From the 'Unlocking Linux' files:

The first release candidate for the upcoming Linux 2.6.38 kernel is now out and it could further improve Linux performance.

With 2.6.37, the Big Kernel Lock (BKL) was removed, but apparently there is at least one more big global lock that needed to come out. In 2.6.38 there is a new RCU (Read/Copy/Update)-based path name lookup.



"It's some seriously good stuff, and gets rid of

the last main global lock that really tends to hurt some kernel loads," Linus Torvalds commented about the RCU lookup.

Torvalds added that the new lookup improves kernel performance by as much as 30 to 50 percent in some cases.