Subj : Re: Atomic Ptr Plus (formerly known as NPTL2)
To   : comp.programming.threads
From : Joseph Seigh
Date : Fri Jan 21 2005 09:48 am

The lock-free condvar and RCU for preemptive user threads is
out on the atomic-ptr-plus along with a slightly buggy
RCU testcase.  Don't set the limiting semaphore to more
than there are buffers or it will seqfault.

The testcase has read threads traversing a linked list
while writer threads are concurrently modifying the list.
The testcase lets you vary the read and write rates to see
the effect on the different techniques (at this point just
RCU and mutex).  I left rwlocks out because when I did
use them there really wasn't much difference between them
and mutexes when there is any appreciable modification.
Plus they don't seem to work on Linux yet.

The atomic ptr proxy stuff is no-op'd until I decide what
to do with it.

Everything is pre-alpha, not pre-beta like I say on the site.
I haven't started cleanup on the code yet.  When I do most
of the performance and debugging instrumentation may go
away.  Code may be missing the odd memory barrier and
the macros to identify the atomic load dependent stuff.
Plus some logic may change.  The RCU polling can be slightly
optimized a little bit more.

-- 
Joe Seigh

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