This is the mail archive of the
systemtap@sourceware.org
mailing list for the systemtap project.
[Bug runtime/10013] New: Support ENABLED sdt probe macro
- From: "mjw at redhat dot com" <sourceware-bugzilla at sourceware dot org>
- To: systemtap at sources dot redhat dot com
- Date: 30 Mar 2009 09:37:12 -0000
- Subject: [Bug runtime/10013] New: Support ENABLED sdt probe macro
- Reply-to: sourceware-bugzilla at sourceware dot org
Currently there is no way for a user program that uses sdt.h for stap static
dynamic probes to know whether or not a probe has been enabled at runtime. This
might be beneficial when setting up probe arguments is expensive. This is an
issue for some interpreters that have to translate function names, classes or
methods to (pointers to) strings for example. They don't want to do that extra
argument setup unless the probe is enabled at that time. TCL for example uses a
facility like that. Java hotspot currently requires being started with an extra
flag that always translates all probe arguments when enabled. This causes a
performance hit and makes those probes only available in this "special mode"
which kind of defeats the purpose of "zero-impact, always on tracing".
This would also help with dtrace emulation for sdt. Currently our dtrace python
wrapper script just outputs "#define %s_ENABLED() 1" for every dtrace emulated
probe.
The ENABLED probe macro should return 1 when the associated probe is enabled
(the uprobe/mark set in the executable/library) and 0 otherwise.
--
Summary: Support ENABLED sdt probe macro
Product: systemtap
Version: unspecified
Status: NEW
Severity: normal
Priority: P2
Component: runtime
AssignedTo: systemtap at sources dot redhat dot com
ReportedBy: mjw at redhat dot com
http://sourceware.org/bugzilla/show_bug.cgi?id=10013
------- You are receiving this mail because: -------
You are the assignee for the bug, or are watching the assignee.