On Nov 6, 2003, at 10:26 AM, Jack L. Stone wrote:
This "price advice" then implies that if Realtek simply raised their
prices, the card would be just fine...??

No. The price advice implies that a NIC that is worth $5 is probably not as good as a NIC which is worth $50. If Realtek raised their prices, their cards would become overpriced "cheapo" NICs rather than cheap "cheapo" NICs. :-)

One should not just go by "expensive", but do some research not just based
on that "easy" benchmark. The "cheapo" measurement is very misleading
considering some cards may just be "on sale" and are fine cards. ...or just
because they use the rlx driver....

Speaking of which, /usr/src/sys/pci/rl.c provides some very specific technical details as to the design flaws with this chipset family:

* The RealTek 8139 PCI NIC redefines the meaning of 'low end.' This is
* probably the worst PCI ethernet controller ever made, with the possible
* exception of the FEAST chip made by SMC. The 8139 supports bus-master
* DMA, but it has a terrible interface that nullifies any performance
* gains that bus-master DMA usually offers.
* For transmission, the chip offers a series of four TX descriptor
* registers. Each transmit frame must be in a contiguous buffer, aligned
* on a longword (32-bit) boundary. This means we almost always have to
* do mbuf copies in order to transmit a frame, except in the unlikely
* case where a) the packet fits into a single mbuf, and b) the packet
* is 32-bit aligned within the mbuf's data area. The presence of only
* four descriptor registers means that we can never have more than four
* packets queued for transmission at any one time.
* Reception is not much better. The driver has to allocate a single large
* buffer area (up to 64K in size) into which the chip will DMA received
* frames. Because we don't know where within this region received packets
* will begin or end, we have no choice but to copy data from the buffer
* area into mbufs in order to pass the packets up to the higher protocol
* levels.
* It's impossible given this rotten design to really achieve decent
* performance at 100Mbps, unless you happen to have a 400Mhz PII or
* some equally overmuscled CPU to drive it.


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