| 1 | <?xml version='1.0' encoding='UTF-8'?> |
1 | <?xml version='1.0' encoding='UTF-8'?> |
| 2 | <!DOCTYPE guide SYSTEM "/dtd/guide.dtd"> |
2 | <!DOCTYPE guide SYSTEM "/dtd/guide.dtd"> |
| 3 | <!-- $Header: /var/cvsroot/gentoo/xml/htdocs/doc/en/gcc-optimization.xml,v 1.18 2010/07/27 00:24:29 nightmorph Exp $ --> |
3 | <!-- $Header: /var/cvsroot/gentoo/xml/htdocs/doc/en/gcc-optimization.xml,v 1.20 2012/07/24 12:12:51 swift Exp $ --> |
| 4 | |
4 | |
| 5 | <guide> |
5 | <guide> |
| 6 | <title>Compilation Optimization Guide</title> |
6 | <title>Compilation Optimization Guide</title> |
| 7 | |
7 | |
| 8 | <author title="Author"> |
8 | <author title="Author"> |
| 9 | <mail link="nightmorph"/> |
9 | <mail link="nightmorph"/> |
| 10 | </author> |
10 | </author> |
| 11 | |
11 | |
| 12 | <abstract> |
12 | <abstract> |
| 13 | This guide provides an introduction to optimizing compiled code using safe, sane |
13 | This guide provides an introduction to optimizing compiled code using safe, sane |
| 14 | CFLAGS and CXXFLAGS. It also as describes the theory behind optimizing in |
14 | CFLAGS and CXXFLAGS. It also as describes the theory behind optimizing in |
| 15 | general. |
15 | general. |
| 16 | </abstract> |
16 | </abstract> |
| 17 | |
17 | |
| 18 | <!-- The content of this document is licensed under the CC-BY-SA license --> |
18 | <!-- The content of this document is licensed under the CC-BY-SA license --> |
| 19 | <!-- See http://creativecommons.org/licenses/by-sa/2.5 --> |
19 | <!-- See http://creativecommons.org/licenses/by-sa/2.5 --> |
| 20 | <license/> |
20 | <license/> |
| 21 | |
21 | |
| 22 | <version>2</version> |
22 | <version>4</version> |
| 23 | <date>2010-07-26</date> |
23 | <date>2012-04-27</date> |
| 24 | |
24 | |
| 25 | <chapter> |
25 | <chapter> |
| 26 | <title>Introduction</title> |
26 | <title>Introduction</title> |
| 27 | <section> |
27 | <section> |
| 28 | <title>What are CFLAGS and CXXFLAGS?</title> |
28 | <title>What are CFLAGS and CXXFLAGS?</title> |
| 29 | <body> |
29 | <body> |
| 30 | |
30 | |
| 31 | <p> |
31 | <p> |
| 32 | CFLAGS and CXXFLAGS are environment variables that are used to tell the GNU |
32 | CFLAGS and CXXFLAGS are environment variables that are used to tell the GNU |
| 33 | Compiler Collection, <c>gcc</c>, what kinds of switches to use when compiling |
33 | Compiler Collection, <c>gcc</c>, what kinds of switches to use when compiling |
| 34 | source code. CFLAGS are for code written in C, while CXXFLAGS are for code |
34 | source code. CFLAGS are for code written in C, while CXXFLAGS are for code |
| 35 | written in C++. |
35 | written in C++. |
| 36 | </p> |
36 | </p> |
| 37 | |
37 | |
| 38 | <p> |
38 | <p> |
| … | |
… | |
| 45 | </p> |
45 | </p> |
| 46 | |
46 | |
| 47 | </body> |
47 | </body> |
| 48 | </section> |
48 | </section> |
| 49 | <section> |
49 | <section> |
| 50 | <title>How are they used?</title> |
50 | <title>How are they used?</title> |
| 51 | <body> |
51 | <body> |
| 52 | |
52 | |
| 53 | <p> |
53 | <p> |
| 54 | CFLAGS and CXXFLAGS can be used in two ways. First, they can be used |
54 | CFLAGS and CXXFLAGS can be used in two ways. First, they can be used |
| 55 | per-program with Makefiles generated by automake. |
55 | per-program with Makefiles generated by automake. |
| 56 | </p> |
56 | </p> |
| 57 | |
57 | |
| 58 | <p> |
58 | <p> |
| 59 | However, this should not be done when installing packages found in the Portage |
59 | However, this should not be done when installing packages found in the Portage |
| 60 | tree. Instead, set your CFLAGS and CXXFLAGS in <path>/etc/make.conf</path>. This |
60 | tree. Instead, set your CFLAGS and CXXFLAGS in <path>/etc/portage/make.conf</path>. This |
| 61 | way all packages will be compiled using the options you specify. |
61 | way all packages will be compiled using the options you specify. |
| 62 | </p> |
62 | </p> |
| 63 | |
63 | |
| 64 | <pre caption="CFLAGS in /etc/make.conf"> |
