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..
- 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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