Re: Lockless algorithms [was Re: splxxx replacements?]

[Bill Huey (hui) <billh@xxxxxxxxxxxxxxxxx>]

On Sat, Nov 18, 2006 at 10:05:36AM +0000, talon@xxxxxxxxxxxxxxxx wrote:
> Bill Huey (hui) <billh@xxxxxxxxxxxxxxxxx> wrote:
> 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

True, but folks seem to be using it anyways. It would contaminant the BSD
license certainly.

> structures is not completely foreign to the RCU idea of replicating shared
> data without being the same. 

The semantics are different than any simple case. RCU allows for concurrent
readers on a per CPU basis. I'm sure a data replication scheme can do something
similar but it can change the state or view of a data structure to new readers 
by a single linked list operation and a memory barrier. RCU is an extremely
powerful algorithm because of that.

bill