1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
|
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 "Performance Hacks"
config CPU_SCHED_BIAS
bool "Tasks prefer previous CPU(s)."
default n
help
Allow tasks to be rescheduled on their previously used CPU(s) if that
CPU(s) is not currently not executing real-time work. This may improve
performance through the possible preservation of cache affinity.
Warning: May make bugs harder to find as tasks will migrate less
frequently.
Only bias towards previously used CPU is currently implemented. In the
future: bias on CPU topology.
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
|
