5 with much help from others
7 Frequently Asked Questions and their Answers
15 Top provies the user with a regularly updated display showing
16 information about the system and its top cpu-using processes. Think
17 of it as a full-screen "ps" output that gets updated at regular
20 2. Where do I get the latest version of top?
22 The official site for top is "ftp.unixtop.org" in the directory
23 "/pub/top". Top is also a SourceForge project, and the most recent
24 releases are available on any of the SourceForge mirrors. The
25 SourceForge project page is at
26 http://sourceforge.net/projects/unixtop.
28 3. Is there a web page for top?
30 Yes. Point your browser at http://www.unixtop.org. It includes all
31 documentation, a nice interactive display which describes the various
32 components of the output of top, web-based retrieval of the package,
33 year 2000 information, and other neat stuff.
35 4. Is there a mailing list or on-line bulletin board for top?
37 There is a mailing list used for general announcements regarding top,
38 including new releases. This mailing list is available to sourceforge
39 members and can be accessed from the unixtop sourceforge project
40 page. Visit SourceForge and search for the project "unixtop", then
41 click on "mailing lists". There are also on-line forums available
42 through SourceForge where members can post questions and comments.
44 5. What about Year 2000 compliance?
46 Top did not experience any problems with the transition to the year
47 2000. A full statement concerning top and the year 2000 can be found
48 in the file "Y2K" included with the distribution.
50 6. Will there be another major release of top? Will there be a top
53 I have some great ideas for the next major release of top, and I very
54 much want to make those ideas a reality. What I don't have much of
55 these days is free time. But I will keep poking at it and I hope to
56 have top version 4.0 ready by the fall of 2006.
58 7. Does top really support multi-processor systems?
60 On platforms that support multiple processors, top is able to detect
61 and correctly summarize the information about those processors. What
62 top does not do is break down the cpu states summary (the third line
63 of the display) by cpu. Instead it collects the cpu state information
64 from all processors and combines them in to a single line. Some
65 vendors include a modified version of top that presents this
66 information for each cpu. Top 3.7 may have this functionality but it
67 is not present in the standard top 3.6 release.
69 8. Is top under CVS control? Can I access the sources via SourceForge
72 I maintain top using subversion, not CVS. Although I utilize my own
73 private subversion repository, it is regularly mirrored in to the
74 SourceForge Subversion repository. You can access the SourceForge
75 repository here: https://svn.unixtop.org/unixtop/top-3.
80 9. We just upgraded our operating system to a new version and top broke.
83 Recompile it. Top is very sensitive to changes in internal kernel
84 data structures. It is not uncommon for a new version of the
85 operating system to include changes to kernel data structures.
90 10. I just finished compiling top and it works fine for root, but when I
91 try to run it as a regular user it either complains about files it
92 can't open or it doesn't display all the information it should. Did I
95 Well, you're just not done. On many operating systems today, access
96 to many of the kernel memory devices and other system files is
97 restricted to either root or a particular group. The configure script
98 figures this out (usually) and makes sure that the "install" rule in
99 the Makefile will install top so that anyone can run it successfully.
100 However, you have to *install* it first. Do this with the command
103 11. Top is (not) displaying idle processes and I don't (do) want it to.
105 This default has only changed about a dozen times, and I finally got
106 tired of people whining about it. Go read the manual page for the
107 current version and pay special attention to the description of the
108 "TOP" environment variable.
110 12. We have so much memory in our machine that the memory status display
111 (the fourth line) ends up being longer than 80 characters. This
112 completely messes up top's output. Is there a patch?
114 Most modules have been changed to use new memory formatting functions
115 which will display large values in terms of megabytes instead of
116 kilobytes. This should fix all occurences of this problem. Also note
117 that newer versions of top can use columns beyond 79, and understand
118 window resizes. So you can always make your window wider.
120 13. I tried to compile top with gcc and it doesn't work. I get
121 compilation errors in the include files, or I get an executable that
122 dumps core, or top displays incorrect numbers in some of the
123 displays. What's wrong?
