Linux 2.6.31's best five features

Most of the recent improvements to the Linux kernel have been for server users. But in the latest release, Linux 2.6.31, most of the best goodies are for Linux desktop users. Here's my list of the top five improvements.

1) USB 3 Support. This is the big one. We've been connecting our devices to our PCs with USB ports instead of serial or parallel ports for some time now, and that's been good. USB 2.0 has a maximum throughput of 480Mbps (Megabits per second), which is fast — but these days, when you might want to move gigabytes of movies from one device to another, it's not fast enough.

That's why the USB vendors have been working on USB 3.0, which is almost ten times faster than USB 2. USB 3 can run at an effective throughput rate of 350MBps (Megabytes per second). USB 2.0 maxes out at about 32MBps. That's faster than the SATA hard drive you are almost certainly using in your PC. USB 3 devices, which will go by the trade name of SuperSpeed USB, will start appearing by the year's end.

What's especially interesting about Linux supporting these new devices is that Linux is actually ahead of Windows and Mac OS X in supporting these super-speed hard drives, USB-flash drives and the like. Neither Windows 7 nor Snow Leopard currently supports USB 3.

2) Improved desktop speed. Due to some recent changes in the kernel, when Linux systems started running out of memory, the kernel was set up so that PROT_EXEC pages, memory pages that usually belong to currently running foreground programs were being mishandled. Instead of being kept in the memory cache, they were being written to disk until they were needed. As anyone who's ever done system optimization knows, the last place you want frequently accessed or active desktop programs is on disk. In a worst case scenario, your performance can slow down by 1000% or more. Yuck!

But now, Linux's memory management has been improved so that currently running programs stay on top of the list of active memory pages. Technical benchmarks show that netbook users and other people who run Linux on limited memory systems can except to see a desktop that's up to 50% faster than it's been in the recent past.

3) File system performance improvements. Ext3 and its successor, Ext4, are the most popular Linux desktop file systems — but neither is a real speed demon. Recently, Linus Torvalds noted that both Ext3 and Ext4 do "ACL (Access Control List,) checks on any files not owned by the caller, and it does this for every single pathname component that it looks up." That, of course, is a performance hit.

Torvalds continued, "That obviously can be pretty expensive if the file-system isn't careful about it, especially with locking. That's doubly sad, since the common case tends to be that there are no ACL's associated with the files in question." So, Torvalds has changed it so that the default behavior is to load the ACLs without any locking.

The net result is that file system reads are now about 3% faster. That may not sound like much, but it's every file read such as when you start up a program; it adds up. People who use the Oracle originated Btrfs file system will see even better performance gains with up to 15% improvements.

4) Improved graphics support. There are a lot of minor graphic improvements in this release, but the most significant are better support for the Intel i915 and ATI Radeon graphics family. These changes make graphic drivers for both popular set of graphics devices work better in Linux.

5) Better network support. Like in graphics, the real news is in new support for specific hardware. The change that will matter to most people is that Linux now includes built-in support for Intel's new Wi-Fi 802.11 3200 hardware. 3200 devices and network cards will be available in 2010. While this version doesn't support the just-approved, high-speed 802.11n Wi-Fi standard, by the time the new network equipment is shipping, 802.11n support will be baked in.

Put all this together, and I see real improvements ahead for all Linux desktop users. Indeed, whether you want to get the most from a brand-new PC in 2010 with USB 3 and Intel 3200 networking, or from an older PC or netbook with minimal memory, Linux will be the desktop operating system of choice.

Copyright © 2009 IDG Communications, Inc.

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