64 | <pre caption="CFLAGS in /etc/portage/make.conf"> |
| 65 | CFLAGS="-march=athlon64 -O2 -pipe" |
65 | CFLAGS="-march=athlon64 -O2 -pipe" |
| 66 | CXXFLAGS="${CFLAGS}" |
66 | CXXFLAGS="${CFLAGS}" |
| 67 | </pre> |
67 | </pre> |
| 68 | |
68 | |
| 69 | <p> |
69 | <p> |
| 70 | As you can see, CXXFLAGS is set to use all the options present in CFLAGS. This |
70 | As you can see, CXXFLAGS is set to use all the options present in CFLAGS. This |
| 71 | is what you'll want almost without fail. You shouldn't ever need to specify |
71 | is what you'll want almost without fail. You shouldn't ever need to specify |
| 72 | additional options in CXXFLAGS. |
72 | additional options in CXXFLAGS. |
| 73 | </p> |
73 | </p> |
| 74 | |
74 | |
| 75 | </body> |
75 | </body> |
| 76 | </section> |
76 | </section> |
| 77 | <section> |
77 | <section> |
| 78 | <title>Misconceptions</title> |
78 | <title>Misconceptions</title> |
| 79 | <body> |
79 | <body> |
| … | |
… | |
| 150 | <title>-march</title> |
150 | <title>-march</title> |
| 151 | <body> |
151 | <body> |
| 152 | |
152 | |
| 153 | <p> |
153 | <p> |
| 154 | The first and most important option is <c>-march</c>. This tells the compiler |
154 | The first and most important option is <c>-march</c>. This tells the compiler |
| 155 | what code it should produce for your processor <uri |
155 | what code it should produce for your processor <uri |
| 156 | link="http://en.wikipedia.org/wiki/Microarchitecture">architecture</uri> (or |
156 | link="http://en.wikipedia.org/wiki/Microarchitecture">architecture</uri> (or |
| 157 | <e>arch</e>); it says that it should produce code for a certain kind of CPU. |
157 | <e>arch</e>); it says that it should produce code for a certain kind of CPU. |
| 158 | Different CPUs have different capabilities, support different instruction sets, |
158 | Different CPUs have different capabilities, support different instruction sets, |
| 159 | and have different ways of executing code. The <c>-march</c> flag will instruct |
159 | and have different ways of executing code. The <c>-march</c> flag will instruct |
| 160 | the compiler to produce code specifically for your CPU, with all its |
160 | the compiler to produce code specifically for your CPU, with all its |
| 161 | capabilities, features, instruction sets, quirks, and so on. |
161 | capabilities, features, instruction sets, quirks, and so on. |
| 162 | </p> |
162 | </p> |
| 163 | |
163 | |
| 164 | <p> |
164 | <p> |
| 165 | Even though the CHOST variable in <path>/etc/make.conf</path> specifies the |
165 | Even though the CHOST variable in <path>/etc/portage/make.conf</path> specifies the |
| 166 | general architecture used, <c>-march</c> should still be used so that programs |
166 | general architecture used, <c>-march</c> should still be used so that programs |
| 167 | can be optimized for your specific processor. x86 and x86-64 CPUs (among others) |
167 | can be optimized for your specific processor. x86 and x86-64 CPUs (among others) |
| 168 | should make use of the <c>-march</c> flag. |
168 | should make use of the <c>-march</c> flag. |
| 169 | </p> |
169 | </p> |
| 170 | |
170 | |
| 171 | <p> |
171 | <p> |
| 172 | What kind of CPU do you have? To find out, run the following command: |
172 | What kind of CPU do you have? To find out, run the following command: |
| 173 | </p> |
173 | </p> |
| 174 | |
174 | |
| 175 | <pre caption="Examining CPU information"> |
175 | <pre caption="Examining CPU information"> |
| 176 | $ <i>cat /proc/cpuinfo</i> |
176 | $ <i>cat /proc/cpuinfo</i> |
| 177 | </pre> |
177 | </pre> |
| 178 | |
178 | |
| 179 | <p> |
179 | <p> |
| 180 | Now let's see <c>-march</c> in action. This example is for an older Pentium III |
180 | Now let's see <c>-march</c> in action. This example is for an older Pentium III |
| 181 | chip: |
181 | chip: |
| 182 | </p> |
182 | </p> |
| 183 | |
183 | |
| 184 | <pre caption="/etc/make.conf: Pentium III"> |
