TOP
Version 3.8beta1
William LeFebvre
with much help from others
Frequently Asked Questions and their Answers
GENERAL
1. What is top?
Top provies the user with a regularly updated display showing
information about the system and its top cpu-using processes. Think
of it as a full-screen "ps" output that gets updated at regular
intervals.
2. Where do I get the latest version of top?
The official site for top is "ftp.unixtop.org" in the directory
"/pub/top". Top is also a SourceForge project, and the most recent
releases are available on any of the SourceForge mirrors. The
SourceForge project page is at
http://sourceforge.net/projects/unixtop.
3. Is there a web page for top?
Yes. Point your browser at
http://www.unixtop.org. It includes all
documentation, a nice interactive display which describes the various
components of the output of top, web-based retrieval of the package,
year 2000 information, and other neat stuff.
4. Is there a mailing list or on-line bulletin board for top?
There is a mailing list used for general announcements regarding top,
including new releases. This mailing list is available to sourceforge
members and can be accessed from the unixtop sourceforge project
page. Visit SourceForge and search for the project "unixtop", then
click on "mailing lists". There are also on-line forums available
through SourceForge where members can post questions and comments.
5. What about Year 2000 compliance?
Top did not experience any problems with the transition to the year
2000. A full statement concerning top and the year 2000 can be found
in the file "Y2K" included with the distribution.
6. Will there be another major release of top? Will there be a top
version 4?
I have some great ideas for the next major release of top, and I very
much want to make those ideas a reality. What I don't have much of
these days is free time. But I will keep poking at it and I hope to
have top version 4.0 ready by the fall of 2006.
7. Does top really support multi-processor systems?
On platforms that support multiple processors, top is able to detect
and correctly summarize the information about those processors. What
top does not do is break down the cpu states summary (the third line
of the display) by cpu. Instead it collects the cpu state information
from all processors and combines them in to a single line. Some
vendors include a modified version of top that presents this
information for each cpu. Top 3.7 may have this functionality but it
is not present in the standard top 3.6 release.
8. Is top under CVS control? Can I access the sources via SourceForge
CVS or Subversion?
I maintain top using subversion, not CVS. Although I utilize my own
private subversion repository, it is regularly mirrored in to the
SourceForge Subversion repository. You can access the SourceForge
repository here:
https://svn.unixtop.org/unixtop/top-3.
COMPILING
9. We just upgraded our operating system to a new version and top broke.
What should we do?
Recompile it. Top is very sensitive to changes in internal kernel
data structures. It is not uncommon for a new version of the
operating system to include changes to kernel data structures.
RUNNING
10. I just finished compiling top and it works fine for root, but when I
try to run it as a regular user it either complains about files it
can't open or it doesn't display all the information it should. Did I
do something wrong?
Well, you're just not done. On many operating systems today, access
to many of the kernel memory devices and other system files is
restricted to either root or a particular group. The configure script
figures this out (usually) and makes sure that the "install" rule in
the Makefile will install top so that anyone can run it successfully.
However, you have to *install* it first. Do this with the command
"make install".
11. Top is (not) displaying idle processes and I don't (do) want it to.
This default has only changed about a dozen times, and I finally got
tired of people whining about it. Go read the manual page for the
current version and pay special attention to the description of the
"TOP" environment variable.
12. We have so much memory in our machine that the memory status display
(the fourth line) ends up being longer than 80 characters. This
completely messes up top's output. Is there a patch?
Most modules have been changed to use new memory formatting functions
which will display large values in terms of megabytes instead of
kilobytes. This should fix all occurences of this problem. Also note
that newer versions of top can use columns beyond 79, and understand
window resizes. So you can always make your window wider.
13. I tried to compile top with gcc and it doesn't work. I get
compilation errors in the include files, or I get an executable that
dumps core, or top displays incorrect numbers in some of the
displays. What's wrong?
