%defs; ]> AlanCoopersmith Oracle Corporation Solaris Engineering X.Org Xserver
version &xserver.version; Copyright (c) 2005, 2006, 2007, 2010, Oracle and/or
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EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES
OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
DEALINGS IN THE SOFTWARE. This page provides details on a statically defined
user application tracing provider for the DTrace facility in Solaris 10, MacOS
X 10.5, and later releases. This provider instruments various points in the X
server, to allow tracing what client applications are up to. The provider was
integrated into the X.Org git master repository with Solaris 10 & OpenSolaris
support for the Xserver 1.4 release, released in 2007 with X11R7.3. Support for
DTrace on MacOS X was added in Xserver 1.7. These probes expose the request and
reply structure of the X protocol between clients and the X server, so an
understanding of that basic nature will aid in learning how to use these
probes. Due to the way User-Defined DTrace probes work, arguments to these
probes all bear undistinguished names of arg0, arg1, arg2, etc. These tables
should help you determine what the real data is for each of the probe
arguments.

Probe name Description arg0 arg1 arg2 arg3 arg4 Request Probes request-start
Called just before processing each client request. requestName requestCode
requestLength clientId requestBuffer request-done Called just after processing
each client request. requestName requestCode sequenceNumber clientId resultCode
Event Probes send-event Called just before send each event to a client.
clientId eventCode eventBuffer Client Connection Probes client-connect Called
when a new connection is opened from a client clientId clientFD client-auth
Called when client authenticates (normally just after connection opened)
clientId clientAddr clientPid clientZoneId client-disconnect Called when a
client connection is closed clientId Resource Allocation Probes resource-alloc
Called when a new resource (pixmap, gc, colormap, etc.) is allocated resourceId
resourceTypeId resourceValue resourceTypeName resource-free Called when a
resource is freed resourceId resourceTypeId resourceValue resourceTypeName

To access data in arguments of type string, you will need to use copyinstr().
To access data buffers referenced via uintptr_t's, you will need to use copyin
().

Argument name Type Description clientAddr string String representing address
client connected from clientFD int X server's file descriptor for server side
of each connection clientId int Unique integer identifier for each connection
to the X server clientPid pid_t Process id of client, if connection is local
(from getpeerucred()) clientZoneId zoneid_t Solaris: Zone id of client, if
connection is local (from getpeerucred()) eventBuffer uintptr_t Pointer to
buffer containing X event - decode using structures in <X11/Xproto.h> and
similar headers for each extension eventCode uint8_t Event number of X event
resourceId uint32_t X resource id (XID) resourceTypeId uint32_t Resource type
id resourceTypeName string String representing X resource type ("PIXMAP", etc.)
resourceValue uintptr_t Pointer to data for X resource resultCode int Integer
code representing result status of request requestBuffer uintptr_t Pointer to
buffer containing X request - decode using structures in <X11/Xproto.h> and
similar headers for each extension requestCode uint8_t Request number of X
request or Extension requestName string Name of X request or Extension
requestLength uint16_t Length of X request sequenceNumber uint32_t Number of X
request in in this connection

