<?xml version="1.0" encoding="ISO-8859-1"?> <!DOCTYPE article PUBLIC "-//OASIS//DTD DocBook XML V4.3//EN" "http://www.oasis-open.org/docbook/xml/4.3/docbookx.dtd" [ <!ENTITY % defs SYSTEM "/xserver/doc/xml/xserver.ent"> %defs; ]> <article id="Xserver-DTrace"> <articleinfo> <title>Xserver Provider for DTrace</title> <author> <firstname>Alan</firstname><surname>Coopersmith</surname> <affiliation> <orgname>Oracle Corporation</orgname> <orgdiv>Solaris Engineering</orgdiv> </affiliation> </author> <releaseinfo>X Server Version &xserver.version;</releaseinfo> <copyright><year>2005</year><year>2006</year><year>2007</year><year>2010</year> <holder>Oracle and/or its affiliates. All rights reserved.</holder> </copyright> <legalnotice id="copyright"> <para> Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions: </para><para> The above copyright notice and this permission notice (including the next paragraph) shall be included in all copies or substantial portions of the Software. </para><para> THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO 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. </para> </legalnotice> </articleinfo> <sect1 id="introduction"> <title>Introduction</title> <para> This page provides details on a <ulink url="http://wikis.sun.com/display/DTrace/Statically+Defined+Tracing+for+User+Applications">statically defined user application tracing provider</ulink> for the <ulink url="http://hub.opensolaris.org/bin/view/Community+Group+dtrace/">DTrace</ulink> facility in <productname>Solaris</productname> 10, <productname>MacOS X</productname> 10.5, and later releases. This provider instruments various points in the X server, to allow tracing what client applications are up to. DTrace probes may be used with <ulink url="http://sourceware.org/systemtap/">SystemTap</ulink> on GNU/Linux systems. </para> <para> 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. </para> <para> 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. </para> </sect1> <sect1 id="probes"> <title>Available probes</title> <para> Due to the way User-Defined DTrace probes work, arguments to these probes all bear undistinguished names of <parameter>arg0</parameter>, <parameter>arg1</parameter>, <parameter>arg2</parameter>, etc. These tables should help you determine what the real data is for each of the probe arguments. <table id="Probes_and_their_arguments"> <title>Probes and their arguments</title> <tgroup cols='9'> <colspec colname="probe" colwidth="2*"/> <colspec colname="desc" colwidth="3*"/> <colspec colname="arg0" colwidth="1*"/> <colspec colname="arg1" colwidth="1*"/> <colspec colname="arg2" colwidth="1*"/> <colspec colname="arg3" colwidth="1*"/> <colspec colname="arg4" colwidth="1*"/> <colspec colname="arg5" colwidth="1*"/> <colspec colname="arg6" colwidth="1*"/> <spanspec spanname="all" namest="probe" nameend="arg4"/> <thead> <row> <entry>Probe name</entry> <entry>Description</entry> <entry>arg0</entry> <entry>arg1</entry> <entry>arg2</entry> <entry>arg3</entry> <entry>arg4</entry> <entry>arg5</entry> <entry>arg6</entry> </row> </thead> <tbody> <row> <entry spanname="all" class="grouphead">Request Probes</entry> </row> <row> <entry>request-start</entry> <entry>Called just before processing each client request.</entry> <entry><parameter>requestName</parameter></entry> <entry><parameter>requestCode</parameter></entry> <entry><parameter>requestLength</parameter></entry> <entry><parameter>clientId</parameter></entry> <entry><parameter>requestBuffer</parameter></entry> <entry nameend="arg5" class="unused"/> <entry nameend="arg6" class="unused"/> </row> <row> <entry>request-done</entry> <entry>Called just after processing each client request.</entry> <entry><parameter>requestName</parameter></entry> <entry><parameter>requestCode</parameter></entry> <entry><parameter>sequenceNumber</parameter></entry> <entry><parameter>clientId</parameter></entry> <entry><parameter>resultCode</parameter></entry> <entry nameend="arg5" class="unused"/> <entry nameend="arg6" class="unused"/> </row> <row> <entry spanname="all" class="grouphead">Event Probes</entry> </row> <row> <entry>send-event</entry> <entry>Called just before send each event to a client.