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Revisiting the Killer NIC, eight years on

A showdown of Killer proportions

Onboard Gigabit Ethernet: we don't think about it too much. We've had it for a long time, and for the most part, it just works. The folks behind the Killer Networking products first burst on to the scene trying to change that, and they're still at it. It's been just over eight years since we first took an in-depth look at a Killer NIC. Now that a good number of gaming-focused Z170-based boards and laptops include Gigabit Ethernet (and wireless networking) powered by Killer, it's the perfect time to do some fresh testing.

A few weeks ago, I visited the Killer Networking folks at Rivet Networks. While I was there, I got a chance to pick the brains of Killer CEO Mike Cubbage and Chief Marketing Officer Bob Grim. Cubbage is one of the co-founders of Bigfoot Networks, and he's been with the Killer Networking team from the beginning, through Qualcomm's  purchase of Bigfoot in 2011 and during the team's time as part of the Big Q. He's also responsible for taking Killer independent again with Rivet Networks.

Like Cubbage, Grim is one of the founders of Bigfoot Networks. He served as the company's vice-president of marketing and sales. In late 2007, he left Bigfoot for AMD, where he ran a number of marketing and sales teams. As of this month, though, he's made his way back to the Killer team to help with marketing and business development.

I spent my time at Rivet Networks asking lots of questions about the hardware and software that makes up Killer's current products, the team's success in getting motherboard and laptop design wins, and how the Killer products have changed since the days of the original Killer NIC. The company also gave me a demo of the Killer traffic-prioritization technology, as well as a look at DoubleShot Pro—a solution in which Killer's wired and wireless controllers work together to shuttle low-priority traffic over Wi-Fi and high-priority packets over Ethernet.

As TR's motherboard guy, I came away from the visit eager to do some in-depth testing of the Killer E2400 Gigabit Ethernet controller that we've seen on the last two Z170 boards we reviewed: the Gigabyte Z170X-Gaming 7 and the MSI Z170A Gaming M5. Our test subject in this case is the Z170X-Gaming 7. With its twin GigE interfaces—one Killer-powered and one Intel-powered—it's the perfect candidate for some side-by-side testing. But before we get to that, I'll discuss what I learned from my visit.

Killer's hardware
For those not familiar with the Killer story, here's the Cliff's Notes version. Bigfoot Networks—the company that created the Killer NIC—arrived on the scene in 2006. Bigfoot wanted to bring innovation to consumer networking with a series of gaming-focused NICs. Early Killer cards had dedicated network hardware built around a Freescale PowerPC system-on-a-chip with 64MB of dedicated memory. The cards ran a custom embedded Linux distribution.

This hardware could operate in a mode that bypassed the Windows networking stack entirely to purportedly speed up packet processing and reduce latency. Bigfoot even offered a software developer's kit that allowed end users to write their own applications for the Killer NIC. While a handful of interesting apps were produced, no killer app emerged.

Part of the problem may have been the card's price tag—$279, to be exact. Subsequent iterations of Killer hardware brought the price down to a more palatable $79, but Killer was still asking buyers to fork over money for a component most folks were used to getting for free on their motherboards. In the end, the dedicated hardware of the Killer NIC simply cost more than the onboard GigE solutions that relied on the standard combination of a controller and a PHY. That solution never led to the mass-market adoption for which Bigfoot was hoping.

The pivotal moment in the life of Killer's tech, I'm told, came about with the release of Intel's Nehalem-based Core i7 processors in 2008. Suddenly, the performance of the dedicated hardware solution could be matched by moving Killer's network processing to the host CPU. At this point, Bigfoot began turning the Killer technology into an intelligent software layer focused on traffic classification and prioritization, built on top of a network driver tweaked for low latency. Using hardware to bypass the operating system's network stack reverted to the realm of high-frequency traders.

So if the intelligence has moved back into software, what's the hardware behind current Killer NICs? Given that Bigfoot Networks was eventually acquired by Qualcomm, it should come as no surprise that Qualcomm's Atheros division provides the Gigabit Ethernet controllers that serve as the foundation for current Killer solutions.

