lkml.org 
[lkml]   [2011]   [Nov]   [3]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH RFC tip/core/rcu 0/28] Preview of RCU changes for 3.3
On Wed, Nov 02, 2011 at 09:55:35PM -0700, Josh Triplett wrote:
> On Wed, Nov 02, 2011 at 01:30:17PM -0700, Paul E. McKenney wrote:
> > This patchset permits idle tasks to use RCU read-side critical sections,
> > although they are still prohibited between tick_nohz_idle_exit_norcu()
> > and tick_nohz_idle_exit_norcu(); makes synchronize_sched_expedited()
> > better able to share work among concurrent callers, allows ftrace_dump()
> > to be invoked from modules, dumps tracing upon detection of an rcutorture
> > failure, detects illegal use of RCU read-side critical sections from
> > extended quiescent states, legitimizes the pre-existin use of RCU in the
> > idle notifiers, fixes a memory-barrier botch, introduces an SRCU-like bulk
> > reference count, improve dynticks entry/exit tracing, further improves
> > RCU's ability to allow a given CPU to enter dyntick-idle mode quickly,
> > fixes idle-task checks, updates documentation, and additional fixes
> > from a still-ongoing top-to-bottom inspection of RCU. The patches are
> > as follows:
>
> I've reviewed all of these patches. For all of them except those
> indicated below:
> Reviewed-by: Josh Triplett <josh@joshtriplett.org>

Thank you for your careful review and thoughtful comments!

I have pushed the changes to -rcu at:

git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git rcu/dev

Could you please check to make sure that I got your Reviewed-by
on the right commits?

Thanx, Paul

> > 1. Strengthen memory barriers used in PowerPC value-returning
> > atomics and locking primitives. It is likely that this
> > commit will be superseded by something from the powerpc
> > maintainers. The need for this strengthening was validated
> > by tooling from Peter Sewell's group at the University of
> > Cambridge.
>
> As before, I don't have the background on powerpc to provide review on
> this one. However, I trust Peter Sewell's group to have gotten the
> details right. :)
>
> > 5. Document the troubleshooting of lockdep lock-class leaks.
>
> I replied with a few comments and a typo fix.
>
> > 11. Remove a useless self-awaken when setting up expedited grace
> > periods, courtesy of Thomas Gleixner and the -rt effort.
>
> Replied with a fix: commit needs splitting.
>
> > 12-17. Make lockdep-RCU warn when RCU read-side primitives are
> > invoked from an idle RCU extended quiescent state, mostly
> > courtesy of Frederic Weisbecker.
>
> Replied to 17 with a minor nit, but Reviewed-by still applies to all
> five with or without that nit fixed.
>
> > 18-23. Separate out the scheduler-clock tick's idea of dyntick
> > idle from RCU's notion of an idle extended quiescent state, mostly
> > courtesy of Frederic Weisbecker. These commits are needed for
> > Frederic's work to suppress the scheduler-clock tick when there
> > is but one runnable task on a given CPU.
>
> Very much looking forward to that work. Any pointer to more information
> on tickless-when-one-task?
>
> Replied to patch 19 with some naming comments; the rest seem fine.
>
> > 24. Introduce a bulk reference count, which is related to SRCU,
> > but which allows a reference to be acquired in an irq handler
> > and released by the task that was interrupted.
>
> Replied with comments.
>
> > 27. Allow CPUs with pending RCU callbacks to enter dyntick-idle
> > mode. Beware this commit, as it compiled and passed rcutorture
> > on the first try, which historically has indicated the presence
> > of subtle and highly destructive bugs.
>
> Heh. I reviewed this one particularly carefully, then, but I didn't
> find any logic errors. I did reply with a couple of comments, though.
>
> > 28. Fix RCU's determination of whether or not it is running in the
> > context of an idle task.
>
> Replied with concerns.
>
> - Josh Triplett
>



\
 
 \ /
  Last update: 2011-11-03 22:49    [W:0.167 / U:23.748 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site