DRAM Error Rates

Robin Harris (via John Siracusa):

A two-and-a-half year study of DRAM on 10s of thousands Google servers found DIMM error rates are hundreds to thousands of times higher than thought — a mean of 3,751 correctable errors per DIMM per year.

[…]

Most DIMMs don’t include ECC because it costs more. Without ECC the system doesn’t know a memory error has occurred.

Everything is fine until the data corruption means a missed memory reference or an incorrect value or a flipped bit in a file writing to disk. What you see is a “file not found” or a “file not readable” message or, worse yet, silent data corruption - or even a system crash. And nothing that says “memory error.”

Adobe’s iPhone Flash Compiler

Aditya Bansod (via John Gruber):

We created a new compiler front end that allowed LLVM to understand ActionScript 3 and used its existing ARM back end to output native ARM assembly code. We call this Ahead of Time (AOT) compilation—in contrast to the way Adobe Flash Player and Adobe AIR function on the desktop using Just in Time (JIT) compilation. Since we are able to compile ActionScript to ARM ahead of time, the application gets all the performance benefits that the JIT would offer and the license compliance of not requiring a runtime in the final application.

In other words, it’s regular compilation.