven Rostedt

Merge tag 'trace-v4.17' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

2018-04-10T18:27:30+00:00

Pull tracing updates from Steven Rostedt:
 "New features:

   - Tom Zanussi's extended histogram work.

     This adds the synthetic events to have histograms from multiple
     event data Adds triggers "onmatch" and "onmax" to call the
     synthetic events Several updates to the histogram code from this

   - Allow way to nest ring buffer calls in the same context

   - Allow absolute time stamps in ring buffer

   - Rewrite of filter code parsing based on Al Viro's suggestions

   - Setting of trace_clock to global if TSC is unstable (on boot)

   - Better OOM handling when allocating large ring buffers

   - Added initcall tracepoints (consolidated initcall_debug code with
     them)

  And other various fixes and clean ups"

* tag 'trace-v4.17' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (68 commits)
  init: Have initcall_debug still work without CONFIG_TRACEPOINTS
  init, tracing: Have printk come through the trace events for initcall_debug
  init, tracing: instrument security and console initcall trace events
  init, tracing: Add initcall trace events
  tracing: Add rcu dereference annotation for test func that touches filter->prog
  tracing: Add rcu dereference annotation for filter->prog
  tracing: Fixup logic inversion on setting trace_global_clock defaults
  tracing: Hide global trace clock from lockdep
  ring-buffer: Add set/clear_current_oom_origin() during allocations
  ring-buffer: Check if memory is available before allocation
  lockdep: Add print_irqtrace_events() to __warn
  vsprintf: Do not preprocess non-dereferenced pointers for bprintf (%px and %pK)
  tracing: Uninitialized variable in create_tracing_map_fields()
  tracing: Make sure variable string fields are NULL-terminated
  tracing: Add action comparisons when testing matching hist triggers
  tracing: Don't add flag strings when displaying variable references
  tracing: Fix display of hist trigger expressions containing timestamps
  ftrace: Drop a VLA in module_exists()
  tracing: Mention trace_clock=global when warning about unstable clocks
  tracing: Default to using trace_global_clock if sched_clock is unstable
  ...

mm, page_alloc: wakeup kcompactd even if kswapd cannot free more memory

2018-04-06T04:36:27+00:00

Kswapd will not wakeup if per-zone watermarks are not failing or if too
many previous attempts at background reclaim have failed.

This can be true if there is a lot of free memory available.  For high-
order allocations, kswapd is responsible for waking up kcompactd for
background compaction.  If the zone is not below its watermarks or
reclaim has recently failed (lots of free memory, nothing left to
reclaim), kcompactd does not get woken up.

When __GFP_DIRECT_RECLAIM is not allowed, allow kcompactd to still be
woken up even if kswapd will not reclaim.  This allows high-order
allocations, such as thp, to still trigger background compaction even
when the zone has an abundance of free memory.

Link: http://lkml.kernel.org/r/alpine.DEB.2.20.1803111659420.209721@chino.kir.corp.google.com
Signed-off-by: David Rientjes 
Acked-by: Vlastimil Babka 
Cc: Mel Gorman 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Merge branch 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2018-04-04T21:50:29+00:00

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

Merge tag 'docs-4.17' of git://git.lwn.net/linux

2018-04-03T20:35:51+00:00

Pull documentation updates from Jonathan Corbet:
 "There's been a fair amount of activity in Documentation/ this time
  around:

   - Lots of work aligning Documentation/ABI with reality, done by
     Aishwarya Pant.

   - The trace documentation has been converted to RST by Changbin Du

   - I thrashed up kernel-doc to deal with a parsing issue and to try to
     make the code more readable. It's still a 20+-year-old Perl hack,
     though.

