Re: Xen, oprofile, perf, PEBS, event counters, PVHVM, PV

[Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>]

On Wed, 2013-01-16 at 11:18 -0500, Boris Ostrovsky wrote:
> On 01/15/2013 11:47 PM, Konrad Rzeszutek Wilk wrote:
> > On Tue, Jan 15, 2013 at 05:11:01PM +0000, Marcus Granado wrote:
> >> On 14/01/13 20:45, Konrad Rzeszutek Wilk wrote:
> 
> >>> And it occurs to me it could be possible be to make some inroads on making
> >>> performance monitoring easier:
> >>>
> >>>    1). fix the glaring omissions in oprofile for the new CPUs
> >>>    2). Add a register keyhandle to get some debug info.
> >>>    3). piggyback on oprofile hypercalls and insert some bridge in perf (lots
> >>>        of handwaving here). Or perhaps emulate in the Linux kernel the
> >>>        wmsrs (so xen_safe_wrmsrs) and have the pvops kernel based on the MSRs
> >>>        make the hypercalls to setup the buffers, etc.
> >>>
> >>>       3a). new hypercalls? intercept rdmsr/wrmsrs and stuff the right data
> >>>        in the initial domain? Other thoughts?
> >>>
> >>>    4). Extend perf to have '--xen' so it can also look at the xen-hypervisor
> >>>        ELF file.
> >>
> >> 5) live event reports from xenoprof/opreport, ala perf top.
> >> 6) ports of oprofile kernel modules for other oses (bsd, windows,
> >> mirage), so that these oses can be used as active participants.
> 
> (+ Suravee)
> 
> What is the status of oprofile development in general (on Linux)? I 
> don't see a whole lot of activity there, it appears to be more in 
> maintenance mode.

Linux OProfile driver is in maintenance mode.  However, the user-space tools have been converted to use 
PERF syscalls interface which allows it to support per-process (non-root) profiling (similar to PERF default mode).  

One advantage of OProfile is the large database of performance counters on various platforms.

Suravee

> I realize that doing (4) may end up being a lot of work but given much 
> more active perf development it seems to me that this should be the 
> preferred route.


> -boris