Re: [Xen-devel] [PATCH] xentop: Dynamically expand some columns

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Thu, 2014-10-02 at 13:05 -0400, Konrad Rzeszutek Wilk wrote:
> On Thu, Oct 02, 2014 at 10:25:41AM -0600, Charles Arnold wrote:
> > >>> On 10/2/2014 at 10:10 AM, Andrew Cooper <andrew.cooper3@xxxxxxxxxx> 
> > >>> wrote: 
> > > On 02/10/14 16:58, Charles Arnold wrote:
> > >> Allow certain xentop columns to automatically expand as the amount
> > >> of data reported gets larger.  The columns allowed to expand are:
> > >>
> > >> NETTX(k), NETRX(k), VBD_RD, VBD_WR, VBD_RSECT, VBD_WSECT
> > >>
> > >> Author: Markus Hauschild <Markus.Hauschild@xxxxxxxxxxxxxxxxxxxx>
> > >> Signed-off-by: Charles Arnold <carnold@xxxxxxxx>
> > > 
> > > In principle, very nice.  (I have wanted to see about doing this for a
> > > while now, but very far down the todo list)
> > > 
> > > How about the NAME field? 9 characters isn't enough for some people.
> > 
> > Sure, and any others that might need it.  But what to do about the '-f' flag
> > which says show me the full VM name but the flag doesn't adjust the entire
> > column.  By automatically showing the full name and adjusting the column
> > appropriately it makes this flag pointless (which I'm ok with). 
> 
> Perhaps this functionality should be under that option?
> 
> I am a bit hesistant about this as there are some users of xentop that
> use it for their monitoring. What I can't remember is if they use the
> batched mode or not - and if they scan for specific strings (and length).
> 
> This would (I think?) throw a wrench in that?

IMHO people who are parsing the output of tools such as this ought to be
prepared to deal with occasional changes in the precise content of the
output across Xen releases.

If they aren't happy with that then they should file wishlist bugs (or
better: patches) asking for an extensible/machine-readable format to be
output upon request, or for libxenstat to be exposed and made API
stable, or some other functionality which solves their need.

Otherwise we find ourselves in a position where useful patches like
Charles' and similar patches which add genuinely useful output for human
readers can never be accepted.

Ian.



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