Gnu CC likes very much to use its own include files. Not being a gcc
expert, I can't explain why it does this. But I can tell you that if
you upgrade your operating system (say from Solaris 2.6 to Solaris
2.7) after installing gcc, then the include files that gcc uses will
be incorrect, especially those found in the "sys" directory. Your
choices are: (1) rebuild and reinstall the "standard" include files
for gcc (look for scripts in the distribution called "fixincludes"
and "fixinc.svr4"), (2) compile machine.c with
"CFLAGS=-I/usr/include" then make the rest of the object files
normally, or (3) use a different compiler.
14. The cpu state percentages are all wrong, indicating that my machine
is using 95% system time when it is clearly idle. What's wrong?
This can happen if you compiled with gcc using the wrong include
files. See the previous question.
FREEBSD PROBLEMS
15. This version of top does not show individual threads with the "t" or
"H" commands. Instead it says "command not available." Why?
Previous versions of top attempted to support the display of
individual threads under FreeBSD through the use of the "t" command.
However, the FreeBSD kernel does not supply sufficient or correct
information on the individual threads within a process. So the data
that was being displayed was incorrect and misleading. Therefore, top
version 3.8 disables the use of this command to prevent the display
of incorrect information. FreeBSD 8.0 will correctly report
per-thread information and top version 3.8 supports the use of the
"t" command for version 8.0.
16. The "f" command (to display full command lines for the processes)
does not work and instead says "command not available". Why?
The current version of top is able to use sysctl to retrieve almost
all of the information it needs without having to open /dev/kmem. The
one piece of information not available via sysctl is the full command
line of each argument. If you run top as a regular user and it cannot
open /dev/kmem (in other words, it is not installed set-gid to the
kmem group) then it will disable the "f" command. Make sure the top
binary is installed with a group ownership of "kmem" and with the
set-gid bit on if you want the "f" command to work properly.
MACOSX PROBLEMS
17. I tried to configure top on my Mac OSX system and I got an error
claiming "macosx not supported". What up?
Since I don't have full time root access to a Mac OSX system I cannot
provide effective support for the platform. MacOSX uses Mach, and it
is very difficult to extract accurate system and process information
from the system. It takes a lot of trial and error, along with root
access. I have included the most up-to-date version of the macosx
module in the distribution, but I do not claim that it works. If you
want to try to use it, you can configure with "./configure
--with-module=macosx".
SUNOS PROBLEMS
18. I tried compiling top under SunOS version 4.1.x and it got compile
time errors or run time errors. Is there a patch?
If you try compiling top in a "System V environment" under SunOS
(that is, /usr/5bin is before /usr/bin on your path) then the
compilation may fail. This is mostly due to the fact that top thinks
its being compiled on a System V machine when it really isn't. The
only solution is to put /usr/bin and /usr/ucb before /usr/5bin on
your path and try again.
SOLARIS PROBLEMS
NOTE: the most common source of problems with top under Solaris is
the result of compiling it with the wrong front end. Make sure that
/usr/ucb is not on your path before attempting to compile top under
Solaris.
19. Is there somewhere I can get a pre-compiled package?
Yes. Although I don't provide pre-compiled binaries, you can get a
Sun-style package from www.sunfreeware.com.
20. Under Solaris 2, when I type "make", the system says "language
optional software package not installed." What's going on?
You tried to compile with /usr/ucb/cc. Make sure /usr/ucb is not on
your path. Furthermore, you do not have a Sun compiler installed on
your system. You need a compiler to make top. Either Sun's C compiler
or the Gnu C compiler will work fine.
21. Under Solaris 2, when I run top as root it only shows root processes,
or it only shows processes with a PID less than 1000. It refuses to
show anything else. What do I do?
You probably compiled it with /usr/ucb/cc instead of the real C
compiler. /usr/ucb/cc is a cc front end that compiles programs in BSD
source-level compatability mode. You do not want that. Make sure that
/usr/ucb is not on your path and try compiling top again.
22. Under Solaris 2, I compiled top using what I am sure is the correct
compiler but when I try to run it it complains about missing dynamic
libraries. What is wrong?
Check to see if you have LD_LIBRARY_PATH defined in your shell. If
you do, make sure that /usr/ucblib is not on the path anywhere. Then
try compiling top again.