</entry> <entry><parameter>clientId</parameter></entry> <entry><parameter>eventCode</parameter></entry> <entry><parameter>eventBuffer</parameter></entry> <entry nameend="arg3" class="unused"/> <entry nameend="arg4" class="unused"/> <entry nameend="arg5" class="unused"/> <entry nameend="arg6" class="unused"/> </row> <row> <entry spanname="all" class="grouphead">Client Connection Probes</entry> </row> <row> <entry>client-connect</entry> <entry>Called when a new connection is opened from a client</entry> <entry><parameter>clientId</parameter></entry> <entry><parameter>clientFD</parameter></entry> <entry nameend="arg2" class="unused"/> <entry nameend="arg3" class="unused"/> <entry nameend="arg4" class="unused"/> <entry nameend="arg5" class="unused"/> <entry nameend="arg6" class="unused"/> </row> <row> <entry>client-auth</entry> <entry>Called when client authenticates (normally just after connection opened)</entry> <entry><parameter>clientId</parameter></entry> <entry><parameter>clientAddr</parameter></entry> <entry><parameter>clientPid</parameter></entry> <entry><parameter>clientZoneId</parameter></entry> <entry nameend="arg4" class="unused"/> <entry nameend="arg5" class="unused"/> <entry nameend="arg6" class="unused"/> </row> <row> <entry>client-disconnect</entry> <entry>Called when a client connection is closed</entry> <entry><parameter>clientId</parameter></entry> <entry nameend="arg1" class="unused"/> <entry nameend="arg2" class="unused"/> <entry nameend="arg3" class="unused"/> <entry nameend="arg4" class="unused"/> <entry nameend="arg5" class="unused"/> <entry nameend="arg6" class="unused"/> </row> <row> <entry spanname="all" class="grouphead">Resource Allocation Probes</entry> </row> <row> <entry>resource-alloc</entry> <entry>Called when a new resource (pixmap, gc, colormap, etc.) is allocated</entry> <entry><parameter>resourceId</parameter></entry> <entry><parameter>resourceTypeId</parameter></entry> <entry><parameter>resourceValue</parameter></entry> <entry><parameter>resourceTypeName</parameter></entry> <entry nameend="arg4" class="unused"/> <entry nameend="arg5" class="unused"/> <entry nameend="arg6" class="unused"/> </row> <row> <entry>resource-free</entry> <entry>Called when a resource is freed</entry> <entry><parameter>resourceId</parameter></entry> <entry><parameter>resourceTypeId</parameter></entry> <entry><parameter>resourceValue</parameter></entry> <entry><parameter>resourceTypeName</parameter></entry> <entry nameend="arg4" class="unused"/> <entry nameend="arg5" class="unused"/> <entry nameend="arg6" class="unused"/> </row> <row> <entry spanname="all" class="grouphead">Input API probes</entry> </row> <row> <entry>input-event</entry> <entry>Called when an input event was submitted for processing</entry> <entry><parameter>deviceid</parameter></entry> <entry><parameter>eventtype</parameter></entry> <entry><parameter>button</parameter> or <parameter>keycode</parameter> or <parameter>touchid</parameter></entry> <entry><parameter>flags</parameter></entry> <entry><parameter>nvalues</parameter></entry> <entry><parameter>mask</parameter></entry> <entry><parameter>values</parameter></entry> </row> </tbody> </tgroup> </table> </para> </sect1> <sect1 id="arguments"> <title>Data Available in Probe Arguments</title> <para> To access data in arguments of type <type>string</type>, you will need to use <ulink url="http://wikis.sun.com/display/DTrace/Actions+and+Subroutines#ActionsandSubroutines-{{copyinstr}}"><function>copyinstr()</function></ulink>. To access data buffers referenced via <type>uintptr_t</type>'s, you will need to use <ulink url="http://wikis.sun.com/display/DTrace/Actions+and+Subroutines#ActionsandSubroutines-{{copyin}}"><function>copyin()</function></ulink>. <table id="Probe_Arguments"> <title>Probe Arguments</title> <tgroup cols='3'> <colspec colname="arg" colwidth="2*"/> <colspec colname="type" colwidth="1*"/> <colspec colname="desc" colwidth="7*"/> <thead> <row> <entry>Argument name</entry> <entry>Type</entry> <entry>Description</entry> </row> </thead> <tbody> <row> <entry><parameter>clientAddr</parameter></entry> <entry><type>string</type></entry> <entry>String representing address client connected from</entry> </row> <row> <entry><parameter>clientFD</parameter></entry> <entry><type>int</type></entry> <entry>X server's file descriptor for server side of each connection</entry> </row> <row> <entry><parameter>clientId</parameter></entry> <entry><type>int</type></entry> <entry>Unique