perfmon2?

perfmon2?

[Nathan DeBardeleben]

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.

-- 
-- Nathan
Correspondence
---------------------------------------------------------------------
Nathan DeBardeleben, Ph.D.
Los Alamos National Laboratory
Parallel Tools Team
High Performance Computing Environments (HPC-4)
phone: 505-667-3428
email: ndebard@lanl.gov
---------------------------------------------------------------------

Re: 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

Re: perfmon2?

[Frank Ch. Eigler]

Nathan DeBardeleben <ndebard@lanl.gov> writes:

> I was told recently that kprobes will be going away in about a year
> in the kernel to be replaced by perfmon2.  [...]

Where did you hear that?  The two technologies aren't substitutes
for one another.

- FChE

Re: perfmon2?

[Nathan DeBardeleben]

Yeah so that's what I thought but it came up in a conversation and I 
wanted to go to "the source" to get my information before stating what I 
thought was true.  My understanding of perfmon2 was such that I didn't 
think it could do what I currently do w/ kernel probes.

Sorry to derail the conversation, just wanted to get an answer from the 
horse's mouth.

-- Nathan
Correspondence
---------------------------------------------------------------------
Nathan DeBardeleben, Ph.D.
Los Alamos National Laboratory
Parallel Tools Team
High Performance Computing Environments (HPC-4)
phone: 505-667-3428
email: ndebard@lanl.gov
---------------------------------------------------------------------



Frank Ch. Eigler wrote:
> Nathan DeBardeleben <ndebard@lanl.gov> writes:
>
>   
>> I was told recently that kprobes will be going away in about a year
>> in the kernel to be replaced by perfmon2.  [...]
>>     
>
> Where did you hear that?  The two technologies aren't substitutes
> for one another.
>
> - FChE
>
>   

Re: perfmon2?

[Frank Ch. Eigler]

Hi -

> [...] Sorry to derail the conversation, just wanted to get an answer
> from the horse's mouth.

Hey, whom are you calling a horse?

- FChE