I am repeating myself here (and in the same month!), so I apologize, but
it was a different thread, so in case this helps clarify the Realtek
discussion, this is an excerpt from /sys/pci/if_rl.c (the c file for the
Realtek driver by the author of the driver for FreeBSD). He actually
states that : "This is probably the worst PCI ethernet controller ever
made, with the possible exception of the FEAST chip made by SMC", so
defend the chip if you like but I think that says it all, and from a
person who knows a lot more than I do about good vs. bad network chips:
* 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
* 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.
* On the bright side, the 8139 does have a built-in PHY, although
* rather than using an MDIO serial interface like most other NICs, the
* PHY registers are directly accessible through the 8139's register
* space. The 8139 supports autonegotiation, as well as a 64-bit multicast
* The 8129 chip is an older version of the 8139 that uses an external PHY
* chip. The 8129 has a serial MDIO interface for accessing the MII where
* the 8139 lets you directly access the on-board PHY registers. We need
* to select which interface to use depending on the chip type.
Aaron with Morad wrote:
>> I have dozens of m0n0walls and full-blown servers with RealTek cards
>> and, while I *always* recommend Intel NICs, the RTL8139s that come with
>> the motherboards sometimes have actually done pretty well when hooked up
>> to internet connections, wifi APs, etc.
>> Lee Sharp wrote:
>>> From: "Aaron with Morad" <aaronc at morad dot ab dot ca>
>>>> "the Realtek cards sucks!"
>>>> Haha... I agree.
>>> While we are testifying about hardware... :-) I have at least 25
>>> Realtek cards in production on m0n0wall with no problems. They are
>>> slow, but not as slow as the internet connection. However, I am
>>> running them all in well ventilated cases, and with good power
>>> supplies. Heat and bad power supplies cause more problems than
>>> realtek nics.
> With all of this I must confess, I do have three other m0n0walls running
> Realtek NICs just fine - these other m0n0walls serve other routing purposes
> in our network. It just seems to be the two units for the ISP side of our
> business that have given me trouble (one operational and the other a
> warm-standby). These would be the heaviest used out of the bunch. I
> suppose I should have changed out the memory and CF card in the process of
> elimination but with all of the talk (before this thread) regarding the
> performance of the Realtek NICs I thought it would be easier to complain
> (haha, sorry) and change out the box for an Intel config. The units I
> pulled out will still be used, perhaps with new RAM and CF cards this time,
> and maybe somewhere less critical to start with...
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