This is the mail archive of the
systemtap@sourceware.org
mailing list for the systemtap project.
[Bug runtime/10013] 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: 5 Apr 2009 22:22:40 -0000
- Subject: [Bug runtime/10013] Support ENABLED sdt probe macro
- References: <20090330093705.10013.mjw@redhat.com>
- Reply-to: sourceware-bugzilla at sourceware dot org
------- Additional Comments From mjw at redhat dot com 2009-04-05 22:22 -------
(In reply to comment #3)
> This optimization is the same as in the "move immediate" kernel markers.
> However, it is not a *substitute* for a trap. It is only a substitute
> for a condition evaluation.
> [...]
> You still need some way to enter the kernel.
It isn't meant as substitute of the trap. That will still be the STAP_PROBE itself.
So the idea is that when enabling a probe, you first enable the PROBE itself,
replacing the nop with a trap, then, if there is also an associated ENABLED
conditional, you replace the move to enable the code path leading to the probe.
So user code would be written as:
if (STAP_PROBE_ENABLED(myapp, mymark))
{
do_expensive_argument_setup();
STAP_PROBE(myapp, mymark, args);
}
--
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.