   - Lots of other updates, typo fixes, and more"

* tag 'docs-4.17' of git://git.lwn.net/linux: (82 commits)
  Documentation/process: update FUSE project website
  docs: kernel-doc: fix parsing of arrays
  dmaengine: Fix spelling for parenthesis in dmatest documentation
  dmaengine: Make dmatest.rst indeed reST compatible
  dmaengine: Add note to dmatest documentation about supported channels
  Documentation: magic-numbers: Fix typo
  Documentation: admin-guide: add kvmconfig, xenconfig and tinyconfig commands
  Input: alps - Update documentation for trackstick v3 format
  Documentation: Mention why %p prints ptrval
  COPYING: use the new text with points to the license files
  COPYING: create a new file with points to the Kernel license files
  Input: trackpoint: document sysfs interface
  xfs: Change URL for the project in xfs.txt
  char/bsr: add sysfs interface documentation
  acpi: nfit: document sysfs interface
  block: rbd: update sysfs interface
  Documentation/sparse: fix typo
  Documentation/CodingStyle: Add an example for braces
  docs/vm: update 00-INDEX
  kernel-doc: Remove __sched markings
  ...

tracing: Unify the "boot" and "mono" tracing clocks

2018-03-13T06:34:23+00:00

Unify the "boot" and "mono" tracing clocks and document the new behaviour.

Signed-off-by: Thomas Gleixner 
Cc: Dmitry Torokhov 
Cc: John Stultz 
Cc: Jonathan Corbet 
Cc: Kevin Easton 
Cc: Linus Torvalds 
Cc: Mark Salyzyn 
Cc: Michael Kerrisk 
Cc: Peter Zijlstra 
Cc: Petr Mladek 
Cc: Prarit Bhargava 
Cc: Sergey Senozhatsky 
Cc: Steven Rostedt 
Link: http://lkml.kernel.org/r/20180301165150.489635255@linutronix.de
Signed-off-by: Ingo Molnar

tracing: Add a clock attribute for hist triggers

2018-03-10T21:06:03+00:00

The default clock if timestamps are used in a histogram is "global".
If timestamps aren't used, the clock is irrelevant.

Use the "clock=" param only if you want to override the default
"global" clock for a histogram with timestamps.

Link: http://lkml.kernel.org/r/427bed1389c5d22aa40c3e0683e30cc3d151e260.1516069914.git.tom.zanussi@linux.intel.com

Signed-off-by: Tom Zanussi 
Signed-off-by: Rajvi Jingar 
Signed-off-by: Steven Rostedt (VMware)

tracing: Add inter-event hist trigger Documentation

2018-03-10T21:06:02+00:00

Add background and details on inter-event hist triggers, including
hist variables, synthetic events, and actions.

Link: http://lkml.kernel.org/r/b0414efb66535aa52aa7411f58c3d56724027fce.1516069914.git.tom.zanussi@linux.intel.com

Signed-off-by: Tom Zanussi 
Signed-off-by: Baohong Liu 
Signed-off-by: Steven Rostedt (VMware)

tracing: Add 'last error' error facility for hist triggers

2018-03-10T21:06:02+00:00

With the addition of variables and actions, it's become necessary to
provide more detailed error information to users about syntax errors.

Add a 'last error' facility accessible via the erroring event's 'hist'
file.  Reading the hist file after an error will display more detailed
information about what went wrong, if information is available.  This
extended error information will be available until the next hist
trigger command for that event.

  # echo xxx > /sys/kernel/debug/tracing/events/sched/sched_wakeup/trigger
  echo: write error: Invalid argument

  # cat /sys/kernel/debug/tracing/events/sched/sched_wakeup/hist

  ERROR: Couldn't yyy: zzz
  Last command: xxx

Also add specific error messages for variable and action errors.

Link: http://lkml.kernel.org/r/64e9c422fc8aeafcc2f7a3b4328c0cffe7969129.1516069914.git.tom.zanussi@linux.intel.com

Signed-off-by: Tom Zanussi 
Signed-off-by: Steven Rostedt (VMware)

tracing: Add cpu field for hist triggers

2018-03-10T21:06:01+00:00

A common key to use in a histogram is the cpuid - add a new cpu
'synthetic' field named 'cpu' for that purpose.

Link: http://lkml.kernel.org/r/89537645bfc957e0d76e2cacf5f0ada88691a6cc.1516069914.git.tom.zanussi@linux.intel.com

Signed-off-by: Tom Zanussi 
Signed-off-by: Steven Rostedt (VMware)