From: compudj Date: Wed, 21 Jan 2009 22:14:53 +0000 (+0000) Subject: ust update X-Git-Tag: v0.12.20~250 X-Git-Url: https://git.lttng.org./?a=commitdiff_plain;h=ca3fb06a495dcfc02b284274d59bdef1d47e53e7;p=lttv.git ust update git-svn-id: http://ltt.polymtl.ca/svn@3239 04897980-b3bd-0310-b5e0-8ef037075253 --- diff --git a/trunk/lttv/doc/developer/ust.html b/trunk/lttv/doc/developer/ust.html new file mode 100644 index 00000000..3fb0c444 --- /dev/null +++ b/trunk/lttv/doc/developer/ust.html @@ -0,0 +1,54 @@ + + + + LTTng User-space Tracing Design + + + +

LTTng User-space Tracing Design

+ +

+A user-space application may contain static instrumentation, and be linked with +an associated runtime library, in order to produce an execution trace. User +space Tracepoints and Markers, analogous to Kernel Tracepoints and Markers, +define program locations and arguments provided. Probes may then be connected to +each Tracepoint and Marker before they are activated. The probes will typically +call LTTng user-space event writing functions. + +

+When the instrumented application starts, a pipe is opened to allow external +tracing control, asynchronous notification is requested when commands arrive in +the pipe, and a signal handler is installed for SIGIO (or a carefully chosen +chainable signal number). Every time such signal is received, the runtime +library checks for commands received on the external tracing control pipe. The +recognized commands are: + +

list the available Markers and Tracepoints; +

dynamically load a library (presumably containing probes to connect); +

connect a probe to a Tracepoint or Marker; +

activate a Tracepoint or Marker; +

initialize the tracing buffers; +

flush the tracing buffers; +

finalize the tracing buffers; + +

+The application may also spontaneously provide information to the pipe: + +

a buffer is full; +

new tracepoints or markers are appearing or disappearing, because modules are + dynamically loaded or unloaded; + +

+In addition, the tracing control application should be notified when the +application exits (to save the content of buffers if the application is +crashing). Such notification may be obtained through utrace. +

+This tracing scheme plans to use a direct function call to tracing into buffers +mapped in user-space. This should be an order of magnitude faster than the +current Dtrace implementation (c.f. +https://ltt.polymtl.ca/tracingwiki/index.php/DTrace) which uses a breakpoint to +perform both dynamic and static user-space tracing. Performance comparison of +a function call vs the int3 approach is available at +http://sourceware.org/ml/systemtap/2006-q3/msg00793.html (see "Conclusion"). + + diff --git a/trunk/lttv/doc/developer/ust.txt b/trunk/lttv/doc/developer/ust.txt deleted file mode 100644 index a379e553..00000000 --- a/trunk/lttv/doc/developer/ust.txt +++ /dev/null @@ -1,42 +0,0 @@ -LTTng User-space Tracing Design - -A user-space application may contain static instrumentation, and be linked with -an associated runtime library, in order to produce an execution trace. User -space Tracepoints and Markers, analogous to Kernel Tracepoints and Markers, -define program locations and arguments provided. Probes may then be connected to -each Tracepoint and Marker before they are activated. The probes will typically -call LTTng user-space event writing functions. - -When the instrumented application starts, a pipe is opened to allow external -tracing control, asynchronous notification is requested when commands arrive in -the pipe, and a signal handler is installed for SIGIO (or a carefully chosen -chainable signal number). Every time such signal is received, the runtime -library checks for commands received on the external tracing control pipe. The -recognized commands are: - -- list the available Markers and Tracepoints; -- dynamically load a library (presumably containing probes to connect); -- connect a probe to a Tracepoint or Marker; -- activate a Tracepoint or Marker; -- initialize the tracing buffers; -- flush the tracing buffers; -- finalize the tracing buffers; - -The application may also spontaneously provide information to the pipe: - -- a buffer is full; -- new tracepoints or markers are appearing or disappearing, because modules are - dynamically loaded or unloaded; - -In addition, the tracing control application should be notified when the -application exits (to save the content of buffers if the application is -crashing). Such notification may be obtained through utrace. - -This tracing scheme plans to use a direct function call to tracing into buffers -mapped in user-space. This should be an order of magnitude faster than the -current Dtrace implementation (c.f. -https://ltt.polymtl.ca/tracingwiki/index.php/DTrace) which uses a breakpoint to -perform both dynamic and static user-space tracing. Performance comparison of -a function call vs the int3 approach is available at -http://sourceware.org/ml/systemtap/2006-q3/msg00793.html (see "Conclusion"). -