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menu "LITMUS^RT"
menu "Scheduling"
config PLUGIN_CEDF
bool "Clustered-EDF"
depends on X86 && SYSFS
default y
help
Include the Clustered EDF (C-EDF) plugin in the kernel.
This is appropriate for large platforms with shared caches.
On smaller platforms (e.g., ARM PB11MPCore), using C-EDF
makes little sense since there aren't any shared caches.
config PLUGIN_PFAIR
bool "PFAIR"
depends on HIGH_RES_TIMERS && !NO_HZ
default y
help
Include the PFAIR plugin (i.e., the PD^2 scheduler) in the kernel.
The PFAIR plugin requires high resolution timers (for staggered quanta)
and does not support NO_HZ (quanta could be missed when the system is idle).
If unsure, say Yes.
config MERGE_TIMERS
bool "Timer-merging Support"
depends on HIGH_RES_TIMERS
default y
help
Include support for merging timers.
config MERGE_TIMERS_WINDOW
int "Timer-merging Window (in nanoseconds)"
depends on MERGE_TIMERS
default 1000
help
Window within which seperate timers may be merged.
config RELEASE_MASTER
bool "Release-master Support"
depends on ARCH_HAS_SEND_PULL_TIMERS
default n
help
In GSN-EDF, allow one processor to act as a dedicated interrupt
processor that services all timer interrupts, but that does not schedule
real-time tasks. See RTSS'09 paper for details
(http://www.cs.unc.edu/~anderson/papers.html).
menu "Mixed Criticality"
config PLUGIN_MC
bool "Mixed Criticality Scheduler"
depends on X86 && SYSFS
default y
help
Include the mixed criticality scheduler. This plugin depends
on the global release-master processor for its _REDIRECT and
_RELEASE_MASTER options.
If unsure, say Yes.
config PLUGIN_MC_LEVEL_A_MAX_TASKS
int "Maximum level A tasks"
depends on PLUGIN_MC
range 1 128
default 32
help
The maximum number of level A tasks allowed (per-cpu) in level A.
config PLUGIN_MC_RELEASE_MASTER
bool "Release-master support for MC"
depends on PLUGIN_MC && RELEASE_MASTER
default y
help
Send all timer interrupts to the system-wide release-master CPU.
config PLUGIN_MC_REDIRECT
bool "Redirect Work to Release-master"
depends on PLUGIN_MC && RELEASE_MASTER
default y
help
Allow processors to send work involving global state to the
release-master cpu in order to avoid excess overheads during
partitioned decisions.
config FTRACE_CPU
int "CPU for Tracing"
depends on PLUGIN_MC
default -1
help
Keep one CPU free for the tasks which trace and flush
scheduling and overhead data.
endmenu
endmenu
menu "Real-Time Synchronization"
config NP_SECTION
bool "Non-preemptive section support"
default n
help
Allow tasks to become non-preemptable.
Note that plugins still need to explicitly support non-preemptivity.
Currently, only GSN-EDF and PSN-EDF have such support.
This is required to support locking protocols such as the FMLP.
If disabled, all tasks will be considered preemptable at all times.
config LITMUS_LOCKING
bool "Support for real-time locking protocols"
depends on NP_SECTION
default n
help
Enable LITMUS^RT's deterministic multiprocessor real-time
locking protocols.
Say Yes if you want to include locking protocols such as the FMLP and
Baker's SRP.
endmenu
menu "Tracing"
config FEATHER_TRACE
bool "Feather-Trace Infrastructure"
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_TASK_TRACE
bool "Trace real-time tasks"
depends on FEATHER_TRACE
default y
help
Include support for the sched_trace_XXX() tracing functions. This
allows the collection of real-time task events such as job
completions, job releases, early completions, etc. This results in a
small overhead in the scheduling code. Disable if the overhead is not
acceptable (e.g., benchmarking).
Say Yes for debugging.
Say No for overhead tracing.
config SCHED_TASK_TRACE_SHIFT
int "Buffer size for sched_trace_xxx() events"
depends on SCHED_TASK_TRACE
range 8 13
default 9
help
Select the buffer size of sched_trace_xxx() events as a power of two.
These buffers are statically allocated as per-CPU data. Each event
requires 24 bytes storage plus one additional flag byte. Too large
buffers can cause issues with the per-cpu allocator (and waste
memory). Too small buffers can cause scheduling events to be lost. The
"right" size is workload dependent and depends on the number of tasks,
each task's period, each task's number of suspensions, and how often
the buffer is flushed.
Examples: 12 => 4k events
10 => 1k events
8 => 512 events
config SCHED_OVERHEAD_TRACE
bool "Record timestamps for overhead measurements"
depends on FEATHER_TRACE
default n
help
Export event stream for overhead tracing.
Say Yes for overhead tracing.
config SCHED_DEBUG_TRACE
bool "TRACE() debugging"
default y
help
Include support for sched_trace_log_messageg(), which is used to
implement TRACE(). If disabled, no TRACE() messages will be included
in the kernel, and no overheads due to debugging statements will be
incurred by the scheduler. Disable if the overhead is not acceptable
(e.g. benchmarking).
Say Yes for debugging.
Say No for overhead tracing.
config SCHED_DEBUG_TRACE_SHIFT
int "Buffer size for TRACE() buffer"
depends on SCHED_DEBUG_TRACE
range 14 22
default 18
help
Select the amount of memory needed per for the TRACE() buffer, as a
power of two. The TRACE() buffer is global and statically allocated. If
the buffer is too small, there will be holes in the TRACE() log if the
buffer-flushing task is starved.
The default should be sufficient for most systems. Increase the buffer
size if the log contains holes. Reduce the buffer size when running on
a memory-constrained system.
Examples: 14 => 16KB
18 => 256KB
20 => 1MB
This buffer is exported to usespace using a misc device as
'litmus/log'. On a system with default udev rules, a corresponding
character device node should be created at /dev/litmus/log. The buffer
can be flushed using cat, e.g., 'cat /dev/litmus/log > my_log_file.txt'.
config SCHED_DEBUG_TRACE_CALLER
bool "Include [function@file:line] tag in TRACE() log"
depends on SCHED_DEBUG_TRACE
default n
help
With this option enabled, TRACE() prepends
"[<function name>@<filename>:<line number>]"
to each message in the debug log. Enable this to aid in figuring out
what was called in which order. The downside is that it adds a lot of
clutter.
If unsure, say No.
endmenu
endmenu
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