Re: Announcement: Release Candidate 1 for OProfile 1.0.0

On Fri, Aug 29, 2014 at 02:30:01AM +0100, William Cohen wrote:
> On 08/28/2014 04:47 PM, Maynard Johnson wrote:
> > *Will C*, can you please try to add '#ifdef __arm__' in the same two
> > places and see if the oprofile testsuite works then. Perhaps I should
> > back out the change I made to exclude hypervisor events.  The issue is
> > that on systems where mode exclusion *is* supported, and where the
> > system is running on top of a hypervisor, doing something like 'ocount
> > -e CYCLES:0:0:1' ends up counting *both* userspace and hypervisor events
> > and the output of ocount does not separate them.  A similar issue occurs
> > with operf, but the problem is not quite so pronounced, since opreport
> > typically cannot be resolve hypervisor sample addresses symbols.
> 
> I did a git bisection and narrowed the problem patch to:
> 
> $ git bisect bad
> 3f93a3b306875ff5591149a23034fed92a0844d7 is the first bad commit
> commit 3f93a3b306875ff5591149a23034fed92a0844d7
> Author: Maynard Johnson <[email protected]>
> Date:   Thu Aug 7 15:58:23 2014 -0500
> 
>     Exclude collecting hypervisor samples for default event
>     
>     In a July 7 commit, I made the following change:
>     
>         Make sure hypervisor is excluded from ocount and operf
>     
>         Since we have no interface support in the event specification to
>         allow the user to select or de-select counting events in hypervisor,
>         and also since the output of ocount and opreport do not support the
>         concept of hypervisor, we should exclude hypervisor from counting
>         and profiling.  There's a bug in the current code such that the
>         user may or may not get hypervisor events included.  This patch
>         explicitly excludes hypervisor.
>     
>     Apparently, I neglected making the corresponding change for the default event.
>     This patch rectifies that mistake.
>     
>     Signed-off-by: Maynard Johnson <[email protected]>
> 
> One thing to note is that the tests worked on machines that had
> virtualization support.  All the x86 rhel and fedora support
> virtualization.  The working arm kernel for the cortex a15 kernel also has
> virtualization support.  The arm f20 kernel doesn't have the
> virtualization enabled.

Indeed, I'd expect the vast majority of arm64 systems to support this
feature, as well as any new 32-bit cores (including A7, A12, A15 and A17).

It's a pity that it's not easily probable...

Will

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