integer identifier for each connection to the X server</entry> </row> <row> <entry><parameter>clientPid</parameter></entry> <entry><type>pid_t</type></entry> <entry>Process id of client, if connection is local (from <function>getpeerucred()</function>)</entry> </row> <row> <entry><parameter>clientZoneId</parameter></entry> <entry><type>zoneid_t</type></entry> <entry>Solaris: Zone id of client, if connection is local (from <function>getpeerucred()</function>)</entry> </row> <row> <entry><parameter>eventBuffer</parameter></entry> <entry><type>uintptr_t</type></entry> <entry>Pointer to buffer containing X event - decode using structures in <<ulink url="http://cgit.freedesktop.org/xorg/proto/xproto/tree/Xproto.h"><filename class="headerfile">X11/Xproto.h</filename></ulink>> and similar headers for each extension</entry> </row> <row> <entry><parameter>eventCode</parameter></entry> <entry><type>uint8_t</type></entry> <entry>Event number of X event</entry> </row> <row> <entry><parameter>resourceId</parameter></entry> <entry><type>uint32_t</type></entry> <entry>X resource id (XID)</entry> </row> <row> <entry><parameter>resourceTypeId</parameter></entry> <entry><type>uint32_t</type></entry> <entry>Resource type id</entry> </row> <row> <entry><parameter>resourceTypeName</parameter></entry> <entry><type>string</type></entry> <entry>String representing X resource type (<literal>"PIXMAP"</literal>, etc.)</entry> </row> <row> <entry><parameter>resourceValue</parameter></entry> <entry><type>uintptr_t</type></entry> <entry>Pointer to data for X resource</entry> </row> <row> <entry><parameter>resultCode</parameter></entry> <entry><type>int</type></entry> <entry>Integer code representing result status of request</entry> </row> <row> <entry><parameter>requestBuffer</parameter></entry> <entry><type>uintptr_t</type></entry> <entry>Pointer to buffer containing X request - decode using structures in <<ulink url="http://cgit.freedesktop.org/xorg/proto/xproto/tree/Xproto.h"><filename class="headerfile">X11/Xproto.h</filename></ulink>> and similar headers for each extension</entry> </row> <row> <entry><parameter>requestCode</parameter></entry> <entry><type>uint8_t</type></entry> <entry>Request number of X request or Extension</entry> </row> <row> <entry><parameter>requestName</parameter></entry> <entry><type>string</type></entry> <entry>Name of X request or Extension</entry> </row> <row> <entry><parameter>requestLength</parameter></entry> <entry><type>uint16_t</type></entry> <entry>Length of X request</entry> </row> <row> <entry><parameter>sequenceNumber</parameter></entry> <entry><type>uint32_t</type></entry> <entry>Number of X request in in this connection</entry> </row> <row> <entry><parameter>deviceid</parameter></entry> <entry><type>int</type></entry> <entry>The device's numerical ID</entry> </row> <row> <entry><parameter>eventtype</parameter></entry> <entry><type>int</type></entry> <entry>Protocol event type</entry> </row> <row> <entry><parameter>button, keycode, touchid</parameter></entry> <entry><type>uint32_t</type></entry> <entry>The button number, keycode or touch ID</entry> </row> <row> <entry><parameter>flags</parameter></entry> <entry><type>uint32_t</type></entry> <entry>Miscellaneous event-specific server flags</entry> </row> <row> <entry><parameter>nvalues</parameter></entry> <entry><type>int8_t</type></entry> <entry>Number of bits in <parameter>mask</parameter> and number of elements in <parameter>values</parameter></entry> </row> <row> <entry><parameter>mask</parameter></entry> <entry><type>uint8_t*</type></entry> <entry>Binary mask indicating which indices in <parameter>values</parameter> contain valid data</entry> </row> <row> <entry><parameter>values</parameter></entry> <entry><type>double*</type></entry> <entry>Valuator values. Values for indices for which the <parameter>mask</parameter> is not set are undefined</entry> </row> </tbody> </tgroup> </table> </para> </sect1> <sect1 id="examples"> <title>Examples</title> <example id="Counting_requests_by_request_name"> <title>Counting requests by request name</title> <para> This script simply increments a counter for each different request made, and when you exit the script (such as by hitting <keycombo action='simul'><keycap>Control</keycap><keycap>C</keycap> </keycombo>) prints the counts. <programlisting> #!