Linux now free from Big Kernel Lock

kernelnewbies.org

12 pointskia4 comments

Well, almost:

"Summary: Linux 2.6.37 includes several SMP scalability improvements for Ext4 and XFS, an option to compile the kernel with the Big Kernel Lock disabled"

It's still used in some old drivers and more importantly for file locking, which obviously can't be used when the BKL isn't compiled in.

Wait wait, this breaks file locking? Are you sure? It isn't in the linked page, and it seems too insane.

Follow the commit link just below it:

http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6...

Quote:

The one exception is file locking, which is practically always enabled and does a 'select BKL' instead. This effectively forces CONFIG_BKL to be enabled until we have solved the fs/lockd mess and can apply the patch that removes the BKL from fs/locks.c.

This is presumably why there hasn't been a big announcement by core kernel hackers. After all, reduction in BKL use has been an ongoing effort for the last half dozen or so releases and 2.6.37 is yet another milestone but not the end of the road quite yet.

it sounds scarier than it is:

“all the critical Linux codepaths have been BKL-free for a long time”

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