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| -rw-r--r-- | stapprobes.5.in | 36 |
1 files changed, 36 insertions, 0 deletions
diff --git a/stapprobes.5.in b/stapprobes.5.in index 0854be53..0daeb973 100644 --- a/stapprobes.5.in +++ b/stapprobes.5.in @@ -548,6 +548,42 @@ The marker format string associated with a marker is available in And also the marker name string is avalable in .BR $name . +.SS TRACEPOINTS + +This family of probe points hooks up to static probing tracepoints +inserted into the kernel or modules. As with markers, these +tracepoints are special macro calls inserted by kernel developers to +make probing faster and more reliable than with DWARF-based probes, +and DWARF debugging information is not required to probe tracepoints. +Tracepoints have an extra advantage of more strongly-typed parameters +than markers. + +Tracepoint probes begin with +.BR kernel . +The next part names the tracepoint itself: +.BR trace("name") . +The tracepoint name string, which may contain the usual wildcard +characters, is matched against the names defined by the kernel +developers in the tracepoint header files. + +The handler associated with a tracepoint-based probe may read the +optional parameters specified at the macro call site. These are +named according to the declaration by the tracepoint author. For +example, the tracepoint probe +.BR kernel.trace("sched_switch") +provides the parameters +.BR $rq ", " $prev ", and " $next . +If the parameter is a complex type, as in a struct pointer, then a +script can access fields with the same syntax as DWARF $target +variables. Also, tracepoint parameters cannot be modified, but in +guru-mode a script may modify fields of parameters. + +The name of the tracepoint is available in +.BR $$name , +and a string of name=value pairs for all parameters of the tracepoint +is available in +.BR $$vars . + .SS PERFORMANCE MONITORING HARDWARE The perfmon family of probe points is used to access the performance |