23. Under Solaris 2, when I try to run top it complains that it can't
open the library "libucb.so.1". So I changed the LIBS line in
m_sunos5.c to include -R/usr/ucblib to make sure that the dynamic
linker will look there when top runs. I figured this was just an
oversight. Was I right?
No, you were not right. As distributed, top requires no alterations
for successful compilation and operations under any release of
Solaris 2. You probably compiled top with /usr/ucb/cc instead of the
real C compiler. See FAQ 22 for more details.
24. On my 64-bit system some processes show up with incorrect information
(such as zero memory).
If you are running a 64-bit system, then you need to make sure that
you are running the 64-bit top binary. Top's configure script
attempts to detect 64-bit systems, and will automatically generate
both 32-bit and 64-bit binaries on such systems. If you use or
install the 32-bit binary on a 64-bit system top will still run but
will not produce the correct results. This will also happen if you
configure your distribution on a 32-bit system then compile with that
configuration on a 64-bit system. You must configure and compile on
the same system. For Sparc systems the 32-bit binary will be created
in the subdirectory "sparcv7" and the 64-bit binary will be created
in the subdirectory "sparcv9". For Intel systems the directories will
be "i386" (32-bit) and "amd64" (64-bit). In all cases a copy of
/usr/lib/isaexec is made in the main directory and called "top". This
program will choose the correct binary to run from one of these
subdirectories. See isaexec(3c) for more details.
25. Can I install both 32-bit and 64-bit binaries on a central file
server and have machines which mount it automatically use the correct
one?
Yes. If you configure and compile on a 64-bit system, top's configure
script and makefile will automatically create both 32-bit and 64-bit
binaries. The "install" rule in the makefile will install these
binaries in subdirectories of /usr/local/bin appropriate to the
architecture (sparcv7/sparcv9 or i386/amd64) then create a copy of
/usr/lib/isaexec named "top" in /usr/local/bin to ensure that the
appropriate is run when a user types "top". If you make sure that you
configure and compile on a 64-bit system, then "make install" will do
the right thing.
26. This version of top show less available swap space than previous
versions. Why does it no longer match the output of the swap summary
produced with "swap -s"?
Starting with version 3.6 of top, the amount of swap space reported
by top has been changed to reflect only disk-based swap space. The
swap summary produced with "swap -s" also includes memory-based swap
space. This changed was made for several reasons. It makes the
display under Solaris more like those of other operating systems. The
display is more what users expect (except those used to previous
versions of top). Most importantly, "swap -s" gets its data via an
undocumented system interface. Now that top no longer displays that
data it can use publically documented and maintained system
interfaces to retrieve its data.
SVR4-DERIVED PROBLEMS
27. When I run top on my SVR4-derived operating system, it displays all
the system information at the top but does not display any process
information (or only displays process information for my own
processes). Yet when I run it as root, everything works fine. What's
wrong?
Your system probably uses the pseudo file system "/proc", which is by
default only accessible by root. Top needs to be installed setuid
root on such systems if it is going to function correctly for normal
users.
SVR42 PROBLEMS
28. The memory display doesn't work right. Why?
This is a known bug with the svr42 module. The problem has been
traced down to a potential bug in the "mem" driver. The author of the
svr42 module is working on a fix.
STILL STUCK
29. I'm still stuck. To whom do I report problems with top?
The most common problems are caused by top's sensitivity to internal
kernel data structures. So make sure that you are using the right
include files, and make sure that you test out top on the same
machine where you compiled it. Sun's BSD Source Compatability Mode is
also a common culprit. Make sure you aren't using either /usr/ucb/cc
or any of the libraries in /usr/ucblib. Finally, make sure you are
using the correct module. If there does not appear to be one
appropriate for your computer, then top probably will not work on
your system.
If after reading all of this file and checking everything you can you
are still stuck, then please use SourceForge to submit a support
request or a bug. Top is supported by the SourceForge project named
"unixtop". On SourceForge you will find defect tracking, a mailing
list, and on-line forums. You can also contact the author through
SourceForge.
