[ovs-dev] [PATCH] ofproto: Warn about excessive rule counts in OpenFlow tables.

[Ben Pfaff]

I'm OK with it, I'll take your word for it that it's a better approach.

Acked-by: Ben Pfaff <blp at nicira.com>

On Wed, Sep 17, 2014 at 03:04:11PM -0700, Ethan Jackson wrote:
> I think something like that would be useful.  However, once the number
> of flows gets really high, I like the idea of having something that's
> a bit more in your face.  When debugging these things, people tend to
> tail the OVS log file instead of grepping for warnings and error
> messages.  I think something that logs once a second is much more
> likely to get noticed in this situation where each doubling happens
> over the course of several hours.  In fact I'm sure if it, as even I
> didn't notice these memory log messages on a system with a million
> OpenFlow rules yesterday.
> 
> What do you think?
> Ethan
> 
> On Wed, Sep 17, 2014 at 1:42 PM, Ben Pfaff <blp at nicira.com> wrote:
> > On Wed, Sep 17, 2014 at 01:25:19PM -0700, Ethan Jackson wrote:
> >> Frequently we've run into controller bugs which result in hundreds of
> >> thousands, or even millions of rules being installed in an OpenFlow
> >> table.  This isn't something trouble-shooters naturally think of to
> >> check for, so it's nice to have a low rate warning message to hint at
> >> the potential problem.
> >>
> >> Signed-off-by: Ethan Jackson <ethan at nicira.com>
> >
> > This seems reasonable, but I find myself wondering whether something
> > more like the memory high watermark code would be useful even in
> > non-excessive situations.  In case you aren't familiar with it, that
> > code logs whenever the amount of memory OVS is using doubles relative to
> > the last reported value.  That means that you get at most a small number
> > of log messages (since you can't double the amount of memory very many
> > times before running out) but it's easy to look at the logs and spot,
> > within a factor of 2, how much memory OVS was using.