On Fri, Sep 23, 2011 at 08:53:55PM +0900, Masami Hiramatsu wrote:

(2011/09/21 5:53), Stefan Hajnoczi wrote:

quoted

On Tue, Sep 20, 2011 at 02:12:25PM -0400, Christoph Hellwig wrote:

quoted

On Tue, Sep 20, 2011 at 06:13:10PM +0100, Stefan Hajnoczi wrote:

But this should be solvable so it would be possible to use perf-probe(1)
on a std.h-enabled binary.  Some distros already ship such binaries!

I'm not sure that we should stick on the current implementation
of the sdt.h. I think we'd better modify the sdt.h to replace
such semaphores with checking whether the tracepoint is changed from nop.

I like this option.  The only implication is that all userspace tracing
needs to go through uprobes if we want to support multiple consumers
tracing the same address.

Or, we can introduce an add-hoc ptrace code to perftools for modifying
those semaphores. However, this means that user always has to use
perf to trace applications, and it's hard to trace multiple applications
at a time (can we attach all of them?)...

I don't think perf needs to stay attached to the processes.  It just
needs to increment the semaphores on startup and decrement them on
shutdown.

Are you going to attempt either of these implementations?

Stefan

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>