EM and TSO

[Danny Braniss]

> On 5/16/07, Thomas Hurst <tom.hurst at clara.net> wrote:
> > * Jack Vogel (jfvogel at gmail.com) wrote:
> >
> > >  I introduced a change yesterday that limited TSO to PCI Express
> > >  adapters, I did this more for avoidance rather than a bug fix, and
> > >  I'm not 100% sure its the right thing, so I thought I would poll
> > >  everyone, do you have a PCI-X adapter and are using TSO without
> > >  problems and wish to keep the support in?
> > >
> > >  If no one is then I'll just leave it as is.
> >
> > We put CURRENT on one of our Sun X4200's for some MySQL tests a few days
> > ago and haven't noticed any problems, though it's only handled a few
> > million packets so far.
> >
> > Does this change remove support or just disable it by default?
> 
> It removed it, but Andre and my own guilty conscience has convinced
> me that I should change it back, once I get an MSI/X bug that was
> discovered with the code solved there will be another delta that will
> reenable it for PCI-X again.

em0 at pci1:1:0:   class=0x020000 card=0x10118086 chip=0x10108086 rev=0x03 
hdr=0x00
    vendor     = 'Intel Corporation'
    device     = '82546EB Dual Port Gigabit Ethernet Controller (Copper)'
    class      = network
    subclass   = ethernet
    cap 01[dc] = powerspec 2  supports D0 D3  current D0
    cap 07[e4] = PCI-X 64-bit supports 133MHz, 2048 burst read, 1 split 
transaction
    cap 05[f0] = MSI supports 1 message, 64 bit 

I have been testing TSO on a SunFire X4100, and though it works, I notice
that setting it on actually reduces throughput, from an average of 55MB/s
to 24MB/s

any explanation?

danny