125 Gnu CC likes very much to use its own include files. Not being a gcc
126 expert, I can't explain why it does this. But I can tell you that if
127 you upgrade your operating system (say from Solaris 2.6 to Solaris
128 2.7) after installing gcc, then the include files that gcc uses will
129 be incorrect, especially those found in the "sys" directory. Your
130 choices are: (1) rebuild and reinstall the "standard" include files
131 for gcc (look for scripts in the distribution called "fixincludes"
132 and "fixinc.svr4"), (2) compile machine.c with
133 "CFLAGS=-I/usr/include" then make the rest of the object files
134 normally, or (3) use a different compiler.
136 14. The cpu state percentages are all wrong, indicating that my machine
137 is using 95% system time when it is clearly idle. What's wrong?
139 This can happen if you compiled with gcc using the wrong include
140 files. See the previous question.
145 15. This version of top does not show individual threads with the "t" or
146 "H" commands. Instead it says "command not available." Why?
148 Previous versions of top attempted to support the display of
149 individual threads under FreeBSD through the use of the "t" command.
150 However, the FreeBSD kernel does not supply sufficient or correct
151 information on the individual threads within a process. So the data
152 that was being displayed was incorrect and misleading. Therefore, top
153 version 3.8 disables the use of this command to prevent the display
154 of incorrect information. FreeBSD 8.0 will correctly report
155 per-thread information and top version 3.8 supports the use of the
156 "t" command for version 8.0.
158 16. The "f" command (to display full command lines for the processes)
159 does not work and instead says "command not available". Why?
161 The current version of top is able to use sysctl to retrieve almost
162 all of the information it needs without having to open /dev/kmem. The
163 one piece of information not available via sysctl is the full command
164 line of each argument. If you run top as a regular user and it cannot
165 open /dev/kmem (in other words, it is not installed set-gid to the
166 kmem group) then it will disable the "f" command. Make sure the top
167 binary is installed with a group ownership of "kmem" and with the
168 set-gid bit on if you want the "f" command to work properly.
173 17. I tried to configure top on my Mac OSX system and I got an error
174 claiming "macosx not supported". What up?
176 Since I don't have full time root access to a Mac OSX system I cannot
177 provide effective support for the platform. MacOSX uses Mach, and it
178 is very difficult to extract accurate system and process information
179 from the system. It takes a lot of trial and error, along with root
180 access. I have included the most up-to-date version of the macosx
181 module in the distribution, but I do not claim that it works. If you
182 want to try to use it, you can configure with "./configure
183 --with-module=macosx".
188 18. I tried compiling top under SunOS version 4.1.x and it got compile
189 time errors or run time errors. Is there a patch?
191 If you try compiling top in a "System V environment" under SunOS
192 (that is, /usr/5bin is before /usr/bin on your path) then the
193 compilation may fail. This is mostly due to the fact that top thinks
194 its being compiled on a System V machine when it really isn't. The
195 only solution is to put /usr/bin and /usr/ucb before /usr/5bin on
196 your path and try again.
202 NOTE: the most common source of problems with top under Solaris is
203 the result of compiling it with the wrong front end. Make sure that
204 /usr/ucb is not on your path before attempting to compile top under
207 19. Is there somewhere I can get a pre-compiled package?
209 Yes. Although I don't provide pre-compiled binaries, you can get a
210 Sun-style package from www.sunfreeware.com.
212 20. Under Solaris 2, when I type "make", the system says "language
213 optional software package not installed." What's going on?
215 You tried to compile with /usr/ucb/cc. Make sure /usr/ucb is not on
216 your path. Furthermore, you do not have a Sun compiler installed on
217 your system. You need a compiler to make top. Either Sun's C compiler
218 or the Gnu C compiler will work fine.
220 21. Under Solaris 2, when I run top as root it only shows root processes,
221 or it only shows processes with a PID less than 1000. It refuses to
222 show anything else. What do I do?
224 You probably compiled it with /usr/ucb/cc instead of the real C
225 compiler. /usr/ucb/cc is a cc front end that compiles programs in BSD
226 source-level compatability mode. You do not want that. Make sure that
227 /usr/ucb is not on your path and try compiling top again.
229 22. Under Solaris 2, I compiled top using what I am sure is the correct
230 compiler but when I try to run it it complains about missing dynamic
231 libraries. What is wrong?
233 Check to see if you have LD_LIBRARY_PATH defined in your shell. If
234 you do, make sure that /usr/ucblib is not on the path anywhere. Then
235 try compiling top again.
