[ovs-discuss] Performance counters for vswitchd

[Ben Pfaff]

On Mon, Jul 07, 2014 at 08:33:50PM +0400, Andrey Korolyov wrote:
> On Mon, Jul 7, 2014 at 7:15 PM, Ben Pfaff <blp at nicira.com> wrote:
> > On Fri, Jul 04, 2014 at 09:02:40PM +0400, Andrey Korolyov wrote:
> >> On Fri, Jul 4, 2014 at 8:39 PM, Ben Pfaff <blp at nicira.com> wrote:
> >> > On Fri, Jul 04, 2014 at 02:39:18PM +0400, Andrey Korolyov wrote:
> >> >> is there any plans around to introduce built-in performance statistics
> >> >> for userspace switch process? Right now one is able to check memory
> >> >> consumption statistics and it will be quite awesome to introduce kind
> >> >> of interface for measurement of thread performance too.
> >> >
> >> > We have performance counters.  What do you want to measure?
> >>
> >> For example, total cpu utilization by workers not involving external
> >> monitoring tools. There are two cases - reactive flows, which
> >> currently have almost linear characteristic for utilization vs flow
> >> rate when adding unique flows on moderate speed (30k/s with six cores
> >> of E5 series as a ceiling), and proactive mask/asterisk flows which
> >> has sublinear characteristic even being far away from the actual
> >> ceiling. In the second case vswitchd heavily relies on decisions made
> >> inside module` heuristic, so same flow hit rate can produce very
> >> different cpu utilization for userspace vswitchd.
> >
> > I'm not sure how OVS would do a better job of that than external
> > monitoring tools.  Doing a good job would probably mean producing a time
> > series for each thread's CPU usage.  A regular log file isn't ideal for
> > that.
> 
> Ok, I see. Jiffie counting is a pidstat job, but I thought that there
> is a easier way around.

Are you talking about performance monitoring for work done in the kernel
module (e.g. from bottom halves etc.)?  I'm only talking about
userspace.  I don't know the relevant kernel performance monitoring
infrastructure and can't speak for the right way to do it.