Performance Intel Pro 1000 MT (PWLA8490MT)

Bosko Milekic bmilekic at technokratis.com
Tue Apr 19 14:46:47 PDT 2005


  My experience with 6.0-CURRENT has been that I am able to push at
  least about 400kpps INTO THE KERNEL from a gigE em card on its own
  64-bit PCI-X 133MHz bus (i.e., the bus is uncontested) and that's
  basically out of the box GENERIC on a dual-CPU box with HTT disabled
  and no debugging options, with small 50-60 byte UDP packets.

  I haven't measured how many I can push THROUGH to a second card and
  forward.  That will probably reduce numbers.

  My tests were done without polling so with very high interrupt load
  and that also sucks when you have a high-traffic scenario.

  But still, way better than your numbers.

  Also, make sure you are not bottlenecking on the sender-side.  e.g.,
  make sure that your sender can actually push out more PPS than what
  you appear to be bottlenecking on in the router.

-Bosko

On Wed, Apr 20, 2005 at 12:12:00AM +0300, Petri Helenius wrote:
> Eivind Hestnes wrote:
> 
> >It's correct that the card is plugged into a 32-bit 33 Mhz PCI slot. 
> >If i'm not wrong, 33 Mhz PCI slots has a peak transfer rate of 133 
> >MByte/s. However, when pulling 180 mbit/s without the polling enabled 
> >the system is very little responsive due to the interrupt load.  I'll 
> >try to increase the polling frequency too see if this increases the 
> >bandwidth with polling enabled.. Thanks for the advice btw..
> >
> There is something "interesting" going on in the em driver but I haven't 
> had the time to profile it properly and Intel has been less than 
> forthcoming with the specification which makes it more challenging to 
> try to optimize the driver further.
> 
> Pete
> 
> >- E.
> >
> >Jon Noack wrote:
> >
> >>On 4/19/2005 1:32 PM, Eivind Hestnes wrote:
> >>
> >>>I have an Intel Pro 1000 MT (PWLA8490MT) NIC (em(4) driver 1.7.35) 
> >>>installed
> >>>in a Pentium III 500 Mhz with 512 MB RAM (100 Mhz) running FreeBSD 
> >>>5.4-RC3.
> >>>The machine is routing traffic between multiple VLANs. Recently I did a
> >>>benchmark with/without device polling enabled. Without device 
> >>>polling I was
> >>>able to transfer roughly 180 Mbit/s. The router however was 
> >>>suffering when
> >>>doing this benchmark. Interrupt load was peaking 100% - overall the 
> >>>system
> >>>itself was quite unusable (_very_ high system load). With device 
> >>>polling
> >>>enabled the interrupt kept stable around 40-50% and max transfer 
> >>>rate was
> >>>nearly 70 Mbit/s. Not very scientific tests, but it gave me a pin 
> >>>point.
> >>
> >>
> >>
> >>The card is plugged into a 32-bit PCI slot, correct?  If so, 180 
> >>Mbit/s is decent.  I have a gigabit LAN at home using Pro 1000 MTs 
> >>(in 32-bit PCI slots) and get NFS transfers maxing out around 23 
> >>MB/s, which is ~180 Mbit/s.  Gigabit performance with 32-bit cards is 
> >>atrocious.  It reminds me of the old 100 Mbit/s ISA cards...
> >>
> >>><snip>
> >>>
> >>>HZ set to 1000 as recommended in README for the em(4) driver. Driver 
> >>>is of
> >>>cource compiled into kernel.
> >>
> >>
> >>
> >>You'll need HZ set to more than 1000 for gigabit; bump it up to at 
> >>least 2000.  That should increase polling throughput a lot.  I'm not 
> >>sure about other polling parameters, however.
> >>
> >>Jon
> >
> >
> >
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> 
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-- 
Bosko Milekic
bmilekic at technokratis.com
bmilekic at FreeBSD.org


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