237 23. Under Solaris 2, when I try to run top it complains that it can't
238 open the library "libucb.so.1". So I changed the LIBS line in
239 m_sunos5.c to include -R/usr/ucblib to make sure that the dynamic
240 linker will look there when top runs. I figured this was just an
241 oversight. Was I right?
243 No, you were not right. As distributed, top requires no alterations
244 for successful compilation and operations under any release of
245 Solaris 2. You probably compiled top with /usr/ucb/cc instead of the
246 real C compiler. See FAQ 22 for more details.
248 24. On my 64-bit system some processes show up with incorrect information
249 (such as zero memory).
251 If you are running a 64-bit system, then you need to make sure that
252 you are running the 64-bit top binary. Top's configure script
253 attempts to detect 64-bit systems, and will automatically generate
254 both 32-bit and 64-bit binaries on such systems. If you use or
255 install the 32-bit binary on a 64-bit system top will still run but
256 will not produce the correct results. This will also happen if you
257 configure your distribution on a 32-bit system then compile with that
258 configuration on a 64-bit system. You must configure and compile on
259 the same system. For Sparc systems the 32-bit binary will be created
260 in the subdirectory "sparcv7" and the 64-bit binary will be created
261 in the subdirectory "sparcv9". For Intel systems the directories will
262 be "i386" (32-bit) and "amd64" (64-bit). In all cases a copy of
263 /usr/lib/isaexec is made in the main directory and called "top". This
264 program will choose the correct binary to run from one of these
265 subdirectories. See isaexec(3c) for more details.
267 25. Can I install both 32-bit and 64-bit binaries on a central file
268 server and have machines which mount it automatically use the correct
271 Yes. If you configure and compile on a 64-bit system, top's configure
272 script and makefile will automatically create both 32-bit and 64-bit
273 binaries. The "install" rule in the makefile will install these
274 binaries in subdirectories of /usr/local/bin appropriate to the
275 architecture (sparcv7/sparcv9 or i386/amd64) then create a copy of
276 /usr/lib/isaexec named "top" in /usr/local/bin to ensure that the
277 appropriate is run when a user types "top". If you make sure that you
278 configure and compile on a 64-bit system, then "make install" will do
281 26. This version of top show less available swap space than previous
282 versions. Why does it no longer match the output of the swap summary
283 produced with "swap -s"?
285 Starting with version 3.6 of top, the amount of swap space reported
286 by top has been changed to reflect only disk-based swap space. The
287 swap summary produced with "swap -s" also includes memory-based swap
288 space. This changed was made for several reasons. It makes the
289 display under Solaris more like those of other operating systems. The
290 display is more what users expect (except those used to previous
291 versions of top). Most importantly, "swap -s" gets its data via an
292 undocumented system interface. Now that top no longer displays that
293 data it can use publically documented and maintained system
294 interfaces to retrieve its data.
297 SVR4-DERIVED PROBLEMS
299 27. When I run top on my SVR4-derived operating system, it displays all
300 the system information at the top but does not display any process
301 information (or only displays process information for my own
302 processes). Yet when I run it as root, everything works fine. What's
305 Your system probably uses the pseudo file system "/proc", which is by
306 default only accessible by root. Top needs to be installed setuid
307 root on such systems if it is going to function correctly for normal
313 28. The memory display doesn't work right. Why?
315 This is a known bug with the svr42 module. The problem has been
316 traced down to a potential bug in the "mem" driver. The author of the
317 svr42 module is working on a fix.
322 29. I'm still stuck. To whom do I report problems with top?
324 The most common problems are caused by top's sensitivity to internal
325 kernel data structures. So make sure that you are using the right
326 include files, and make sure that you test out top on the same
327 machine where you compiled it. Sun's BSD Source Compatability Mode is
328 also a common culprit. Make sure you aren't using either /usr/ucb/cc
329 or any of the libraries in /usr/ucblib. Finally, make sure you are
330 using the correct module. If there does not appear to be one
331 appropriate for your computer, then top probably will not work on
334 If after reading all of this file and checking everything you can you
335 are still stuck, then please use SourceForge to submit a support
336 request or a bug. Top is supported by the SourceForge project named
337 "unixtop". On SourceForge you will find defect tracking, a mailing
338 list, and on-line forums. You can also contact the author through
tuxillo's projects / dragonfly.git / blob