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Re: [Ltt-dev] LTTng 0.10.0-pre23 (fix)

Mathieu Desnoyers wrote:
* Mathieu Desnoyers (compudj@krystal.dyndns.org) wrote:
* Mathieu Desnoyers (compudj@krystal.dyndns.org) wrote:
Hi,

I just released lttng 0.10.0-pre22 for Linux 2.6.24-rc2, which adds
support for multiple callbacks connected to a single marker. I make
extensive use the kernel RCU mechanism so batch connexion of probes to
different markers can be done as quickly as possible, requiring to wait
for quiescent state only when necessary. It proves to be important when
connecting probes on busy systems, where waiting for ~50
synchronize_sched() could take about 1-2 minutes.

Actually this release is pre21, not pre22.


LTTng 0.10.0-pre23 fixes a bug in an inaccurate assumption that a
function pointer is always aligned on (at least) 2 bytes boundaries.
It's not on some architectures.

I tested your changes on x86_64 using multiple instances of the probe-example code. Everything seems to work fine. The code itself looks fine, too, though I'm no RCU expert. The SystemTap support for markers will have to change again since the register and unregister interfaces have changed. I also noticed the arm and disarm functions are gone. I never quite understood why those were necessary anyway.

When do you anticipate pushing multiple marker support upstream? Also, are there any upcoming changes that may change the interfaces again? It'll be nice when the interface is locked in.

Mike


Mathieu


Mathieu

--
Mathieu Desnoyers
Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F  BA06 3F25 A8FE 3BAE 9A68
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--
Mathieu Desnoyers
Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F  BA06 3F25 A8FE 3BAE 9A68
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