Performance

Vol. 10 No. 6 – June 2012

Performance

LinkedIn Password Leak: Salt Their Hide

If it does not take a full second to calculate the password hash, it is too weak.

If it does not take a full second to calculate the password hash, it is too weak.

Poul-Henning Kamp

6.5 million unsalted SHA1 hashed LinkedIn passwords have appeared in the criminal underground. There are two words in that sentence that should cause LinkedIn no end of concern: "unsalted" and "SHA1."

by Poul-Henning Kamp

Articles

Extending the Semantics of Scheduling Priorities

Increasing parallelism demands new paradigms.

Application performance is directly affected by the hardware resources that the application requires, the degree to which such resources are available, and how the operating system addresses its requirements with regard to the other processes in the system. Ideally, an application would have access to all the resources it could use and be allowed to complete its work without competing with any other activity in the system. In a world of highly shared hardware resources and generalpurpose, time-share-based operating systems, however, no guarantees can be made as to how well resourced an application will be.

by Rafael Vanoni Polanczyk

OpenFlow: A Radical New Idea in Networking

An open standard that enables software-defined networking

Computer networks have historically evolved box by box, with individual network elements occupying specific ecological niches as routers, switches, load balancers, NATs (network address translations), or firewalls. Software-defined networking proposes to overturn that ecology, turning the network as a whole into a platform and the individual network elements into programmable entities. The apps running on the network platform can optimize traffic flows to take the shortest path, just as the current distributed protocols do, but they can also optimize the network to maximize link utilization, create different reachability domains for different users, or make device mobility seamless.

by Thomas A. Limoncelli

A Nice Piece of Code

Colorful metaphors and properly reusing functions

In the last installment of Kode Vicious (A System is not a Product, ACM Queue 10 (4), April 2012), I mentioned that I had recently read two pieces of code that had actually lowered, rather than raised, my blood pressure. As promised, this editions KV covers that second piece of code.

by George Neville-Neil