Re: [PATCH][1/7] perfctr-2.7.2 for 2.6.6-mm2: core

[Andrew Morton <akpm@osdl.org>]

Mikael Pettersson <mikpe@csd.uu.se> wrote:
>
> - core driver files and kernel changes

Looks like we need six system calls if we're going to do it that way.

All that marshalling and unmarshalling code is a bit evil.  I wonder if
there's some way in which it can be flattened out.

One option would be to present all the info to userspace as a virtual
filesystem, although it would be a bit weird that the contents of the
"files" depends upon the process which reads them.

Maybe a mkdir() on that filesystem could create a directory which contains
files which contain the counters for the process which made the directory? 
The directory would need to be auto-rmdir'ed on process exit.  It's
basically the same semantics as /proc/pid.

But /proc/pid can be read by processes other than "pid".  Does the same
apply to the perfcntr instrumentation?  (Being able to read another
process's perfcntr info sounds useful.  Is it?)