2005/12/14, Michael Chan <[EMAIL PROTECTED]>:
> On Wed, 2005-12-14 at 17:56 +0100, Aritz Bastida wrote:
>
> > How can I find the specs for the Tulip3 NIC?
> >
> Most of the statistics counters follow the MIB definitions in the RFCs.
> There are a few that are non-standard but should be self-explanatory.
> Send me an email if you need more information on some of the counters.
>
>
Thank you for your email. But could you tell me what RFC specifically?
Is it RFC1284? The counters I am looking for are:
dma_writeq_full
rx_threshold_hit
ring_status_update
I have a dual AMD Opteron 1800MHz, which will be capturing all the
traffic in a Gigabit Ethernet segment, and analyzing the packets it
captures. It's a kind of IDS which must work under heavy network
loads. I am testing the maximum speed it can receive packets (it has
got a Broadcom Tulip3 NIC: BCM5704). For that purpose, I use another
machine to inject the packets. I do that with the "pktgen" module.
Here are the results for a sample test:
Injection machine (Dual Pentium III 866MHz):
* Number of packets: 21134488
* Packet size: 100 bytes
* Speed: 341242pps 272Mb/sec
Receive machine (Dual AMD Opteron 1800MHz ):
(There are no processes running in this machine, specifically the packet
analysis is stopped)
* rx_ucast_packets: 21134816
* rx_65_to_127_octet_packets: 21134597
* dma_writeq_full: 12919200
* rx_discards: 12947380
* rx_threshold_hit: 1549692
* ring_status_update: 1677648
So, from 21 million packets received in the NIC, the kernel can just
"capture" 8 million. I mean, the driver will only know about 8 million
of them, the other 13 will be discarded by the NIC because the rx dma
buffer is full (or that is what it seems reading the counters).
Is this throughput low? I was told that this AMD Opteron "should" be
able to receive packets with a speed of 400000pps without losses, but
that is not what it happens to me.
May be the rx DMA buffer fills up because the ksoftirqd kernel threads
have got a low priority (19) or because the packets are not processed
immediately (a softirq has to be scheduled and run, and the buffer
could fill up meanwhile).
Any comments relating to this could help.
Thank you.
Regards
Aritz
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