perfmon2?

[William Cohen]

Nathan DeBardeleben wrote:
> I was told recently that kprobes will be going away in about a year in 
> the kernel to be replaced by perfmon2.  I have no idea if this 
> information is accurate but if it is, will there be an effort to port 
> SystemTap to it?
> 
> Thanks.  Sorry for rumors if that's what they are.

Perfmon2 provides access to the performance monitoring hardware on the 
processors. It doesn't have an equivalent mechanism to kprobes. Besides the 
Perfmon2 patches needs to be in the upstream kernel; they are not in yet.

Perfmon2 provides its interfaces only to userspace through systemcalls. 
Systemtap probes work in kernel space, and need a kernel API. There was a KAPI 
proposed and implement, but that is not in the current Perfmon2 patch set.

There is an open SystemTap bugzilla to implement support for performance 
monitoring hardware:

http://sources.redhat.com/bugzilla/show_bug.cgi?id=909


-Will