Re: 2.6.12 Performance problems

Danial Thom
2005-08-26T22:18:54Z

--- Danial Thom <danial_thom@yahoo.com> wrote:

>
>
> --- Ben Greear <greearb@candelatech.com> wrote:
>
> > Danial Thom wrote:
> > >
> > > --- Ben Greear <greearb@candelatech.com>
> > wrote:
> > >
> > >
> > >>Danial Thom wrote:
> > >>
> > >>
> > >>>I think the concensus is that 2.6 has made
> > >>
> > >>trade
> > >>
> > >>>offs that lower raw throughput, which is
> > what
> > >>
> > >>a
> > >>
> > >>>networking device needs. So as a router or
> > >>>network appliance, 2.6 seems less
> suitable.
> > A
> > >>
> > >>raw
> > >>
> > >>>bridging test on a 2.0Ghz operton system:
> > >>>
> > >>>FreeBSD 4.9: Drops no packets at 900K pps
> > >>>Linux 2.4.24: Starts dropping packets at
> > 350K
> > >>
> > >>pps
> > >>
> > >>>Linux 2.6.12: Starts dropping packets at
> > 100K
> > >>
> > >>pps
> > >>
> > >>I ran some quick tests using kernel 2.6.11,
> > 1ms
> > >>tick (HZ=1000), SMP kernel.
> > >>Hardware is P-IV 3.0Ghz + HT on a new
> > >>SuperMicro motherboard with 64/133Mhz
> > >>PCI-X bus. NIC is dual Intel pro/1000.
> > Kernel
> > >>is close to stock 2.6.11.
> >
> > > What GigE adapters did you use? Clearly
> every
> > > driver is going to be different. My
> > experience is
> > > that a 3.4Ghz P4 is about the performance
> of
> > a
> > > 2.0Ghz Opteron. I have to try your tuning
> > script
> > > tomorrow.
> >
> > Intel pro/1000, as I mentioned. I haven't
> > tried any other
> > NIC that comes close in performance to the
> > e1000.
> >
> > > If your test is still set up, try compiling
> > > something large while doing the test. The
> > drops
> > > go through the roof in my tests.
> >
> > Installing RH9 on the box now to try some
> > tests...
> >
> > Disk access always robs networking, in my
> > experience, so
> > I am not supprised you see bad ntwk
> performance
> > while
> > compiling.
> >
> > Ben
>
> It would be useful if there were some way to
> find
> out "what" is getting "robbed". If networking
> has
> priority, then what is keeping it from getting
> back to processing the rx interrupts?
>
> Ah, the e1000 has built-in interrupt
> moderation.
> I can't get into my lab until tomorrow
> afternoon,
> but if you get a chance try setting ITR in
> e1000_main.c to something larger, like 20K. and
> see if it makes a difference. At 200K pps that
> would cause an interrupt every 10 packets,
> which
> may allow the routine to grab back the cpu more
> often.
>
>
> Danial
>

Just FYI, setting interrupt moderation to 20,000
didn't make much difference.

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