1 karl 1.1 TITLE: REDUCING PEGASUS STATIC FOOTPRINT
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3 Author: M. Brasher, Karl Schopmeyer
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5 Date: 3 Aug 2006
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7 This readme describes how to build Pegasus for the smallest possible footprint.
8 It defines a number of changes that you can make to reduce both the Pegasus
9 code size and class repository size.
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11 COMPILER ISSUES
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13 1. When using GCC, always use 4.0 or later. There are two advantages:
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15 (*) GCC 4 does a better job of optimizing C++ for size.
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17 (*) Pegasus limits symbol visisibility from shared libraries using
18 special features of GCC 4.0 and later.
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20 2. If you can't use at least GCC 4.0, at least try to use GCC 3.0 or
21 better. GCC 3.0 introduced the -fno-enforce-eh-specs option, which
22 karl 1.1 reduces the object code size of Pegasus by 20%.
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24 3. On 64-bit Intel systems, build 32-bit to save around 30% of the
25 footprint (64-bit code is large since the operands are twice as
26 long). This technique of course will produces slower code.
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28 REPOSITORY SIZE REDUCTION
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30 1. Configure Pegasus to use a binary CIM repository. This is done by
31 setting the PEGASUS_REPOSITORY_MODE environment variable to BIN.
32 This technique will improve the performance of the repository. There is
33 a readme that describes this feature.
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35 2. Configure Pegasus to compress the CIM repository. This is done by
36 setting the PEGASUS_ENABLE_COMPRESSED_REPOSITORY environment variable
37 to true. This technique will slightly degrade the performance of the
38 repository but reduce size by better than 50%. There is a readme
39 that describes this feature and how to set it up.
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41 COMPILE OPTIONS
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43 karl 1.1 1. Be sure that the PEGASUS_DEBUG environment variable is not defined
44 when you build Pegasus. Otherwise, you will end up with a much
45 larger image.
46 2. Define PEGASUS_NO_FILE_LINE_TRACE=true to eliminate __FILE__ and
47 __LINE__ macros from tracer expansion. This reduces the overall size
48 by about 50k by not including the line and file information into
49 the code. However, it means the resulting traces do not have this
50 information in the trace output.
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52 3. Turn off the compile of the trace completely. The flag PEGASUS_DISABLE_TRACE
53 will force the compile without any of the trace code. This can save at least
54 100k but means that there is no means to trace including the XMLIO traces.
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56 4. Define the PEGASUS_OPTIMIZE_FOR_SIZE environment variable
57 that causes Pegasus to build with -Os rather than -O2.
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59 5. Disable use of OOP. This eliminates the extra use of memory that occurs because
60 of the extra process created to load providers.
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62 STATIC BUILD VS. DYNAMIC BUILD
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64 karl 1.1 Originally Pegasus was built with a series of dynamic libraries, one for each
65 source directory (common, WQL, CQL, etc.). While this has proven a good tool
66 for developers the result is a significantly larger footprint for a number of
67 reasons. See PEP 253 for more information. Today you have the choice of building
68 the dynamic version or a static build which results in a much smaller footprint.
69 Generally the static build can save up to 40% in code footprint.
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71 The same basic build mechanism is used for both static and dynamic builds
72 with the choice being controlled by the use of two variables:
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74 PEGASUS_USE_STATIC_LIBRARIES - The environment variable
75 PEGASUS_USE_STATIC_LIBRARIES if it exists will result in a static build.
76 In order to determine which of the libraries go into the static build, a
77 second variable is used in the Makefile for the libraries that are to be
78 included in the executable.
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80 STATIC - Setting the variable STATIC=1 in the Makefile for a Pegasus
81 component causes that component to be included in the static executable
82 instead of building a shared library.
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84 As part of the definition of the static build mechanisms into the build
85 karl 1.1 environment, a lot of work was put into determining which of the existing
86 libraries could logically be in the executable since this means that they
87 are NOT available as shared libraries for use with providers and clients.
88
89 Currently the following libraries are in the static build as supplied with
90 the CVS Pegasus 2.6 checkout. Different users may elect to either add or remove
91 some of these libraries from the static build depending on their needs for
92 the availability of shared libraries for providers or clients..
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94 src/Pegasus/Server
95 src/Pegasus/Server/ProviderRegistrationManager
96 src/Pegasus/Security/Authentication
97 src/Pegasus/Security/UserManager
98 src/Pegasus/WQL
99 src/Pegasus/ProviderManager2
100 src/Pegasus/ProviderManager2/Default
101 src/Pegasus/IndicationService
102 src/Pegasus/ControlProviders/QueryCapabilitiesProvider
103 src/Pegasus/ControlProviders/NamespaceProvider
104 src/Pegasus/ControlProviders/Statistic
105 src/Pegasus/ControlProviders/UserAuthProvider
106 karl 1.1 src/Pegasus/ControlProviders/InteropProvider
107 src/Pegasus/ControlProviders/ConfigSettingProvider
108 src/Pegasus/ControlProviders/ProviderRegistrationProvider
109 src/Pegasus/Repository
110 src/Pegasus/ExportServer
111 src/Pegasus/HandlerService
112 src/Pegasus/Query/QueryExpression
113 src/Pegasus/Query/QueryCommon
114 src/Pegasus/CQL
115 src/Service
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117 NOTE: To see this list for yourself, grep -r Makefiles for STATIC=1.
118 NOTE: This list may change with time.
119
120 The components that remain dynamic libraries with are as follows:
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122 src/Pegasus/Common
123 src/Pegasus/Client
124 src/Pegasus/Config
125 src/Pegasus/Provider
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127 karl 1.1 This list represents the libraries required by providers.
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129 Building with the static build options does result in static builds for the client
130 utilities which might include the static libraries which means that some client
131 utilities could be significantly larger.
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133 Today you only gain if you do not use the out-of-process providers (OOP) feature
134 because if you build static, the resulting remote agent is effectivly as large
135 as the server because of all the static libraries that must be built into it.
136
137 The steps to create a static build instead of the dynamic build:
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139
140 1. Set the PEGASUS_USE_STATIC_LIBRARIES environment variable to true to
141 cause Pegasus to use static libraries where appropriate (rather than
142 dynamic libraries).
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144
145 2. Rebuild Pegasus. This will create a single executable for the server
146 and dynamic libraries for those components not defined to be included
147 in the static build.
148 karl 1.1
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