On Tue, Oct 12, 2021 at 05:32:15PM -0700, Paul E. McKenney wrote: > On Mon, Oct 11, 2021 at 04:51:29PM +0200, Frederic Weisbecker wrote: > > Hi, > > > > No code change in this v2, only changelogs: > > > > * Add tags from Valentin and Sebastian > > > > * Remove last reference to SEGCBLIST_SOFTIRQ_ONLY (thanks Valentin) > > > > * Rewrite changelog for "rcu/nocb: Check a stable offloaded state to manipulate qlen_last_fqs_check" > > after off-list debates with Paul. > > > > * Remove the scenario with softirq interrupting rcuc on > > "rcu/nocb: Limit number of softirq callbacks only on softirq" as it's > > probably not possible (thanks Valentin). > > > > * Remove the scenario with task spent scheduling out accounted on tlimit > > as it's not possible (thanks Valentin) > > (see "rcu: Apply callbacks processing time limit only on softirq") > > > > * Fixed changelog of > > "rcu/nocb: Don't invoke local rcu core on callback overload from nocb kthread" > > (thanks Sebastian). > > > > git://git.kernel.org/pub/scm/linux/kernel/git/frederic/linux-dynticks.git > > rcu/rt-v2 > > > > HEAD: 2c9349986d5f70a555195139665841cd98e9aba4 > > > > Thanks, > > Frederic > > Nice! > > I queued these for further review and testing. I reworked the commit log > of 6/11 to give my idea of the reason, though I freely admit that this > reason is not as compelling as it no doubt seemed when I wrote that code. But in initial tests TREE04.5, TREE04.6, and TREE04.9 all hit the WARN_ON(1) in rcu_torture_barrier(), which indicates rcu_barrier() breakage. My best (but not so good) guess is a five-hour MTBF on a dual-socket system. I started an automated "git bisect" with each step running 100 hours of TREE04, but I would be surprised if anything useful comes of it. Pleased, mind you, but surprised. Thanx, Paul > > --- > > > > Frederic Weisbecker (10): > > rcu/nocb: Make local rcu_nocb_lock_irqsave() safe against concurrent deoffloading > > rcu/nocb: Prepare state machine for a new step > > rcu/nocb: Invoke rcu_core() at the start of deoffloading > > rcu/nocb: Make rcu_core() callbacks acceleration (de-)offloading safe > > rcu/nocb: Check a stable offloaded state to manipulate qlen_last_fqs_check > > rcu/nocb: Use appropriate rcu_nocb_lock_irqsave() > > rcu/nocb: Limit number of softirq callbacks only on softirq > > rcu: Fix callbacks processing time limit retaining cond_resched() > > rcu: Apply callbacks processing time limit only on softirq > > rcu/nocb: Don't invoke local rcu core on callback overload from nocb kthread > > > > Thomas Gleixner (1): > > rcu/nocb: Make rcu_core() callbacks acceleration preempt-safe > > > > > > include/linux/rcu_segcblist.h | 51 ++++++++++++++++++------- > > kernel/rcu/rcu_segcblist.c | 10 ++--- > > kernel/rcu/rcu_segcblist.h | 12 +++--- > > kernel/rcu/tree.c | 87 +++++++++++++++++++++++++++++-------------- > > kernel/rcu/tree.h | 16 +++++--- > > kernel/rcu/tree_nocb.h | 29 ++++++++++++--- > > 6 files changed, 141 insertions(+), 64 deletions(-)
