We have created an mdb module and simple shell script wrapper that can

be used to get a list of the clients connected to an X server, the

sequence number of the last request it sent, and in the case of most

local clients, their process id. This can be run against either an

core dump or a live server.

This can be useful for trying to figure out which client is

responsible for the reads and writes you see to a certain file

descriptor in a truss and similar debugging activities. The sequence

number will basically be a count of the number of requests an X client

has sent during its lifetime.

Building

--------

Due to the different data structures used, there are different versions

for X servers based on the Xsun source (those delivered in /usr/openwin)

and for those based on the Xorg source (those delivered in /usr/X11).

Building these depends on headers in the X server sources which aren't

delivered in each server's SDK headers, so the Xsun one requires the

closed Xsun source, and the Xorg one requires at least having done 

"make source configure" in the open-src/xserver/xorg directory.

Once the sources are in place "make build_Xsun" builds the modules for

Xsun and creates a SVR4 package named XSUNdebug.   "make build_Xorg" 

similarly creates XORGdebug.   In the instructions that follow, if you're

using the Xsun version replace "XORG" with "XSUN" and "Xorg" with "Xsun".

Installation

------------

To install, simply copy the package directory to the target

machine and run (as root):

 # pkgadd -d . XORGdebug

(or Xsun debug as appropriate).

Scripts

-------

To run the simple front end script, simply find the process id of the running 

Xserver and run:

	/opt/XORGdebug/bin/list_Xorg_clients processid

You will get output like this:

max_clients = 1024

CLIENT SEQUENCE #  FD  PIDS

    0           0  -1 9719 

    1           8  15  ??? - NULL OsCommPtr->process

    2           9  16 9721 

    4           8  18  ??? - NULL OsCommPtr->process

    5          17 ??? - NULL ClientPtr->osPrivate

    6          14  19 9763 

    7          71  20 9814 

    8          13  21 9819 

    9          17  22 9836 

   10      501747  23 9837 

   11         147  24 9837 

   12          11  25 9837 

   13        9676  26 9843 

   14       38347  27 9843 

   15          11  28 9843 

   16       13251  29 9846 9857 9861 9871 

   18        5299  31 9847 9891 9894 9900 9904 9922 

   19        2397  32 9879 

   21          11  34 9879 

   23    34389507  36 9885 

1342  /usr/dt/bin/dtlogin -daemon

  9719  /usr/openwin/bin/Xorg :0 -depth 24 -nobanner -auth /var/dt/A:0-epayvc

  9721  /usr/openwin/bin/fbconsole -d :0

  9720  /usr/dt/bin/dtlogin -daemon

    9741  /bin/ksh /usr/dt/bin/Xsession

      9819  /usr/dt/bin/sdt_shell -c unsetenv _ PWD;             unsetenv DT;  

        9821  -csh -c unsetenv _ PWD;             unsetenv DT;      setenv DISP

          9837  /usr/dt/bin/dtsession

            9843  dtwm

            9846  /usr/dt/bin/dtterm -session dtb2aitb -C -ls

              9857  -csh

              9861  -csh

              9871  -csh

            9847  /usr/dt/bin/dtterm -session dtP2aqtb -C -ls

              9891  -csh

              9894  -csh

              9900  -csh

              9904  -csh

              9922  -csh

            9879  dtfile -session dtqRaOFb

              9949  dtfile -session dtqRaOFb

            9885  sdtperfmeter -f -H -t cpu -t disk -s 1 -name fpperfmeter

9836  /usr/dt/bin/ttsession

The output at the end comes from ptree. From this example we can see

the busiest client in this CDE session has been sdtperfmeter since it

has sent 34389507 X requests in order to update the performance meter

once a second. (This session was running for 6 days before this output

was taken.)

Similar scripts are included for listing which clients have active device

or server grabs:

	/opt/XORGdebug/bin/list_Xorg_devicegrab_client

	/opt/XORGdebug/bin/list_Xorg_servergrab_client

They should be documented here, but haven't been yet.

Debugging with mdb

------------------

The mdb module can also be used directly in an mdb debugging session

on either a live server or a core file.

Two dcmds are provided, a "walker" which simply iterates over the

entries in the Xorg clients table, and a command that prints the

information for each client.

You can run like this:

mdb -L %o:/opt/XORGdebug/lib/%i -p 9719

Loading modules: [ ld.so.1 libc.so.1 ]

> ::load Xorg_clients

> ::walk client_walk

max_clients = 1024

1b7db8

1b7dbc

1b7dc0

[...]

> 1b7dc0  ::client_pids

CLIENT SEQUENCE #  FD  PIDS

    2           9  16 9721 

If you run ::client_pids without an address in front, it will

automatically call the client_walk to list the information for all the

clients.

A similar module is provided for walking the device grabs table,

Xorg_device_grabs.so.  It should be documented here, but hasn't been yet.

=============================================================================

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