path: root/litmus/Kconfig

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 RELEASE_MASTER
        bool "Release-master Support"
	depends on ARCH_HAS_SEND_PULL_TIMERS
	default n
	help
           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).
           Currently only supported by GSN-EDF.

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 "Performance Enhancements"

config SCHED_CPU_AFFINITY
	bool "Local Migration Affinity"
	depends on X86
	default y
	help
	  Rescheduled tasks prefer CPUs near to their previously used CPU.  This
	  may improve performance through possible preservation of cache affinity.

	  Warning: May make bugs harder to find since tasks may migrate less often.

	  NOTES:
	  	* Feature is not utilized by PFair/PD^2.

	  Say Yes if unsure.

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.

config PREEMPT_STATE_TRACE
       bool "Trace preemption state machine transitions"
       depends on SCHED_DEBUG_TRACE
       default n
       help
         With this option enabled, each CPU will log when it transitions
	 states in the preemption state machine. This state machine is
	 used to determine how to react to IPIs (avoid races with in-flight IPIs).

	 Warning: this creates a lot of information in the debug trace. Only
	 recommended when you are debugging preemption-related races.

	 If unsure, say No.

endmenu

menu "Interrupt Handling"

config LITMUS_THREAD_ALL_SOFTIRQ
       bool "Process all softirqs in ksoftirqd threads."
       default n
       help
	     (Experimental) Thread all softirqs to ksoftirqd
		 daemon threads, similar to PREEMPT_RT.  I/O
		 throughput will will drop with this enabled, but
		 latencies due to interrupts will be reduced.

		 WARNING: Timer responsiveness will likely be
		 decreased as timer callbacks are also threaded.
		 This is unlike PREEEMPT_RTs hardirqs.

		If unsure, say No.


choice 
	prompt "Scheduling of interrupt bottom-halves in Litmus."
	default LITMUS_SOFTIRQD_NONE
	depends on LITMUS_LOCKING && !LITMUS_THREAD_ALL_SOFTIRQ
	help
		Schedule tasklets with known priorities in Litmus.

config LITMUS_SOFTIRQD_NONE
	bool "No tasklet scheduling in Litmus."
	help
	  Don't schedule tasklets in Litmus.  Default.

config LITMUS_SOFTIRQD
	bool "Spawn klitirqd interrupt handling threads."
	help
	  Create klitirqd interrupt handling threads.  Work must be
	  specifically dispatched to these workers.  (Softirqs for
	  Litmus tasks are not magically redirected to klitirqd.)

	  G-EDF/RM, C-EDF/RM ONLY for now!


config LITMUS_PAI_SOFTIRQD
	bool "Defer tasklets to context switch points."
	help
	  Only execute scheduled tasklet bottom halves at
	  scheduling points.  Trades context switch overhead
	  at the cost of non-preemptive durations of bottom half
	  processing.
		 
	  G-EDF/RM, C-EDF/RM ONLY for now!	 
		 
endchoice	   
	   

config NR_LITMUS_SOFTIRQD
	   int "Number of klitirqd."
	   depends on LITMUS_SOFTIRQD
	   range 1 4096
	   default "1"
	   help
	     Should be <= to the number of CPUs in your system.

config LITMUS_NVIDIA
	  bool "Litmus handling of NVIDIA interrupts."
	  depends on LITMUS_SOFTIRQD || LITMUS_PAI_SOFTIRQD
	  default n
	  help
	    Direct tasklets from NVIDIA devices to Litmus's klitirqd.

		If unsure, say No.

config NV_DEVICE_NUM
	   int "Number of NVIDIA GPUs."
	   depends on LITMUS_SOFTIRQD || LITMUS_PAI_SOFTIRQD
	   range 1 4096
	   default "1"
	   help
	     Should be (<= to the number of CPUs) and
		 (<= to the number of GPUs) in your system.

choice
	  prompt "CUDA/Driver Version Support"
	  default CUDA_4_0
	  depends on LITMUS_NVIDIA
	  help
	  	Select the version of CUDA/driver to support.
	
config CUDA_4_0
	  bool "CUDA 4.0"
	  depends on LITMUS_NVIDIA
	  help
	  	Support CUDA 4.0 RC2 (dev. driver version: x86_64-270.40)

config CUDA_3_2
	  bool "CUDA 3.2"
	  depends on LITMUS_NVIDIA
	  help
	  	Support CUDA 3.2 (dev. driver version: x86_64-260.24)

endchoice

endmenu

endmenu