RE: proc.psinfo.wchan_s broken?

[Ken McDonell <kenj@xxxxxxxxxxxxxxxx>]

On Thu, 2008-09-04 at 07:09 -0700, Siekas, Greg wrote:
> Nathan,
> 
...
> 
> Is proc.psinfo.wchan  also broken for newer kernels?
> 
> Is there a list somewhere that indicates which metrics do and don't work
> for various operating systems and kernels?

In general there should not need to be any such list ... the PCP agents
should be maintained in such a way that if a specific metric is not
available on a particular platform, the agent should return
PM_ERR_APPVERSION which was designed into the PCP protocols for just
this situation.

So the metacode should read like

if kernel_version == 2.6.18
        use method A
elif kernel_version < 2.6.18 && kernel_version >= 2.6.0
        use method B
else
        return PM_ERR_APPVERSION

Unfortunately, this style has not be rigorously followed by the
generations of PMDA maintainers over many years, so this works in some
places, and not elsewhere.