Re: [PATCH tip/core/rcu 0/6] rcu: fix synchronize_rcu_expedited(), update docs, improve perf

["Paul E. McKenney" <paulmck@linux.vnet.ibm.com>]

On Thu, Oct 15, 2009 at 01:19:44PM +0200, Ingo Molnar wrote:
> 
> * Josh Triplett <josh@joshtriplett.org> wrote:
> 
> > On Thu, Oct 15, 2009 at 11:21:55AM +0200, Ingo Molnar wrote:
> > > * Paul E. McKenney <paulmck@linux.vnet.ibm.com> wrote:
> > > 
> > > > This patchset contains a bug fix, a performance improvement, and 
> > > > documentation updates:
> > > > 
> > > > o	Update Documentation/RCU/trace.txt to reflect recent changes
> > > > 	(including the removal of rcupreempt.c).
> > > 
> > > i've applied this to the .33 queue.
> > 
> > I realize this only represents a documentation change, but it updates 
> > the documentation to match the code in 2.6.32, which seems worth 
> > doing.
> > 
> > > > o	Add the new rnp->blocked_tasks field to the rcuhier trace file
> > > > 	in debugfs.
> > > > 
> > > > o	Update the Documentation/RCU/trace.txt documentation to include
> > > > 	the rnp->blocked_tasks tracing.
> > > 
> > > i've applied these to the .33 queue as well. (both tracing and 
> > > documentation is not urgent material.) I also did minor edits to the 
> > > changelogs.
> > 
> > Those who debug RCU-related issues would disagree that having adequate 
> > tracing information proves non-urgent. :) The tracing information this 
> > adds proves essential for debugging issues with the new hierarchical 
> > RCU.  (And the documentation patch just documents the added tracing 
> > information, so both should go together as a unit; actually, perhaps 
> > they should get merged.)
> 
> No, we generally dont do such changes so late in -rc's (these would hit 
> upstream in -rc6 - which is too late).
> 
> People doing development will use the latest RCU tree so the practical 
> impact is small. Furthermore, we had a higher than usual rate of 
> post-rc1 RCU changes in this cycle already, it needs to cool down a bit.

Works for me!  I can supply appropriate diffs off of one of the -rc
releases if people need this in order to experiment with recent RCU
patches.  (But I get to choose the -rc!)

							Thanx, Paul