Re: [Discuss-gnuradio] Gigabit Ethernet cards

[Lamar Owen]

On Friday, July 02, 2010 04:40:42 pm Marcus D. Leech wrote:
> I suspect that my GiGE NIC may be dropping packets.  It's an
> RTL8168d-type chip, according to "dmesg".
> 
> Are there known-to-be-good-with-GnuRadio NICs for PCI with low-profile
> brackets out there?  This is for
>   a 2U server platform.

As I don't have a USRP2, and probably won't be getting one any time soon, I 
can't help with that element of the question.

What I can help with is the low-profile GigE business. 

If these are 32-bit slots, and if there are other bandwidth hogs on the same 
bus (like a VGA card or hard disk controller/HBA), you simply run out of PCI 
bandwidth trying to do full-rate GigE (32-bit slots, 33MHz signalling, 133MB/s 
absolute max across the shared bus).  

My 2U personal server platform is a Supermicro dual Xeon (not the Dell 2850 
I've mentioned in relation to another project, but this is my own personal 
box), which has four complete PCI-X busses, two of which can run 64-bit cards 
in 133MHz signaled sockets, giving a max of 1066MB/s (the actual clock is 
133.333333....MHz, thus the data isn't 1064MB/s),  I have a dual Intel PRO/1000 
MT card with deep buffers, low-profile, and a 64-bit interface, sitting alone 
on one of the board's PCI-X busses.  It actually can't run at 133MHz, but can 
at 66MHz, but that's still 533MB/s data rates).  Got it on eBay for $39.95, 
NIB.  There's one on eBay now for that price; there's also a single port for 
$29.  Search for 'low profile PCI-X Intel' and those two are the only hits, as 
of 11:45A EDT, today.

The e1000 driver does have its issues, but it's been solid for me with Fedora 
13 for a few weeks now, and it was solid with CentOS 5 for months before that.

Since you said PCI, I'm assuming this isn't a PCI Express box we're talking 
about here, since that changes everything.  A single lane PCI-e slot is capable 
of 250MB/s throughput, if the chipset can keep up.  Typical server GigE cards 
for PCI-e can have two or four ports and need a four lane slot; if you have 
dual PCI-e x16 slots, use the secondary x16 slot in x4 mode.

Here's the lspci -a output for the above card:
05:01.0 Ethernet controller: Intel Corporation 82546EB Gigabit Ethernet 
Controller (Copper) (rev 01)
        Subsystem: Intel Corporation PRO/1000 MT Dual Port Server Adapter
        Flags: bus master, 66MHz, medium devsel, latency 64, IRQ 96
        Memory at e8520000 (64-bit, non-prefetchable) [size=128K]
        I/O ports at 5400 [size=64]
        Capabilities: [dc] Power Management version 2
        Capabilities: [e4] PCI-X non-bridge device
        Capabilities: [f0] MSI: Enable- Count=1/1 Maskable- 64bit+
        Kernel driver in use: e1000
        Kernel modules: e1000

05:01.1 Ethernet controller: Intel Corporation 82546EB Gigabit Ethernet 
Controller (Copper) (rev 01)
        Subsystem: Intel Corporation PRO/1000 MT Dual Port Server Adapter
        Flags: bus master, 66MHz, medium devsel, latency 64, IRQ 97
        Memory at e8540000 (64-bit, non-prefetchable) [size=128K]
        I/O ports at 5440 [size=64]
        Capabilities: [dc] Power Management version 2
        Capabilities: [e4] PCI-X non-bridge device
        Capabilities: [f0] MSI: Enable- Count=1/1 Maskable- 64bit+
        Kernel driver in use: e1000
        Kernel modules: e1000

HTH.