This is the mail archive of the mailing list for the systemtap project.

Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]
Other format: [Raw text]

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

Mike Mason wrote:
> Mathieu Desnoyers wrote:
>> * Mathieu Desnoyers ( wrote:
>>> * Mathieu Desnoyers ( 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:

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

Of course removing the '__attribute__((aligned(2)))' makes it work
correctly.  Am I missing something here?

David Smith
Red Hat
256.217.0141 (direct)
256.837.0057 (fax)

Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]