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menu "LITMUS^RT"
menu "Tracing"
config FEATHER_TRACE
bool "Feather-Trace Infrastructure"
depends on !RELOCATABLE
default y
help
Feather-Trace basic tracing infrastructure. Includes device file
driver and instrumentation point support.
There are actually two implementations of Feather-Trace.
1) A slower, but portable, default implementation.
2) Architecture-specific implementations that rewrite kernel .text at runtime.
If enabled, Feather-Trace will be based on 2) if available (currently only for x86).
However, if DEBUG_RODATA=y, then Feather-Trace will choose option 1) in any case
to avoid problems with write-protected .text pages.
Bottom line: to avoid increased overheads, choose DEBUG_RODATA=n.
Note that this option only enables the basic Feather-Trace infrastructure;
you still need to enable SCHED_TASK_TRACE and/or SCHED_OVERHEAD_TRACE to
actually enable any events.
config SCHED_OVERHEAD_TRACE
bool "Record timestamps for overhead measurements"
depends on FEATHER_TRACE
default y
help
Export event stream for overhead tracing.
Say Yes for overhead tracing.
config SCHED_OVERHEAD_TRACE_SHIFT
int "Buffer size for Feather-Trace overhead data"
depends on SCHED_OVERHEAD_TRACE
range 15 32
default 22
help
Select the buffer size for the Feather-Trace overhead tracing
infrastructure (/dev/litmus/ft_trace0 & ftcat) as a power of two. The
larger the buffer, the less likely the chance of buffer overflows if
the ftcat process is starved by real-time activity. In machines with
large memories, large buffer sizes are recommended.
Examples: 16 => 2 MB
24 => 512 MB
26 => 2G MB
endmenu
endmenu
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