linux-toradex.git/kernel/trace/trace_sched_wakeup.c, branch v5.5

kernel/trace: Fix do not unregister tracepoints when register sched_migrate_task fail

2020-01-03T16:43:03+00:00

In the function, if register_trace_sched_migrate_task() returns error,
sched_switch/sched_wakeup_new/sched_wakeup won't unregister. That is
why fail_deprobe_sched_switch was added.

Link: http://lkml.kernel.org/r/20191231133530.2794-1-pilgrimtao@gmail.com

Cc: stable@vger.kernel.org
Fixes: 478142c39c8c2 ("tracing: do not grab lock in wakeup latency function tracing")
Signed-off-by: Kaitao Cheng 
Signed-off-by: Steven Rostedt (VMware)

sched/core: Convert get_task_struct() to return the task

2019-07-25T13:51:54+00:00

Returning the pointer that was passed in allows us to write
slightly more idiomatic code.  Convert a few users.

Signed-off-by: Matthew Wilcox (Oracle) 
Signed-off-by: Peter Zijlstra (Intel) 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Link: https://lkml.kernel.org/r/20190704221323.24290-1-willy@infradead.org
Signed-off-by: Ingo Molnar

tracing: Add conditional snapshot

2019-02-20T18:51:06+00:00

Currently, tracing snapshots are context-free - they capture the ring
buffer contents at the time the tracing_snapshot() function was
invoked, and nothing else.  Additionally, they're always taken
unconditionally - the calling code can decide whether or not to take a
snapshot, but the data used to make that decision is kept separately
from the snapshot itself.

This change adds the ability to associate with each trace instance
some user data, along with an 'update' function that can use that data
to determine whether or not to actually take a snapshot.  The update
function can then update that data along with any other state (as part
of the data presumably), if warranted.

Because snapshots are 'global' per-instance, only one user can enable
and use a conditional snapshot for any given trace instance.  To
enable a conditional snapshot (see details in the function and data
structure comments), the user calls tracing_snapshot_cond_enable().
Similarly, to disable a conditional snapshot and free it up for other
users, tracing_snapshot_cond_disable() should be called.

To actually initiate a conditional snapshot, tracing_snapshot_cond()
should be called.  tracing_snapshot_cond() will invoke the update()
callback, allowing the user to decide whether or not to actually take
the snapshot and update the user-defined data associated with the
snapshot.  If the callback returns 'true', tracing_snapshot_cond()
will then actually take the snapshot and return.

This scheme allows for flexibility in snapshot implementations - for
example, by implementing slightly different update() callbacks,
snapshots can be taken in situations where the user is only interested
in taking a snapshot when a new maximum in hit versus when a value
changes in any way at all.  Future patches will demonstrate both
cases.

Link: http://lkml.kernel.org/r/1bea07828d5fd6864a585f83b1eed47ce097eb45.1550100284.git.tom.zanussi@linux.intel.com

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

tracing: Show stacktrace for wakeup tracers

2019-02-06T16:56:19+00:00

This align the behavior of wakeup tracers with irqsoff latency tracer
that we record stacktrace at the beginning and end of waking up. The
stacktrace shows us what is happening in the kernel.

Link: http://lkml.kernel.org/r/20190116160249.7554-1-changbin.du@gmail.com

Signed-off-by: Changbin Du 
Signed-off-by: Steven Rostedt (VMware)

tracing: Show more info for funcgraph wakeup tracers

2019-02-06T16:56:19+00:00

Add these info fields to funcgraph wakeup tracers:
  o Show CPU info since the waker could be on a different CPU.
  o Show function duration and overhead.
  o Show IRQ markers.

Link: http://lkml.kernel.org/r/20190101154614.8887-3-changbin.du@gmail.com

Signed-off-by: Changbin Du 
Signed-off-by: Steven Rostedt (VMware)

function_graph: Support displaying relative timestamp

2019-02-06T16:56:18+00:00

When function_graph is used for latency tracers, relative timestamp
is more straightforward than absolute timestamp as function trace
does. This change adds relative timestamp support to function_graph
and applies to latency tracers (wakeup and irqsoff).

Instead of:

 # tracer: irqsoff
 #
 # irqsoff latency trace v1.1.5 on 5.0.0-rc1-test
 # --------------------------------------------------------------------
 # latency: 521 us, #1125/1125, CPU#2 | (M:preempt VP:0, KP:0, SP:0 HP:0 #P:8)
 #    -----------------
 #    | task: swapper/2-0 (uid:0 nice:0 policy:0 rt_prio:0)
 #    -----------------
 #  => started at: __schedule
 #  => ended at:   _raw_spin_unlock_irq
 #
 #
 #                                       _-----=> irqs-off
 #                                      / _----=> need-resched
 #                                     | / _---=> hardirq/softirq
 #                                     || / _--=> preempt-depth
 #                                     ||| /
 #     TIME        CPU  TASK/PID       ||||  DURATION                  FUNCTION CALLS
 #      |          |     |    |        ||||   |   |                     |   |   |   |
   124.974306 |   2)  systemd-693   |  d..1  0.000 us    |  __schedule();
   124.974307 |   2)  systemd-693   |  d..1              |    rcu_note_context_switch() {
   124.974308 |   2)  systemd-693   |  d..1  0.487 us    |      rcu_preempt_deferred_qs();
   124.974309 |   2)  systemd-693   |  d..1  0.451 us    |      rcu_qs();
   124.974310 |   2)  systemd-693   |  d..1  2.301 us    |    }
[..]
   124.974826 |   2)    -0    |  d..2              |  finish_task_switch() {
   124.974826 |   2)    -0    |  d..2              |    _raw_spin_unlock_irq() {
   124.974827 |   2)    -0    |  d..2  0.000 us    |  _raw_spin_unlock_irq();
   124.974828 |   2)    -0    |  d..2  0.000 us    |  tracer_hardirqs_on();
   -0       2d..2  552us : 
  => __schedule
  => schedule_idle
  => do_idle
  => cpu_startup_entry
  => start_secondary
  => secondary_startup_64