/usr/sbin/dtrace -s Xserver*:::request-start { @counts[copyinstr(arg0)] = count(); } </programlisting> The output from a short run may appear as: <screen> QueryPointer 1 CreatePixmap 2 FreePixmap 2 PutImage 2 ChangeGC 10 CopyArea 10 CreateGC 14 FreeGC 14 RENDER 28 SetClipRectangles 40 </screen> </para> <para> 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: <programlisting> #!/usr/sbin/dtrace -s string Xrequest[uintptr_t]; Xserver*:::request-start /Xrequest[arg0] == ""/ { Xrequest[arg0] = copyinstr(arg0); } Xserver*:::request-start { @counts[Xrequest[arg0]] = count(); } </programlisting> </para> </example> <example id="Get_average_CPU_time_per_request"> <title>Get average CPU time per request</title> <para>This script records the CPU time used between the probes at the start and end of each request and aggregates it per request type. <programlisting> #!/usr/sbin/dtrace -s Xserver*:::request-start { reqstart = vtimestamp; } Xserver*:::request-done { @times[copyinstr(arg0)] = avg(vtimestamp - reqstart); } </programlisting> The output from a sample run might look like: <screen> 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 </screen> </para> </example> <example id="Monitoring_clients_that_connect_and_disconnect"> <title>Monitoring clients that connect and disconnect</title> <para> 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 <code>Xserver$1</code> instead of <code>Xserver*</code> 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. <programlisting> #!/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); } </programlisting> A sample run: <screen> <prompt>#</prompt> <userinput>./foo.d 5790</userinput> <computeroutput>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 </computeroutput> </screen> </para> </example> <example id="Monitoring_clients_creating_Pixmaps"> <title>Monitoring clients creating Pixmaps</title> <para> 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. <programlisting> #!/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); } </programlisting> Sample output from a run of this script: <screen><computeroutput> ** 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 </computeroutput></screen> </para> </example> <example id="Input_API_monitoring_with_systemtap"> <title>Input API monitoring with SystemTap</title> <para> This script can be used to monitor events submitted by drivers to the server for enqueuing. Due to the integration of the input API probes, some server-enqueued events will show up too. <programlisting> # Compile+run with # stap -g xorg.stp /usr/bin/Xorg # function print_valuators:string(nvaluators:long, mask_in:long, valuators_in:long) %{ int i; unsigned char *mask = (unsigned char*)THIS->mask_in; double *valuators = (double*)THIS->valuators_in; char str[128] = {0}; char *s = str; #define BitIsSet(ptr, bit) (((unsigned char*)(ptr))[(bit)>>3] & (1 << ((bit) & 7))) s += sprintf(s, "nval: %d ::", (int)THIS->nvaluators); for (i = 0; i < THIS->nvaluators; i++) { s += sprintf(s, " %d: ", i); if (BitIsSet(mask, i)) s += sprintf(s, "%d", (int)valuators[i]); } sprintf(THIS->__retvalue, "%s", str); %} probe process(@1).mark("input__event") { deviceid = $arg1 type = $arg2 detail = $arg3 flags = $arg4 nvaluators = $arg5 str = print_valuators(nvaluators, $arg6, $arg7) printf("Event: device %d type %d detail %d flags %#x %s\n", deviceid, type, detail, flags, str); } </programlisting> Sample output from a run of this script: <screen><computeroutput> Event: device 13 type 4 detail 1 flags 0x0 nval: 0 :: Event: device 13 type 6 detail 0 flags 0xa nval: 1 :: 0: 1 Event: device 13 type 6 detail 0 flags 0xa nval: 2 :: 0: 2 1: -1 Event: device 13 type 6 detail 0 flags 0xa nval: 2 :: 0: 2 1: -1 Event: device 13 type 6 detail 0 flags 0xa nval: 2 :: 0: 4 1: -3 Event: device 13 type 6 detail 0 flags 0xa nval: 2 :: 0: 3 1: -3 Event: device 13 type 6 detail 0 flags 0xa nval: 2 :: 0: 3 1: -2 Event: device 13 type 6 detail 0 flags 0xa nval: 2 :: 0: 2 1: -2 Event: device 13 type 6 detail 0 flags 0xa nval: 2 :: 0: 2 1: -2 Event: device 13 type 6 detail 0 flags 0xa nval: 2 :: 0: 2 1: -2 Event: device 13 type 6 detail 0 flags 0xa nval: 2 :: 0: 1: -1 Event: device 13 type 6 detail 0 flags 0xa nval: 2 :: 0: 1: -1 Event: device 13 type 5 detail 1 flags 0x0 nval: 0 :: </computeroutput></screen> </para> </example> </sect1> </article>