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Re: perfmon2?
- From: William Cohen <wcohen at redhat dot com>
- To: Nathan DeBardeleben <ndebard at lanl dot gov>
- Cc: "systemtap at sources dot redhat dot com" <systemtap at sources dot redhat dot com>
- Date: Tue, 20 Feb 2007 11:40:43 -0500
- Subject: Re: perfmon2?
- References: <45DB1A2F.4020301@lanl.gov>
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