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Original author: 
Todd Hoff

Now that we have the C10K concurrent connection problem licked, how do we level up and support 10 million concurrent connections? Impossible you say. Nope, systems right now are delivering 10 million concurrent connections using techniques that are as radical as they may be unfamiliar.

To learn how it’s done we turn to Robert Graham, CEO of Errata Security, and his absolutely fantastic talk at Shmoocon 2013 called C10M Defending The Internet At Scale.

Robert has a brilliant way of framing the problem that I’ve never heard of before. He starts with a little bit of history, relating how Unix wasn’t originally designed to be a general server OS, it was designed to be a control system for a telephone network. It was the telephone network that actually transported the data so there was a clean separation between the control plane and the data plane. The problem is we now use Unix servers as part of the data plane, which we shouldn’t do at all. If we were designing a kernel for handling one application per server we would design it very differently than for a multi-user kernel. 

Which is why he says the key is to understand:

  • The kernel isn’t the solution. The kernel is the problem.

Which means:

  • Don’t let the kernel do all the heavy lifting. Take packet handling, memory management, and processor scheduling out of the kernel and put it into the application, where it can be done efficiently. Let Linux handle the control plane and let the the application handle the data plane.

The result will be a system that can handle 10 million concurrent connections with 200 clock cycles for packet handling and 1400 hundred clock cycles for application logic. As a main memory access costs 300 clock cycles it’s key to design in way that minimizes code and cache misses.

With a data plane oriented system you can process 10 million packets per second. With a control plane oriented system you only get 1 million packets per second.

If this seems extreme keep in mind the old saying: scalability is specialization. To do something great you can’t outsource performance to the OS. You have to do it yourself.

Now, let’s learn how Robert creates a system capable of handling 10 million concurrent connections...

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Bradley Manning.

Wikimedia Commons

Over the course of two hours in a military courtroom today, Bradley Manning explained why—and in precise detail, how—he sent WikiLeaks confidential diplomatic cables and "war logs." Bradley's 35-page statement, read over the course of a few hours this afternoon, followed the news that he had pleaded guilty to 10 lesser counts among the many charges against him. The admissions were not part of a plea bargain; Manning still faces trial in June on the most serious charges, such as "aiding the enemy."

The Guardian's Ed Pilkington sets the scene:

Manning was flanked by his civilian lawyer, David Coombs, on one side and two military defence lawyers on the other. Wearing full uniform, the soldier read out the document at high speed, occasionally stumbling over the words and at other points laughing at his own comments.

The American people had the right to know "the true costs of war," Manning said in court today today. He continued:

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Another year has come and gone and with it hundreds of thousands of images have recorded the world's evolving history; moments in individual lives; the weather and it's affects on the planet; acts of humanity and tragedies brought by man and by nature. The following is a compilation - not meant to be comprehensive in any way - of images from the first 4 months of 2012. Parts II and III to follow this week. -- Paula Nelson ( 64 photos total)
Fireworks light up the skyline and Big Ben just after midnight, January 1, 2012 in London, England. Thousands of people lined the banks of the River Thames in central London to ring in the New Year with a spectacular fireworks display. (Dan Kitwood/Getty Images)

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US and NATO forces continue to train the Afghan troops in advance of the handover of the country's security in 2014. The US-led war in Afghanistan has cost the lives of around 3,000 US and allied troops, seen thousands of Afghans killed and cost hundreds of billions of dollars. We check in on our soldiers for May (and a little bit of June 2012.) -- Paula Nelson (45 photos total)
A female US marine and members of USN Hospital Corpsman from the 1st battalion 7th Marines Regiment walk at FOB (Forward Operating Base) Jackson also known as Sabit Khadam in Sangin, Helmand Province, June 7, 2012. The US-led war in Afghanistan has cost the lives of around 3,000 U.S. and allied troops, seen thousands of Afghans killed and cost hundreds of billions of dollars. (Adek Berryakek Berry/AFP/GettyImages)

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A park ranger stands at the site of a new eruption in Virunga National Park near Goma, on November 24, 2011. Almost three weeks after a fissure opened amidst dense flat forest, the Democratic Republic of Congo’s Virunga National Park has seen an increasing number of tourists seeking to be guided on treks to witness [...]

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Libyan citizens took over Tripoli's main square on Sunday night, as rebel forces claimed to have taken control of much of the capital, and captured two of Muammar Qaddafi's sons. Rebel gains in the past several days brought them to the outskirts of Tripoli, and they practically sped into neighborhoods of the city on Sunday, facing minimal resistance. Qaddafi remains defiant, if unseen, issuing radio statements urging residents of Tripoli to rise up against the rebels. Even as celebrations took place in Benghazi and parts of Tripoli, fighting continues, and Muammar Qaddafi remains nominally in power, even though he appears to have effectively lost much of his control. Also see earlier entries: DIY Weapons of the Libyan Rebels, and Three Months of Civil War in Libya. [44 photos]

People celebrate the capture in Tripoli of Muammar Qaddafi's son and one-time heir apparent, Seif al-Islam, at the rebel-held town of Benghazi, Libya, early Monday, on August 22, 2011. Libyan rebels raced into Tripoli in a lightning advance Sunday that met little resistance as Muammar Qaddafi's defenders melted away and his 40-year rule appeared to rapidly crumble. The euphoric fighters celebrated with residents of the capital in the city's main square, the symbolic heart of the regime. (AP Photo/Alexandre Meneghini)

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