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

* Mathieu Desnoyers ([email protected]) wrote:
> * David Smith ([email protected]) wrote:
> > Mike Mason wrote:
> > > Mathieu Desnoyers wrote:
> > >> * Mathieu Desnoyers ([email protected]) wrote:
> > >>> * Mathieu Desnoyers ([email protected]) 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.
> > 
> > Systemtap has been updated to work with latest LTTNG patch
> > patch-2.6.24-rc2-lttng-0.10-pre23.tar.bz2, with one exception.
> > 
> > Mathieu, in samples/markers/probe_example.c, you've got:
> > 
> > ===
> > void
> > probe_subsystem_eventb(void *probe_data, void *call_data,
> > 	const char *format, va_list *args) __attribute__((aligned(2)));
> > ===
> > 
> > However, when I try to compile that (on fedora 7) I get:
> > 
> > ===
> > probe-example.c:25: error: alignment may not be specified for
> > ‘probe_subsystem_eventb’
> > ===
> > 
> > Of course removing the '__attribute__((aligned(2)))' makes it work
> > correctly.  Am I missing something here?
> > 
> 
> wooops! that's a leftover from a test.. it's fixed now in LTTng
> 0.10.0-pre27.
> 

pre28 is out, mainly contains changes to the instrumentation support
menu removal patch.

> Thanks!
> 
> Mathieu
> 
> 
> 
> 
> > -- 
> > David Smith
> > [email protected]
> > Red Hat
> > http://www.redhat.com
> > 256.217.0141 (direct)
> > 256.837.0057 (fax)
> > 
> 
> -- 
> 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