184 | <pre caption="/etc/portage/make.conf: Pentium III"> |
| 185 | CFLAGS="-march=pentium3" |
185 | CFLAGS="-march=pentium3" |
| 186 | CXXFLAGS="${CFLAGS}" |
186 | CXXFLAGS="${CFLAGS}" |
| 187 | </pre> |
187 | </pre> |
| 188 | |
188 | |
| 189 | <p> |
189 | <p> |
| 190 | Here's another one for a 64-bit AMD CPU: |
190 | Here's another one for a 64-bit AMD CPU: |
| 191 | </p> |
191 | </p> |
| 192 | |
192 | |
| 193 | <pre caption="/etc/make.conf: AMD64"> |
193 | <pre caption="/etc/portage/make.conf: AMD64"> |
| 194 | CFLAGS="-march=athlon64" |
194 | CFLAGS="-march=athlon64" |
| 195 | CXXFLAGS="${CFLAGS}" |
195 | CXXFLAGS="${CFLAGS}" |
| 196 | </pre> |
196 | </pre> |
| 197 | |
197 | |
| 198 | <p> |
198 | <p> |
| 199 | If you still aren't sure what kind of CPU you have, you may just want to use |
199 | If you still aren't sure what kind of CPU you have, you may just want to use |
| 200 | <c>-march=native</c>. When this flag is used, GCC will detect your processor and |
200 | <c>-march=native</c>. When this flag is used, GCC will detect your processor and |
| 201 | automatically set appropriate flags for it. <brite>However, this should not be |
201 | automatically set appropriate flags for it. <brite>However, this should not be |
| 202 | used if you intend to compile packages for a different CPU!</brite> |
202 | used if you intend to compile packages for a different CPU!</brite> |
| 203 | </p> |
203 | </p> |
| 204 | |
204 | |
| 205 | <p> |
205 | <p> |
| 206 | So if you're compiling packages on one computer, but intend to run them on a |
206 | So if you're compiling packages on one computer, but intend to run them on a |
| 207 | different computer (such as when using a fast computer to build for an older, |
207 | different computer (such as when using a fast computer to build for an older, |
| 208 | slower machine), then <e>do not</e> use <c>-march=native</c>. "Native" means |
208 | slower machine), then <e>do not</e> use <c>-march=native</c>. "Native" means |
| … | |
… | |
| 256 | </body> |
256 | </body> |
| 257 | </section> |
257 | </section> |
| 258 | <section> |
258 | <section> |
| 259 | <title>-O</title> |
259 | <title>-O</title> |
| 260 | <body> |
260 | <body> |
| 261 | |
261 | |
| 262 | <p> |
262 | <p> |
| 263 | Next up is the <c>-O</c> variable. This controls the overall level of |
263 | Next up is the <c>-O</c> variable. This controls the overall level of |
| 264 | optimization. This makes the code compilation take somewhat more time, and can |
264 | optimization. This makes the code compilation take somewhat more time, and can |
| 265 | take up much more memory, especially as you increase the level of optimization. |
265 | take up much more memory, especially as you increase the level of optimization. |
| 266 | </p> |
266 | </p> |
| 267 | |
267 | |
| 268 | <p> |
268 | <p> |
| 269 | There are five <c>-O</c> settings: <c>-O0</c>, <c>-O1</c>, <c>-O2</c>, |
269 | There are five <c>-O</c> settings: <c>-O0</c>, <c>-O1</c>, <c>-O2</c>, |
| 270 | <c>-O3</c>, and <c>-Os</c>. You should use only one of them in |
270 | <c>-O3</c>, and <c>-Os</c>. You should use only one of them in |
| 271 | <path>/etc/make.conf</path>. |
271 | <path>/etc/portage/make.conf</path>. |
| 272 | </p> |
272 | </p> |
| 273 | |
273 | |
| 274 | <p> |
274 | <p> |
| 275 | With the exception of <c>-O0</c>, the <c>-O</c> settings each activate several |
275 | With the exception of <c>-O0</c>, the <c>-O</c> settings each activate several |
| 276 | additional flags, so be sure to read the gcc manual's chapter on <uri |
276 | additional flags, so be sure to read the gcc manual's chapter on <uri |
| 277 | link="http://gcc.gnu.org/onlinedocs/gcc-4.4.4/gcc/Optimize-Options.html#Optimize-Options">optimization |
277 | link="http://gcc.gnu.org/onlinedocs/gcc-4.4.4/gcc/Optimize-Options.html#Optimize-Options">optimization |
| 278 | options</uri> to learn which flags are activated at each <c>-O</c> level, as |