Show:

 # tracer: irqsoff
 #
 # irqsoff latency trace v1.1.5 on 5.0.0-rc1-test+
 # --------------------------------------------------------------------
 # latency: 511 us, #1053/1053, CPU#7 | (M:preempt VP:0, KP:0, SP:0 HP:0 #P:8)
 #    -----------------
 #    | task: swapper/7-0 (uid:0 nice:0 policy:0 rt_prio:0)
 #    -----------------
 #  => started at: __schedule
 #  => ended at:   _raw_spin_unlock_irq
 #
 #
 #                                       _-----=> irqs-off
 #                                      / _----=> need-resched
 #                                     | / _---=> hardirq/softirq
 #                                     || / _--=> preempt-depth
 #                                     ||| /
 #   REL TIME      CPU  TASK/PID       ||||  DURATION                  FUNCTION CALLS
 #      |          |     |    |        ||||   |   |                     |   |   |   |
         0 us |   7)   sshd-1704    |  d..1  0.000 us    |  __schedule();
         1 us |   7)   sshd-1704    |  d..1              |    rcu_note_context_switch() {
         1 us |   7)   sshd-1704    |  d..1  0.611 us    |      rcu_preempt_deferred_qs();
         2 us |   7)   sshd-1704    |  d..1  0.484 us    |      rcu_qs();
         3 us |   7)   sshd-1704    |  d..1  2.599 us    |    }
[..]
       509 us |   7)    -0    |  d..2              |  finish_task_switch() {
       510 us |   7)    -0    |  d..2              |    _raw_spin_unlock_irq() {
       510 us |   7)    -0    |  d..2  0.000 us    |  _raw_spin_unlock_irq();
       512 us |   7)    -0    |  d..2  0.000 us    |  tracer_hardirqs_on();
   -0       7d..2  543us : 
  => __schedule
  => schedule_idle
  => do_idle
  => cpu_startup_entry
  => start_secondary
  => secondary_startup_64

Link: http://lkml.kernel.org/r/20190101154614.8887-2-changbin.du@gmail.com

Signed-off-by: Changbin Du 
Signed-off-by: Steven Rostedt (VMware)

fgraph: Add new fgraph_ops structure to enable function graph hooks

2018-12-09T01:54:07+00:00

Currently the registering of function graph is to pass in a entry and return
function. We need to have a way to associate those functions together where
the entry can determine to run the return hook. Having a structure that
contains both functions will facilitate the process of converting the code
to be able to do such.

This is similar to the way function hooks are enabled (it passes in
ftrace_ops). Instead of passing in the functions to use, a single structure
is passed in to the registering function.

The unregister function is now passed in the fgraph_ops handle. When we
allow more than one callback to the function graph hooks, this will let the
system know which one to remove.

Reviewed-by: Joel Fernandes (Google) 
Signed-off-by: Steven Rostedt (VMware)

tracing: Rearrange functions in trace_sched_wakeup.c

2018-12-09T01:54:07+00:00

Rearrange the functions in trace_sched_wakeup.c so that there are fewer
 #ifdef CONFIG_FUNCTION_TRACER and #ifdef CONFIG_FUNCTION_GRAPH_TRACER,
instead of having the #ifdefs spread all over.

No functional change is made.

Signed-off-by: Steven Rostedt (VMware)

tracing/fgraph: Fix set_graph_function from showing interrupts

2018-11-30T03:09:00+00:00

The tracefs file set_graph_function is used to only function graph functions
that are listed in that file (or all functions if the file is empty). The
way this is implemented is that the function graph tracer looks at every
function, and if the current depth is zero and the function matches
something in the file then it will trace that function. When other functions
are called, the depth will be greater than zero (because the original
function will be at depth zero), and all functions will be traced where the
depth is greater than zero.

The issue is that when a function is first entered, and the handler that
checks this logic is called, the depth is set to zero. If an interrupt comes
in and a function in the interrupt handler is traced, its depth will be
greater than zero and it will automatically be traced, even if the original
function was not. But because the logic only looks at depth it may trace
interrupts when it should not be.

The recent design change of the function graph tracer to fix other bugs
caused the depth to be zero while the function graph callback handler is
being called for a longer time, widening the race of this happening. This
bug was actually there for a longer time, but because the race window was so
small it seldom happened. The Fixes tag below is for the commit that widen
the race window, because that commit belongs to a series that will also help
fix the original bug.

Cc: stable@kernel.org
Fixes: 39eb456dacb5 ("function_graph: Use new curr_ret_depth to manage depth instead of curr_ret_stack")
Reported-by: Joe Lawrence 
Tested-by: Joe Lawrence 
Signed-off-by: Steven Rostedt (VMware)

Merge branch 'linus' into sched/core, to pick up fixes

2017-11-08T09:17:15+00:00

Signed-off-by: Ingo Molnar