FreeBSD 8.0 ixgbe Poor Performance

Jia-Shiun Li jiashiun at
Thu Apr 22 10:53:21 UTC 2010

On Thu, Apr 22, 2010 at 5:34 AM, Stephen Sanders
<ssanders at> wrote:
> According to pciconf, the card is a "82598EB 10 Gigabit AF Dual Port
> Network Connection".
> It looks to me like the card is plugged into a 4xPCIe slot.  I'm sure
> this means we're not going to make the 10Gbps but I would imagine that
> we should get north of 5 Gbps.

Some suggestions:

- 'pciconf -lc' too can be used to check pcie link width. Look for
pcie capability in the output.
- IIRC the kernel auto adjusts TCP window size and one does not need
to set it manually.
- Set greater MTU size than default 1500. It helps reduce CPU loading.
- Do not use file as source or destination unless you are sure disks
and I/O paths are fast enough. 10Gbe means 1000+MB/s. Only storage
beasts can handle that. BTW, is FreeBSD able to cache and buffer them
all in memory?
- Finally, use 'top' to make sure nothing is eating up all CPU cycles.


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