Linux Journal has published a two-part article on Linux kernel 2.6 and its benefit to embedded systems. Author Aseem R. Deshpande first outlines OS performance characteristics required for embedded use, and then shows how new kernel features and capabilities deliver most required features, while still leaving a few areas where traditional RTOSes remain unthreatened.

According to Deshpande, real-time performance is a key requirement for embedded systems, along with ability to run on inexpensive hardware. Reliability and high performance under high load are additional considerations, as is graceful crash recovery, he says.

Linux meets most of these requirements, according to Deshpande, because:

• The new 0(1) scheduler, unlike the old scheduler, runs in a predictable amount of time, whether there are only a few or many tasks in the queue.
• New synchronization primitives improve how the kernel avoids and resolves hardware contention.
• Improved threading and native POSIX threads library support bring a claimed eight-fold improvement to thread handling.
• Subarchitecture formalization makes porting to new architectures and custom hardware easier by better separating operating system components to reduce unintended consequences of modifications to them.
• uClinux support in the 2.6 kernel supports a number of inexpensive, MMU-less processors popular in embedded designs.
• Audio and multimedia improvements include the addition of Advanced Linux Sound Architecture (ALSA) and Video 4 Linux (V4L) drivers.
• USB device-side support has been added to existing USB host support, along with support for USB 2.0, bringing 40-fold performance increases.
• Wireless devices improvements have brought excellent Bluetooth support for both lossy and lossless protocols. Short-range device support (as for 802.11) has been unified. IrDA has been improved with power management. And support for long-range devices such as AX.25 over amateur radio has been added.
• Human Interface Devices (HID) support has been modularized to better support headless and keyboardless devices, and touchscreen support has been added.
• Large systems are better supported through NUMA (Non-Uniform Memory Access)
• 64-bit support now includes Opteron as well as Itanium, and a number of other advances.
• Software and networking advances include IPsec support, multicasting support, Logical Link Support for better IPX, Token Ring, and AppleTalk support, VLAN support, multi-connection NAT, and more.
• Network filesystem improvements bring experimental support for NFSv4 and support for CODA, AFS, and InterMezzo.

Read the two-part Linux Journal series here:

Part 1

Part 2

 
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