Despite being a separate company today, Rivet Networks still maintains strong ties to Qualcomm. In fact, it's one of Qualcomm Atheros' authorized design centers. That status gives the Killer folks access to detailed parameters of the Atheros chip that they're using, so Killer's driver developers can tune the software's behavior to suit their main goal: low-latency operation. The development team can also pass ideas back to the Atheros engineers for changes or additions to the underlying Ethernet controller.

Also, the Killer Networking team is now working exclusively with motherboard and laptop makers to get design wins for their Ethernet and Wi-Fi controllers. That means we won't be seeing any new stand-alone Killer network cards. Rivet says it only plans to make one Killer product offering available at a time, so we should see the most recent E2400 controller replace the older E2200 in motherboards over the next six months or so.

Killer's software stack
So modern Killer Networking solutions put the secret sauce in the software stack. What does the recipe look like?

At the 30,000-foot view, the Killer Networking software stack—the "Killer Suite"—is made up of three components. The Killer driver sits closest to the hardware. Above that is the Killer Windows service, and atop that is the Killer Network Manager software. For those who just want to use the Killer NIC as a standard Ethernet controller without all of the Killer components, there is a driver-only package available.

First, the driver. One major difference between the Killer driver and the equivalent Qualcomm Atheros driver is the threshold each one uses for sending out a packet. Killer tells us its driver has been tweaked to minimize latency, so as soon as it gets any amount of data to send, it puts that data straight onto the wire. In contrast, a driver that doesn't prioritize latency may hold off on sending to do a couple of things. Such a driver might wait to combine multiple small payloads into a single packet if the destination is the same, or it may queue up multiple sends at a time to minimize the number of interrupts taken. Games usually send out data in 128-byte chunks or less, so Killer's driver should minimize the amount of time that game data spends in the network stack. In fact, the Killer Networking folks claim the E2400's latency performance beats the competition by up to 50% during single-application usage.

Killer's Network Manager software is based around detection, classification, and prioritization of network traffic. It automatically assigns priorities to different types of network traffic in the system. Take traffic from torrents, for instance. Those packets are high-bandwidth but latency-insensitive. We don't want this traffic to monopolize bandwidth to the detriment of latency-sensitive applications, like games and VoIP clients. Killer's default traffic priorities are assigned as follows, with priorities decreasing as you move to the right:

Games  →  real-time video & voice  →  browser traffic →  everything else

These default priorities can be augmented with custom profiles for applications of your choice using the Network Manager interface.

Killer says network traffic is classified by a combination of static rules—port X means traffic of type M—and heuristics that look at the network activity from each running process. In the case of a web browser, the currently active tab determines the priority—if you're watching something that streams video to you, like YouTube, the browser will have a higher priority than it would if you're reading this article.

Killer refines its default profiles and makes those improvements available as downloads. To update the rules and heuristics, simply click the "Download Latest App Priorities" button in the Network Settings screen of the Killer Network Manager.

The Network Settings screen also houses the one piece of required setup that the Killer software needs. You have to tell it your upstream and downstream speeds, so that it knows how much total bandwidth it has to play with. And, as shown above, if you want to disable the Killer software's Bandwidth Control functionality, you can do so from this screen.

One last feature of the Killer Network Manager that we haven't touched on yet is its built-in monitoring. Click over to the performance screen and you'll see the top five applications by total traffic, as well as stats on upload and download usage for the past two minutes.

Unfortunately, the user can't configure how many minutes of data is shown for the upload and download stats, nor can one export the data. You can reset the top five applications data using a button back in the Applications page, though.

The Killer suite of software is only available for Windows. That exclusivity isn't surprising given Killer's gaming focus. For the Linux users out there, the Killer NICs work with the existing alx Ethernet driver. Support for the latest Killer E2400 hasn't been merged upstream yet, though, so you'll have to patch the driver to add the necessary PCI ID.

Now that we've looked at Killer's full hardware and software stack, let's get to testing it.