278 | options</uri> to learn which flags are activated at each <c>-O</c> level, as |
| 279 | well as some explanations as to what they do. |
279 | well as some explanations as to what they do. |
| 280 | </p> |
280 | </p> |
| 281 | |
281 | |
| 282 | <p> |
282 | <p> |
| 283 | Let's examine each optimization level: |
283 | Let's examine each optimization level: |
| 284 | </p> |
284 | </p> |
| 285 | |
285 | |
| 286 | <ul> |
286 | <ul> |
| … | |
… | |
| 398 | link="http://en.wikipedia.org/wiki/MMX">MMX</uri>, and <uri |
398 | link="http://en.wikipedia.org/wiki/MMX">MMX</uri>, and <uri |
| 399 | link="http://en.wikipedia.org/wiki/3dnow">3DNow!</uri> instruction sets for x86 |
399 | link="http://en.wikipedia.org/wiki/3dnow">3DNow!</uri> instruction sets for x86 |
| 400 | and x86-64 architectures. These are useful primarily in multimedia, gaming, and |
400 | and x86-64 architectures. These are useful primarily in multimedia, gaming, and |
| 401 | other floating point-intensive computing tasks, though they also contain several |
401 | other floating point-intensive computing tasks, though they also contain several |
| 402 | other mathematical enhancements. These instruction sets are found in more modern |
402 | other mathematical enhancements. These instruction sets are found in more modern |
| 403 | CPUs. |
403 | CPUs. |
| 404 | </p> |
404 | </p> |
| 405 | |
405 | |
| 406 | <impo> |
406 | <impo> |
| 407 | Be sure to check if your CPU supports these by running <c>cat /proc/cpuinfo</c>. |
407 | Be sure to check if your CPU supports these by running <c>cat /proc/cpuinfo</c>. |
| 408 | The output will include any supported additional instruction sets. Note that |
408 | The output will include any supported additional instruction sets. Note that |
| 409 | <b>pni</b> is just a different name for SSE3. |
409 | <b>pni</b> is just a different name for SSE3. |
| 410 | </impo> |
410 | </impo> |
| 411 | |
411 | |
| 412 | <p> |
412 | <p> |
| 413 | You normally don't need to add any of these flags to <path>/etc/make.conf</path> |
413 | You normally don't need to add any of these flags to <path>/etc/portage/make.conf</path> |
| 414 | as long as you are using the correct <c>-march</c> (for example, |
414 | as long as you are using the correct <c>-march</c> (for example, |
| 415 | <c>-march=nocona</c> implies <c>-msse3</c>). Some notable exceptions are newer |
415 | <c>-march=nocona</c> implies <c>-msse3</c>). Some notable exceptions are newer |
| 416 | VIA and AMD64 CPUs that support instructions not implied by <c>-march</c> (such |
416 | VIA and AMD64 CPUs that support instructions not implied by <c>-march</c> (such |
| 417 | as SSE3). For CPUs like these you'll need to enable additional flags where |
417 | as SSE3). For CPUs like these you'll need to enable additional flags where |
| 418 | appropriate after checking the output of <c>cat /proc/cpuinfo</c>. |
418 | appropriate after checking the output of <c>cat /proc/cpuinfo</c>. |
| 419 | </p> |
419 | </p> |
| 420 | |
420 | |
| 421 | <note> |
421 | <note> |
| 422 | You should check the <uri |
422 | You should check the <uri |
| 423 | link="http://gcc.gnu.org/onlinedocs/gcc-4.4.4/gcc/i386-and-x86_002d64-Options.html#i386-and-x86_002d64-Options">list</uri> |
423 | link="http://gcc.gnu.org/onlinedocs/gcc-4.4.4/gcc/i386-and-x86_002d64-Options.html#i386-and-x86_002d64-Options">list</uri> |
| 424 | of x86 and x86-64-specific flags to see which of these instruction sets are |
424 | of x86 and x86-64-specific flags to see which of these instruction sets are |
| 425 | activated by the proper CPU type flag. If an instruction is listed, then you |
425 | activated by the proper CPU type flag. If an instruction is listed, then you |
| 426 | don't need to specify it; it will be turned on by using the proper <c>-march</c> |
426 | don't need to specify it; it will be turned on by using the proper <c>-march</c> |
| 427 | setting. |
427 | setting. |
