7.1-PRERELEASE : bad network performance (nfe0)

Luigi Rizzo rizzo at iet.unipi.it
Mon Sep 29 21:24:27 UTC 2008

On Mon, Sep 29, 2008 at 09:10:29PM +0100, Robert Watson wrote:
> On Mon, 29 Sep 2008, Arno J. Klaassen wrote:
> >However, the "request/respones" tests are awfull for my notebook (test 
> >repeated on the notebook for the sake of conviction) :
> Is it possible to rerun these tests with a 7.0 kernel of the same general 
> configuration?  That would help us determine if it's a regression between 
> 7.0 and 7.1, or perhaps a more general issue between 6.x and 7.x.  I 
> wouldn't reject a hardware, driver, or general stack issue at this point as 
> things are still fairly unclear.  If it's definitely between 7.0 and 7.1 
> that the problem arises, trying a series of kernels spaced at, say, one 
> month intervals in that period would be quite helpful in narrowing down the 
> source.

two things:
+ the 'nfe' driver is not in 6.x so i wonder how these numbers were
  derived in 6.x -- perhaps using a backport, or using the nve driver
  instead ? In any case we cannot easily compare 6.x and 7.x behaviour
  with nfe.

+ with the nfe driver and the MCP67 chipset i have found a tendency of
  the card to stall at high data rates and with some system load (e.g.
  massive scp while some X applications is spinning). This was completely
  repeatable and caused the network card to become deaf (it could transmit
  though) and it required an ifconfig down/up to come back to life,
  watchdogs and timeouts did not fix it.

  Additionally i have found some bug in the polling implementation
  which may or may not relate to more generic interrupt handling.
  This was described in a thread in april.
  A patch to address the stalls is at
  (i have been running this on my home pc since late april)
  A related patch changes slightly the implementation of polling:

At the time when i raised the problem on the mailing list apparently
others were not seeing the problem so i did not pursue the integration
in the system - but if this is a significant problem in 7.1R then
it is worth a try.


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