a task is woken to the task is actually scheduled in.
One of the most common uses of ftrace is the event tracing.
-Throughout the kernel is hundreds of static event points that
+Throughout the kernel are hundreds of static event points that
can be enabled via the tracefs file system to see what is
going on in certain parts of the kernel.
not be listed in this count.
If the callback registered to be traced by a function with
- the "save regs" attribute (thus even more overhead), a 'R'
+ the "save regs" attribute (thus even more overhead), an 'R'
will be displayed on the same line as the function that
is returning registers.
an 'I' will be displayed on the same line as the function that
can be overridden.
- If a non ftrace trampoline is attached (BPF) a 'D' will be displayed.
+ If a non-ftrace trampoline is attached (BPF) a 'D' will be displayed.
Note, normal ftrace trampolines can also be attached, but only one
"direct" trampoline can be attached to a given function at a time.
If a function had either the "ip modify" or a "direct" call attached to
it in the past, a 'M' will be shown. This flag is never cleared. It is
- used to know if a function was every modified by the ftrace infrastructure,
+ used to know if a function was ever modified by the ftrace infrastructure,
and can be used for debugging.
If the architecture supports it, it will also show what callback
This file contains all the functions that ever had a function callback
to it via the ftrace infrastructure. It has the same format as
- enabled_functions but shows all functions that have every been
+ enabled_functions but shows all functions that have ever been
traced.
To see any function that has every been modified by "ip modify" or a
Whenever an event is recorded into the ring buffer, a
"timestamp" is added. This stamp comes from a specified
clock. By default, ftrace uses the "local" clock. This
- clock is very fast and strictly per cpu, but on some
+ clock is very fast and strictly per CPU, but on some
systems it may not be monotonic with respect to other
CPUs. In other words, the local clocks may not be in sync
with local clocks on other CPUs.
"mmiotrace"
- A special tracer that is used to trace binary module.
+ A special tracer that is used to trace binary modules.
It will trace all the calls that a module makes to the
hardware. Everything it writes and reads from the I/O
as well.
The compound key examples used a key and a sum value (hitcount) to
sort the output, but we can just as easily use two keys instead.
- Here's an example where we use a compound key composed of the the
+ Here's an example where we use a compound key composed of the
common_pid and size event fields. Sorting with pid as the primary
key and 'size' as the secondary key allows us to display an
ordered summary of the recvfrom sizes, with counts, received by