Re: 2.6.12 Performance problems

[Ben Greear]

Danial Thom wrote:
> --- Ben Greear <greearb@xxxxxxxxxxxxxxx> 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.
> >
> > I used brctl to create a bridge with the two
> > GigE adapters in it and
> > used pktgen to stream traffic through it
> > (250kpps in one direction, 1kpps in
> > the other.)
> >
> > I see a reasonable amount of drops at 250kpps
> > (60 byte packets):
> > about 60,000,000 packets received, 20,700
> > dropped.

I get slightly worse performance on this system when running RH9
with kernel 2.4.29 (my hacks, HZ=1000, SMP).  Tried increasing
e1000 descriptors to 2048 tx and rx, but that didn't help, or at least
not much.

Will try some other tunings, but I doubt it will affect performance
enough to come close to the discrepency that you show between 2.4
and 2.6 kernels...

I tried copying a 500MB CDROM to HD on my RH9 system, and only 6kpps
of the 250kpps get through the bridge...btw.

Ben

--
Ben Greear <greearb@xxxxxxxxxxxxxxx>
Candela Technologies Inc  http://www.candelatech.com

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