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DragonFly kernel List (threaded) for 2006-11
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Re: Lockless algorithms [was Re: splxxx replacements?]

From: talon@xxxxxxxxxxxxxxxx
Date: Sat, 18 Nov 2006 10:05:36 +0000 (UTC)

Bill Huey (hui) <billh@xxxxxxxxxxxxxxxxx> wrote:
> There are patent issues and the GPL license, but this is just too powerful an
> algorithm to ignore. In many way, this brings out the ultimate in what shared
> memory system can do.

Without entering such troll subjects, the patent issue completely kills using 
RCU outside of Linux. RCU is patented IBM with special licence to use in Linux
only, as far as i remember. Due to the history of IBM  it would be suicidal
for another project to even try using it. This leaves other open source
systems in the position to use only more traditional techniques, such as fine
grained locking. And Solaris has very good SMP performance without using RCU.
Perhaps clever people can design a RCU-like system which doesn't fall under
the RCU patent, who knows? Indeed this per CPU replication of kernel data
structures is not completely foreign to the RCU idea of replicating shared
data without being the same. 

Michel Talon

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