--- On Wed, 8/12/09, Pyun YongHyeon <pyu...@gmail.com> wrote:

> From: Pyun YongHyeon <pyu...@gmail.com>
> Subject: Re: nfe taskq performance issues
> To: "Peter Steele" <pste...@webmail.maxiscale.com>
> Cc: freebsd-net@freebsd.org
> Date: Wednesday, August 12, 2009, 5:35 PM
> On Thu, Jul 23, 2009 at 08:58:07AM
> -0700, Peter Steele wrote:
> > We've been hitting serious nfe taskq performance
> issues during stress
> > tests and in doing some research on the problem we
> came across this old
> > email:
> > 
> >  
> > 
> > From: Ivan Voras <ivo...@freebsd.org>
> > Date: April 28, 2009 3:53:14 AM PDT
> > To: freebsd-thre...@freebsd.org
> > Cc: freebsd-net@freebsd.org,
> freebsd-performa...@freebsd.org
> > Subject: Re: FreeBSD 7.1 taskq em performance
> > >
> > > I have been hitting some barrier with FreeBSD 7.1
> network performance.
> > I
> > > have written an application which contains two
> kernel threads that
> > takes
> > > mbufs directly from a network interface and
> forwards to another
> > network
> > > interface. This idea is to simulate different
> network environment.
> > >
> > > I have been using FreeBSD 6.4 amd64 and tested
> with an Ixia box
> > > (specialised hardware firing very high packet
> rate). The PC was a
> > Core2 2.6
> > > GHz with dual ports Intel PCIE Gigabit network
> card. It can manage up
> > to 1.2
> > > million pps.
> > >
> > > I have a higher spec PC with FreeBSD 7.1 amd64
> and Quadcore 2.3 GHz
> > and
> > > PCIE Gigabit network card. The performance can
> only achieve up to 600k
> > pps.
> > > I notice the 'taskq em0' and 'taskq em1' is solid
> 100% CPU but it is
> > not in
> > > FreeBSD 6.4. 
> > 
> >  
> > 
> > In our case we are running FreeBSD 7.0, but we are
> seeing our boxes
> > experience serious thread starvation issues as the
> nfe0 cpu percentage
> > climbs steadily while cpu idle time drops at times to
> 0 percent. This
> > email thread mentioned a patch for the em driver
> here:
> > 
> >  
> > 
> > http://people.yandex-team.ru/~wawa/ 
> > <http://people.yandex-team.ru/%7Ewawa/>
> 
> > 
> >  
> > 
> > Does anyone know if this patch will work with the nfe
> driver?
> > 
> 
> That's for em(4).
> 
> AFAIK all nfe(4) controllers lacks intelligent interrupts
> moderation so driver should be prepared to handle
> excessive
> interrupt loads. I'm not sure whether NVIDIA ethernet
> controllers
> really lacks efficient interrupt mitigation mechanism but
> it
> seems Linux also faces the same hardware problem.
> As you might know there is no publicly available data sheet
> for
> NVIDIA controllers so setting it right looks very hard to
> me.
> 

Try removing the INTR_MPSAFE flag from the bus_setup_intr() call.
The entire point of using filters is to reduce lock contention.
It might not solve the problem but its clearly an unnecessary
potential bottleneck.

Barney


  
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