| 428 | </note> |
428 | </note> |
| … | |
… | |
| 499 | } |
499 | } |
| 500 | </pre> |
500 | </pre> |
| 501 | |
501 | |
| 502 | <p> |
502 | <p> |
| 503 | As you can see, any value higher than 3 is treated as just <c>-O3</c>. |
503 | As you can see, any value higher than 3 is treated as just <c>-O3</c>. |
| 504 | </p> |
504 | </p> |
| 505 | |
505 | |
| 506 | </body> |
506 | </body> |
| 507 | </section> |
507 | </section> |
| 508 | <section> |
508 | <section> |
| 509 | <title>What about redundant flags?</title> |
509 | <title>What about redundant flags?</title> |
| 510 | <body> |
510 | <body> |
| 511 | |
511 | |
| 512 | <p> |
512 | <p> |
| 513 | Oftentimes CFLAGS and CXXFLAGS that are turned on at various <c>-O</c> levels |
513 | Oftentimes CFLAGS and CXXFLAGS that are turned on at various <c>-O</c> levels |
| 514 | are specified redundantly in <path>/etc/make.conf</path>. Sometimes this is done |
514 | are specified redundantly in <path>/etc/portage/make.conf</path>. Sometimes this is done |
| 515 | out of ignorance, but it is also done to avoid flag filtering or flag replacing. |
515 | out of ignorance, but it is also done to avoid flag filtering or flag replacing. |
| 516 | </p> |
516 | </p> |
| 517 | |
517 | |
| 518 | <p> |
518 | <p> |
| 519 | Flag filtering/replacing is done in many of the ebuilds in the Portage tree. It |
519 | Flag filtering/replacing is done in many of the ebuilds in the Portage tree. It |
| 520 | is usually done because packages fail to compile at certain <c>-O</c> levels, or |
520 | is usually done because packages fail to compile at certain <c>-O</c> levels, or |
| 521 | when the source code is too sensitive for any additional flags to be used. The |
521 | when the source code is too sensitive for any additional flags to be used. The |
| 522 | ebuild will either filter out some or all CFLAGS and CXXFLAGS, or it may replace |
522 | ebuild will either filter out some or all CFLAGS and CXXFLAGS, or it may replace |
| 523 | <c>-O</c> with a different level. |
523 | <c>-O</c> with a different level. |
| 524 | </p> |
524 | </p> |
| 525 | |
525 | |
| 526 | <p> |
526 | <p> |
| 527 | The <uri |
527 | The <uri |
| 528 | link="http://devmanual.gentoo.org/ebuild-writing/functions/src_compile/build-environment/index.html">Gentoo |
528 | link="http://devmanual.gentoo.org/ebuild-writing/functions/src_compile/build-environment/index.html">Gentoo |
| 529 | Developer Manual</uri> outlines where and how flag filtering/replacing works. |
529 | Developer Manual</uri> outlines where and how flag filtering/replacing works. |
| … | |
… | |
| 540 | |
540 | |
| 541 | <p> |
541 | <p> |
| 542 | However, <brite>this is not a smart thing to do</brite>. CFLAGS are filtered for |
542 | However, <brite>this is not a smart thing to do</brite>. CFLAGS are filtered for |
| 543 | a reason! When flags are filtered, it means that it is unsafe to build a package |
543 | a reason! When flags are filtered, it means that it is unsafe to build a package |
| 544 | with those flags. Clearly, it is <e>not</e> safe to compile your whole system |
544 | with those flags. Clearly, it is <e>not</e> safe to compile your whole system |
| 545 | with <c>-O3</c> if some of the flags turned on by that level will cause problems |
545 | with <c>-O3</c> if some of the flags turned on by that level will cause problems |
| 546 | with certain packages. Therefore, you shouldn't try to "outsmart" the developers |
546 | with certain packages. Therefore, you shouldn't try to "outsmart" the developers |
| 547 | who maintain those packages. <e>Trust the developers</e>. Flag filtering and |
547 | who maintain those packages. <e>Trust the developers</e>. Flag filtering and |
| 548 | replacing is done for your benefit! If an ebuild specifies alternative flags, |
548 | replacing is done for your benefit! If an ebuild specifies alternative flags, |
| 549 | then don't try to get around it. |
549 | then don't try to get around it. |
