From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757405Ab1LNQaU (ORCPT ); Wed, 14 Dec 2011 11:30:20 -0500 Received: from mail-qw0-f46.google.com ([209.85.216.46]:62314 "EHLO mail-qw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754969Ab1LNQaQ (ORCPT ); Wed, 14 Dec 2011 11:30:16 -0500 Date: Wed, 14 Dec 2011 17:30:11 +0100 From: Frederic Weisbecker To: Ingo Molnar Cc: "Paul E. McKenney" , Suresh Siddha , Peter Zijlstra , tglx@linutronix.de, josh@joshtriplett.org, keescook@chromium.org, linux-kernel@vger.kernel.org Subject: Re: [GIT PULL rcu/next] RCU commits for 3.3 Message-ID: <20111214163007.GD10791@somewhere.redhat.com> References: <20111213230243.GA15127@linux.vnet.ibm.com> <20111214154736.GA2419@elte.hu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20111214154736.GA2419@elte.hu> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Dec 14, 2011 at 04:47:36PM +0100, Ingo Molnar wrote: > > * Paul E. McKenney wrote: > > > Hello, Ingo, > > > > The major features of this series are RCU infrastructure in > > support of Frederic Weisbecker's tickless userspace work and a > > reworked RCU_FAST_NO_HZ that improves energy efficiency on > > large lightly loaded SMP systems by allowing the > > scheduler-clock tick to be turned off more quickly upon entry > > to idle, even when RCU callbacks are queued on the newly idle > > CPU. In addition, RCU_FAST_NO_HZ may now be used on systems > > running TREE_PREEMPT_RCU, where earlier it was restricted to > > TREE_RCU. > > > > In addition, this series provides additional event tracing, > > rcutorture changes that improve automated KVM-based testing of > > RCU, introduces an srcu_read_lock_raw() needed by uprobes, and > > ports a couple of patches from -rt to mainline. Finally, this > > series updates documentation, improves diagnostics, and fixes > > a number of bugs, including a nasty use of RCU from the idle > > task spotted and fixed by Frederic Weisbecker. > > > > These commits have been posted to LKML and updated based on > > feedback: > > > > https://lkml.org/lkml/2011/11/2/363 > > https://lkml.org/lkml/2011/11/15/302 > > https://lkml.org/lkml/2011/11/28/588 > > https://lkml.org/lkml/2011/12/3/77 > > https://lkml.org/lkml/2011/12/12/625 > > > > They have also been exposed to -next testing. > > > > These changes are based off of 3.2-rc5 and are available at > > the git repository at: > > > > git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git rcu/next > > > > Could you please pull them into -tip for additional testing? > > > > Thanx, Paul > > > > ------------------> > > Frederic Weisbecker (11): > > rcu: Detect illegal rcu dereference in extended quiescent state > > rcu: Inform the user about extended quiescent state on PROVE_RCU warning > > rcu: Warn when rcu_read_lock() is used in extended quiescent state > > nohz: Separate out irq exit and idle loop dyntick logic > > nohz: Allow rcu extended quiescent state handling seperately from tick stop > > x86: Enter rcu extended qs after idle notifier call > > x86: Call idle notifier after irq_enter() > > rcu: Fix early call to rcu_idle_enter() > > nohz: Remove tick_nohz_idle_enter_norcu() / tick_nohz_idle_exit_norcu() > > rcu: Don't check irq nesting from rcu idle entry/exit > > rcu: Irq nesting is always 0 on rcu_enter_idle_common > > > > Josh Triplett (1): > > driver-core/cpu: Expose hotpluggability to the rest of the kernel > > > > Kees Cook (1): > > docs: Additional LWN links to RCU API > > > > Paul E. McKenney (49): > > rcu: ->signaled better named ->fqs_state > > rcu: Avoid RCU-preempt expedited grace-period botch > > rcu: Make synchronize_sched_expedited() better at work sharing > > lockdep: Update documentation for lock-class leak detection > > rcu: Track idleness independent of idle tasks > > trace: Allow ftrace_dump() to be called from modules > > rcu: Add failure tracing to rcutorture > > rcu: Document failing tick as cause of RCU CPU stall warning > > rcu: Disable preemption in rcu_is_cpu_idle() > > rcu: Remove one layer of abstraction from PROVE_RCU checking > > rcu: Warn when srcu_read_lock() is used in an extended quiescent state > > rcu: Make srcu_read_lock_held() call common lockdep-enabled function > > powerpc: Tell RCU about idle after hcall tracing > > rcu: Introduce raw SRCU read-side primitives > > rcu: Add documentation for raw SRCU read-side primitives > > rcu: Deconfuse dynticks entry-exit tracing > > rcu: Add more information to the wrong-idle-task complaint > > rcu: Allow dyntick-idle mode for CPUs with callbacks > > rcu: Fix idle-task checks > > rcu: Permit RCU_FAST_NO_HZ to be used by TREE_PREEMPT_RCU > > rcu: Add rcutorture system-shutdown capability > > rcu: Control rcutorture startup from kernel boot parameters > > sched: Add is_idle_task() to handle invalidated uses of idle_cpu() > > rcu: Make RCU use the new is_idle_task() API > > sparc: Make SPARC use the new is_idle_task() API > > kdb: Make KDB use the new is_idle_task() API > > events: Make events use the new is_idle_task() API > > tile: Make tile use the new is_idle_task() API > > rcu: Add rcutorture CPU-hotplug capability > > doc: Add load/store guarantees to Documentation/atomic-ops.txt > > rcu: Update trace_rcu_dyntick() header comment > > rcu: Add tracing for RCU_FAST_NO_HZ > > rcu: Go dyntick-idle more quickly if CPU has serviced current grace period > > rcu: Avoid needlessly IPIing CPUs at GP end > > rcu: Eliminate RCU_FAST_NO_HZ grace-period hang > > rcu: Reduce latency of rcu_prepare_for_idle() > > rcu: Remove dynticks false positives and RCU failures > > rcu: Identify dyntick-idle CPUs on first force_quiescent_state() pass > > rcu: Document same-context read-side constraints > > rcu: Permit dyntick-idle with callbacks pending > > rcu: Keep invoking callbacks if CPU otherwise idle > > rcu: Adaptive dyntick-idle preparation > > rcu: Remove redundant rcu_cpu_stall_suppress declaration > > rcu: Make rcutorture test for hotpluggability before offlining CPUs > > rcu: Add rcutorture tests for srcu_read_lock_raw() > > rcu: Augment rcu_batch_end tracing for idle and callback state > > Revert "rcu: Permit rt_mutex_unlock() with irqs disabled" > > rcu: Apply ACCESS_ONCE() to rcu_boost() return value > > cpu: Export cpu_up() > > > > Thomas Gleixner (2): > > rcu: Omit self-awaken when setting up expedited grace period > > rcu: Remove redundant return from rcu_report_exp_rnp() > > > > Documentation/RCU/checklist.txt | 6 + > > Documentation/RCU/rcu.txt | 10 +- > > Documentation/RCU/stallwarn.txt | 16 +- > > Documentation/RCU/torture.txt | 13 ++ > > Documentation/RCU/trace.txt | 4 - > > Documentation/RCU/whatisRCU.txt | 19 ++- > > Documentation/atomic_ops.txt | 87 +++++++++ > > Documentation/lockdep-design.txt | 63 +++++++ > > arch/arm/kernel/process.c | 6 +- > > arch/avr32/kernel/process.c | 6 +- > > arch/blackfin/kernel/process.c | 6 +- > > arch/microblaze/kernel/process.c | 6 +- > > arch/mips/kernel/process.c | 6 +- > > arch/openrisc/kernel/idle.c | 6 +- > > arch/powerpc/kernel/idle.c | 15 ++- > > arch/powerpc/platforms/iseries/setup.c | 12 +- > > arch/powerpc/platforms/pseries/lpar.c | 4 + > > arch/s390/kernel/process.c | 6 +- > > arch/sh/kernel/idle.c | 6 +- > > arch/sparc/kernel/process_64.c | 6 +- > > arch/sparc/kernel/setup_32.c | 2 +- > > arch/tile/kernel/process.c | 6 +- > > arch/tile/mm/fault.c | 4 +- > > arch/um/kernel/process.c | 6 +- > > arch/unicore32/kernel/process.c | 6 +- > > arch/x86/kernel/apic/apic.c | 6 +- > > arch/x86/kernel/apic/io_apic.c | 2 +- > > arch/x86/kernel/cpu/mcheck/therm_throt.c | 2 +- > > arch/x86/kernel/cpu/mcheck/threshold.c | 2 +- > > arch/x86/kernel/irq.c | 6 +- > > arch/x86/kernel/process_32.c | 6 +- > > arch/x86/kernel/process_64.c | 10 +- > > drivers/base/cpu.c | 7 + > > include/linux/cpu.h | 1 + > > include/linux/hardirq.h | 21 --- > > include/linux/rcupdate.h | 115 ++++++++----- > > include/linux/sched.h | 8 + > > include/linux/srcu.h | 87 ++++++++-- > > include/linux/tick.h | 11 +- > > include/trace/events/rcu.h | 122 +++++++++++-- > > init/Kconfig | 10 +- > > kernel/cpu.c | 1 + > > kernel/debug/kdb/kdb_support.c | 2 +- > > kernel/events/core.c | 2 +- > > kernel/lockdep.c | 22 +++ > > kernel/rcu.h | 7 + > > kernel/rcupdate.c | 12 ++ > > kernel/rcutiny.c | 149 +++++++++++++-- > > kernel/rcutiny_plugin.h | 29 +++- > > kernel/rcutorture.c | 225 ++++++++++++++++++++++- > > kernel/rcutree.c | 290 +++++++++++++++++++++--------- > > kernel/rcutree.h | 26 ++-- > > kernel/rcutree_plugin.h | 289 ++++++++++++++++++++++++------ > > kernel/rcutree_trace.c | 12 +- > > kernel/rtmutex.c | 8 - > > kernel/softirq.c | 4 +- > > kernel/time/tick-sched.c | 97 ++++++---- > > kernel/trace/trace.c | 1 + > > 58 files changed, 1512 insertions(+), 407 deletions(-) > > Pulled into tip:core/rcu, thanks a lot Paul! > > Note that this commit from Frederic: > > 69e1e811dcc4: sched, nohz: Track nr_busy_cpus in the sched_group_power > > conflicted with this commit from Suresh in sched/core: > > 69e1e811dcc4: sched, nohz: Track nr_busy_cpus in the sched_group_power > > I resolved it by making the set_cpu_sd_state_idle() call > unconditional within the newly decoupled > tick_nohz_stop_sched_tick() function - please double check that > it's the right resolution. After a quick look, I believe this should rather be under tick_nohz_idle_enter(), (This is the equivalent of the old tick_nohz_stop_sched_tick(1)) This wants to be set only once we enter idle, not everytime we have an idle interrupt.