Re: Fwd: Any way to find the network usage by a process?

[Mike Mason <mmlnx at us dot ibm dot com>]

Frank Ch. Eigler wrote:
> Hi -
>
> On Thu, Oct 05, 2006 at 04:28:10PM -0700, Mike Mason wrote:
> > [...]
> > ERROR: empty aggregate near identifier 'execname' at nettop.stp:35:4
> > WARNING: Number of errors: 1, skipped probes: 0
> > Apparently using @sum on empty aggregates isn't allowed. I expected 0's to 
> > be returned. 
>
> As a judgement call, to be consistent with other extractors like @avg,
> the @sum etc. of an empty set was deemed to be undefined.
>
> > The only way to avoid the error is use @sum only if @count > 
> > 0, which makes the printf too complex in my opinion.
>
> Maybe so.  It's worth considering some syntactic sugar to express a
> undefined=>0 intent.

Actually, the following works fine and doesn't complicate it too much:

        foreach ([pid, dev] in ifpid-) {
                n_xmit = @count(ifxmit[pid, dev])
                n_recv = @count(ifrecv[pid, dev])
                printf("%5d %5d %-7s %7d %7d %7d %7d %-15s\n",
                        pid, user[pid], dev, n_xmit, n_recv,
                        n_xmit ? @sum(ifxmit[pid, dev])/1024 : 0,
                        n_recv ? @sum(ifrecv[pid, dev])/1024 : 0,
                        execname[pid])
        }

I'll update the wiki page.  Thanks for the suggestions.

- Mike