Intel find itself on the stand yet again for anticompetitive behaviour. This time, the FTC has ordered Intel to modify its compiler so that optimisations are applied to all chips, in the same way.All CPUs are (not) created equal
The CPU component dispatcher's role is to feed the processor the most efficient code possible. For example, for a Pentium 3 the CPU Dispatcher will apply optimisations that will enable the program to utilise SSE, but not SSE2 or SSE3, since the CPU is not aware of such technologies. So far so good, except Intel had the fantastic idea to deliberately stunt its competition. If the compiler detects a CPU with a "GenuineIntel" flag, it applies optimizations, if not, then goodbye speedy code.
Effects on computationally-intensive applications
For Folding@Home, the speedy and efficient execution of code has long been a major recurring problem. Windows is as ever the trouble platform, though this time for different reasons. Indeed, the two main compilers used by Stanford are Visual Studio and the Intel compiler. Visual Studio offers lower performance but can produce code for virtually any CPUs. Intel's compiler works miracles on Intel CPUs... but considerably slows the code compiled for use with its CPU-producing competitors.
Stanford is therefore forced to add the Intel-specific compiler code alongside that which has traditionally been devoted to non-Intel CPUs. This makes code maintenance more difficult, and prevents the output code from reaching its optimum performance. The new Protomol core is the perfect example of this problem. It weighs in at 15MB (5MB as compressed for download); AMD is clearly behind insomuch as the level of performance is concerned; and still unsolved crashes occur on older CPUs (Athlon XP, Pentium 3, etc.).
The FTC has therefore requested that Intel stop impeding competition, and deliver a version of its compiler that restores the equality between processor brands. This news is gratifying for everyone involved, even for owners of Intel CPUs, since the cores will lighten a little.
Source: OS News
KaySL
On: 01/04/10