This script simply increments a counter for each different request made, and
when you exit the script (such as by hitting ControlC ) prints the counts. #!/
usr/sbin/dtrace -s Xserver*:::request-start { @counts[copyinstr(arg0)] = count
(); } The output from a short run may appear as: QueryPointer 1 CreatePixmap 2
FreePixmap 2 PutImage 2 ChangeGC 10 CopyArea 10 CreateGC 14 FreeGC 14 RENDER 28
SetClipRectangles 40 This can be rewritten slightly to cache the string
containing the name of the request since it will be reused many times, instead
of copying it over and over from the kernel: #!/usr/sbin/dtrace -s string
Xrequest[uintptr_t]; Xserver*:::request-start /Xrequest[arg0] == ""/ { Xrequest
[arg0] = copyinstr(arg0); } Xserver*:::request-start { @counts[Xrequest[arg0]]
= count(); } This script records the CPU time used between the probes at the
start and end of each request and aggregates it per request type. #!/usr/sbin/
dtrace -s Xserver*:::request-start { reqstart = vtimestamp; }
Xserver*:::request-done { @times[copyinstr(arg0)] = avg(vtimestamp - reqstart);
} The output from a sample run might look like: ChangeGC 889 MapWindow 907
SetClipRectangles 1319 PolyPoint 1413 PolySegment 1434 PolyRectangle 1828
FreeCursor 1895 FreeGC 1950 CreateGC 2244 FreePixmap 2246 GetInputFocus 2249
TranslateCoords 8508 QueryTree 8846 GetGeometry 9948 CreatePixmap 12111
AllowEvents 14090 GrabServer 14791 MIT-SCREEN-SAVER 16747 ConfigureWindow 22917
SetInputFocus 28521 PutImage 240841 This script simply prints information about
each client that connects or disconnects from the server while it is running.
Since the provider is specified as Xserver$1 instead of Xserver* like previous
examples, it won't monitor all Xserver processes running on the machine, but
instead expects the process id of the X server to monitor to be specified as
the argument to the script. #!/usr/sbin/dtrace -s Xserver$1:::client-connect {
printf("** Client Connect: id %d\n", arg0); } Xserver$1:::client-auth { printf
("** Client auth'ed: id %d => %s pid %d\n", arg0, copyinstr(arg1), arg2); }
Xserver$1:::client-disconnect { printf("** Client Disconnect: id %d\n", arg0);
} A sample run: # ./foo.d 5790 dtrace: script './foo.d' matched 4 probes CPU ID
FUNCTION:NAME 0 15774 CloseDownClient:client-disconnect ** Client Disconnect:
id 65 2 15774 CloseDownClient:client-disconnect ** Client Disconnect: id 64 0
15773 EstablishNewConnections:client-connect ** Client Connect: id 64 0 15772
AuthAudit:client-auth ** Client auth'ed: id 64 => local host pid 2034 0 15773
EstablishNewConnections:client-connect ** Client Connect: id 65 0 15772
AuthAudit:client-auth ** Client auth'ed: id 65 => local host pid 2034 0 15774
CloseDownClient:client-disconnect ** Client Disconnect: id 64 This script can
be used to determine which clients are creating pixmaps in the X server,
printing information about each client as it connects to help trace it back to
the program on the other end of the X connection. #!/usr/sbin/dtrace -qs string
Xrequest[uintptr_t]; string Xrestype[uintptr_t]; Xserver$1:::request-start /
Xrequest[arg0] == ""/ { Xrequest[arg0] = copyinstr(arg0); }
Xserver$1:::resource-alloc /arg3 != 0 && Xrestype[arg3] == ""/ { Xrestype[arg3]
= copyinstr(arg3); } Xserver$1:::request-start /Xrequest[arg0] ==
"X_CreatePixmap"/ { printf("-> %s: client %d\n", Xrequest[arg0], arg3); }
Xserver$1:::request-done /Xrequest[arg0] == "X_CreatePixmap"/ { printf("<- %s:
client %d\n", Xrequest[arg0], arg3); } Xserver$1:::resource-alloc /Xrestype
[arg3] == "PIXMAP"/ { printf("** Pixmap alloc: %08x\n", arg0); }
Xserver$1:::resource-free /Xrestype[arg3] == "PIXMAP"/ { printf("** Pixmap
free: %08x\n", arg0); } Xserver$1:::client-connect { printf("** Client Connect:
id %d\n", arg0); } Xserver$1:::client-auth { printf("** Client auth'ed: id %d
=> %s pid %d\n", arg0, copyinstr(arg1), arg2); } Xserver$1:::client-disconnect
{ printf("** Client Disconnect: id %d\n", arg0); } Sample output from a run of
this script: ** Client Connect: id 17 ** Client auth'ed: id 17 => local host
pid 20273 -> X_CreatePixmap: client 17 ** Pixmap alloc: 02200009 <-
X_CreatePixmap: client 17 -> X_CreatePixmap: client 15 ** Pixmap alloc:
01e00180 <- X_CreatePixmap: client 15 -> X_CreatePixmap: client 15 ** Pixmap
alloc: 01e00181 <- X_CreatePixmap: client 15 -> X_CreatePixmap: client 14 **
Pixmap alloc: 01c004c8 <- X_CreatePixmap: client 14 ** Pixmap free: 02200009 **
Client Disconnect: id 17 ** Pixmap free: 01e00180 ** Pixmap free: 01e00181
