Subj : Re: full-blown experiential smr-based reference counted pointer impl...
To   : comp.programming.threads
From : Chris Thomasson
Date : Fri Apr 01 2005 10:16 pm

>>> Yes.  Though with classical RCU the quiesent states aren't so near the
>>> critical
>>> regions and the membars are around the quiesent state itself, so they're
>>> not
>>> near the critical regions either

Humm... I guess you might be able to emulate this beneficial behavior with 
user-space RCU. For instance... If user application logic happens to consume 
a batch of events from a server workqueue, executes the batch, then goes 
back to the queue to "wait" for more batches of objects to be pushed. The 
"wait" in this case could be considered a "natural user-application" 
quiescent point. The user would process multiple events ( the batch ) before 
the quiescent state shift happens, thus the depth of the batch affects the 
distance between the per-thread quiescent state transition points... Any 
thoughts?




> With classical RCU, the quiescent states are voluntary context switches, 
> so
> the RCU read lock and unlock macros are no-ops.  That's about as less
> overhead as you can get.

Yeah. I was considering collection pop function that blocks when empty to be 
a "voluntary" user-space context switch of sorts...




> "classical RCU".  It's been around for about 20 years now.  :)

;)

.