Hyper-Threading Performance

Intel uses Hyper-Threading (HT) as a feature for market segmentation: The desktop Core i5 processors differ from the Core i7 mainly by whether HT has been disabled, and Intel charges a significant price premium for the Core i7. Does the performance improvement of HT justify its cost? I test the performance of HT using a selection of cluster-type workloads. . . . → Read More: Hyper-Threading Performance

Linux SMT-Aware Process Scheduling

Process scheduling for multicore multithreaded (SMT or HT) systems adds a new challenge to an operating system’s process scheduler. Two threads scheduled on different cores will run faster than two threads scheduled onto different thread contexts of the same core because much of the hardware resources are shared between SMT thread contexts. This can be . . . → Read More: Linux SMT-Aware Process Scheduling

Refrigerator Power Efficiency

It has been claimed that new refrigerators use much less power than old ones. This is also the premise of The Great Refrigerator Roundup program that encourages replacement of refrigerators older than 15 years. Here is one comparison, measured over about 3 days. . . . → Read More: Refrigerator Power Efficiency

Seasonal Fuel Efficiency

It is well-known that a car’s fuel efficiency decreases during the winter months. There are many potential contributors, including increased air density causing drag, excessively rich fuel mixture from cold starts taking a long time to warm up, increased pumping losses from dense cold air intake, increased engine oil viscosity, increased rolling friction from colder . . . → Read More: Seasonal Fuel Efficiency

Core 2, Nehalem, FPGA CAD

See also: Ivy Bridge Benchmarks

Here are some FPGA CAD benchmarks across a few relatively-modern machines. The original motivation was to figure out why VPR ran much slower on a Core 2 Xeon 5160 system than a desktop-class Core 2 Quad Q9550. A secondary goal is to measure the Core i7-980X @ 4215 MHz. I . . . → Read More: Core 2, Nehalem, FPGA CAD

Compiler Performance

Sun claims their Sun Studio 12 compiler performs well on SPEC (Free Compiler Wins Nehalem Race by 2x). So I compared PHP 5.3.1 running PHPspeed 1.0 beta (using “Real World PHP Benchmark”) and xcache 1.3.0, compiled with Sun Studio 12, GCC 4.4.1, and Intel C Compiler 11.1.064.

System Mandriva 2010.0 x86_64 kernel, Core 2 . . . → Read More: Compiler Performance