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Hardware Headaches Inevitable?
JaneWalker6847 writes "Don Becker, co-founder of the Beowulf project, describes the inevitability of hardware administration headaches and warns users not to expect a silver bullet to solve these problems." From the article: "We're about to see another revolution, which is in network adapters -- that we [will] talk directly to [them] from application level. That's a massive change in how you interface with them. And that brings about a new round of device drivers completely unlike the device drivers we had 10 years ago. So, that part of the world isn't going to stabilize anytime soon."
What they're likely talking about is technology like Chimney, which, barring lawsuits, will be coming out in or around the time of Windows Vista. Effectively, instead of the TCP/IP stack coming from the OS and running on the main processor, the network card will have a processor and memory and run the TCP/IP stack there. This increases efficiency and reduces reduces latency because the main CPU doesn't have to get involved as much. In the future we will probably see things like SSL encryption being performed on the card as well.
What happens now (on windows) is that applications talk to winsock. Winsock sends the data to kernel mode code including tcpip.sys. From there, it ends up in ndis.sys and then the driver for your network card before being sent to the card.
What this new thing means is that applications send the data to winsock which hands it directly to a new kind of network card/driver which takes the data and header info and creates the TCP/UDP and IP packets on the card itself in card firmware. From there, the card wraps it up in the lower level protocols and then puts it out over the wire (or air if its wireless)
Hmm... Do I smell WinModem?
I'm not sure what that smell is, but its familiar.
Yes, TCP/IP offloaders, crypto offloaders, physics offloaders, FFT offloaders, have all existed. The only accepted offloader that has succeeded is the GPU, and that is because it was subsidized by the high end graphics people and people with game addictions. The cost/benefit of the other offloaders has not proven itself. Especially when you consider the rate of increase of the CPU speeds and the bottleneck of getting the data to the offloaded chip and back again. The Linux kernel mailinglist has been pretty much anti TCP/IP offloading because the time spent optimizing the drivers and the performance increase was often surpassed in a few months with a faster general purpose CPU and a generic driver that worked with all cards. This is also confounded when you have OS level TCP/IP stuff like ipchains or iptables that need their code in the OS and not on the card. FFT and physics offloaders have not taken off because of the cost/benefit loss when one takes into account the speed loss of getting the data onto the card and then the cost of the cache RAM to put on the card (if its ever enough), and then the time to get the data off of the card.
Now, what will make these things work?
A bus that is near or at the speed of memory bandwidth or a problem where the data does not need to go back to the host system. A GPU falls into the second half there. The display needs to know what its told, the computer does not need to know the details. TCP/IP offloaders have failed to catch on because of the price/performance benefit and their lack of ubiquity and commonality. Crypto offloaders are cool. Especially for the geek factor of having the keys stored on the card and zeroed out when tampered with. But again, the cost of writing specific drivers vs known CPU drivers for doing crypto and the rate of increase of cheap commodity CPUs over time often exceeds the cost/benefit of the crypto card.
Now, give me a fast bus and the ability to use my generic system RAM with one of these offloading cards, and things could change, but until then I expect this battle between the CPU and specific PUs to continue with no real winner.
What really worries me are the metaphors mixed in the same sentence in the summary. So we should expect headaches, but not a silver bullet to solve them? I'm just having a mild headache at the moment, and just the thought of curing it with a bullet seems... somehow not that tempting ;)
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