| 550 | </p> |
550 | </p> |
| 551 | |
551 | |
| 552 | <p> |
552 | <p> |
| 553 | You will most likely continue to run into problems when you build a package with |
553 | You will most likely continue to run into problems when you build a package with |
| 554 | unacceptable flags. When you report your troubles on Bugzilla, the flags you use |
554 | unacceptable flags. When you report your troubles on Bugzilla, the flags you use |
| 555 | in <path>/etc/make.conf</path> will be readily visible and you will be told to |
555 | in <path>/etc/portage/make.conf</path> will be readily visible and you will be told to |
| 556 | recompile without those flags. Save yourself the trouble of recompiling by not |
556 | recompile without those flags. Save yourself the trouble of recompiling by not |
| 557 | using redundant flags in the first place! Don't just automatically assume that |
557 | using redundant flags in the first place! Don't just automatically assume that |
| 558 | you know better than the developers. |
558 | you know better than the developers. |
| 559 | </p> |
559 | </p> |
| 560 | |
560 | |
| 561 | </body> |
561 | </body> |
| 562 | </section> |
562 | </section> |
| 563 | <section> |
563 | <section> |
| 564 | <title>What about LDFLAGS?</title> |
564 | <title>What about LDFLAGS?</title> |
| 565 | <body> |
565 | <body> |
| 566 | |
566 | |
| 567 | <p> |
567 | <p> |
| 568 | The Gentoo developers have already set basic, safe LDFLAGS in the base profiles, |
568 | The Gentoo developers have already set basic, safe LDFLAGS in the base profiles, |
| 569 | so you don't need to change them. |
569 | so you don't need to change them. |
| 570 | </p> |
570 | </p> |
| 571 | |
571 | |
| 572 | </body> |
572 | </body> |
| 573 | </section> |
573 | </section> |
| 574 | <section> |
574 | <section> |
| 575 | <title>Can I use per-package flags?</title> |
575 | <title>Can I use per-package flags?</title> |
| 576 | <body> |
576 | <body> |
| 577 | |
577 | |
| 578 | <p> |
|
|
| 579 | There is no supported method for using CFLAGS or other variables on a |
|
|
| 580 | per-package basis, though there are a few <uri |
|
|
| 581 | link="http://forums.gentoo.org/viewtopic-p-3832057.html#3832057">rather |
|
|
| 582 | abusive</uri> ways of trying force Portage to do so. |
|
|
| 583 | </p> |
|
|
| 584 | |
|
|
| 585 | <warn> |
578 | <warn> |
| 586 | You <e>should not</e> try to force Portage to use per-package flags, as it is |
579 | Using per-package flags complicates debugging and support. Make sure you mention |
| 587 | not in any way supported and will greatly complicate bug reports. Just set your |
580 | in your bug reports if you make use of this feature and what the changes are you |
| 588 | flags in <path>/etc/make.conf</path> to be used on a system-wide basis. |
581 | made. |
| 589 | </warn> |
582 | </warn> |
|
|
583 | |
|
|
584 | <p> |
|
|
585 | Information on how to use per-package environment variables (including CFLAGS) |
|
|
586 | is described in the <uri |
|
|
587 | link="/doc/en/handbook/handbook-amd64.xml?part=3&chap=6#doc_chap2">Gentoo |
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588 | Handbook, "Per-Package Environment Variables"</uri>. |
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589 | </p> |
| 590 | |
590 | |
| 591 | </body> |
591 | </body> |
| 592 | </section> |
592 | </section> |
| 593 | </chapter> |
593 | </chapter> |
| 594 | |
594 | |
| 595 | <chapter> |
595 | <chapter> |
| 596 | <title>Resources</title> |
596 | <title>Resources</title> |
| 597 | <section> |
597 | <section> |
| 598 | <body> |
598 | <body> |
| 599 | |
599 | |
| 600 | <p> |
600 | <p> |
| 601 | The following resources are of some help in further understanding optimization: |
601 | The following resources are of some help in further understanding optimization: |
| 602 | </p> |
602 | </p> |
| 603 | |
603 | |
| 604 | <ul> |
604 | <ul> |
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