Re: [ANNOUNCE] Nohz cpusets (adaptive tickless kernel)v2-pre-20120308
From: Frederic Weisbecker
Date: Wed Mar 07 2012 - 22:12:32 EST
On Thu, Mar 08, 2012 at 03:57:40AM +0100, Frederic Weisbecker wrote:
> Hi everyone,
>
> Reminder of what it's all about: https://lkml.org/lkml/2011/8/15/245
>
> The whole patchset has moved forward enough that it's now time
> to release a new iteration of it. I plan to post all the patches
> soon to LKML but before that I would like to rebase against 3.3[-rc >= 6]
> and clean up a few little things, especially revisit some changelogs.
>
> So before that to happen, I still wanted to do a release in order
> to keep everyone in touch with latest changes.
>
> Latest changes can be found at:
>
> git://github.com/fweisbec/linux-dynticks.git
> nohz/cpuset-v2-pre-20120308
>
> There is still a lot to do, but I'm glad we made some progresses with
> more idle/adaptive tickless code unification, namespace cleanups,
> RCU fixes, and various bugfixes here and there, etc...
>
> Changes since v1 (https://lkml.org/lkml/2011/8/15/245):
>
> - Rebase against latest Paul McKenney's rcu/core branch for v3.3-rc1
>
> - Adapt against latest rcu changes: introduce new APIs
> rcu_user_enter(), rcu_user_exit(), rcu_user_enter_irq()
> and rcu_user_exit_irq()
>
> - Handle RCU idle mode with do_notify_resume() path
>
> - Fix deadlock after double rq lock on schedule:
> schedule() -> rq_lock -> next is idle task ->
> tick_nohz_restart_sched_tick() -> wake up softirq ->
> rq lock
>
> - Fix lockup while issuing flush times IPI on exit path:
>
> CPU 0 CPU 1
>
> read_lock(tasklist_lock)
> write_lock_irq(tasklist_lock)
> smp_call_function(CPU 1)
> * deadlock *
>
> - Many namespace renames (cpuset_* to tick_nohz_*) and code migration
> from sched.c to tick-sched.c
>
> - Seperate code that determine if we can stop the idle tick and don't
> use it for adaptive tickless mode.
>
> - Fix adaptive tickless mode set on idle incidentally. TIF_NOHZ was
> then missing on the following task that ran tickless, issuing some
> illegal uses of RCU
>
> - Restart the tick anytime more than one task is on the runqueue. We were previously
> only covering wake ups, now we also handle migration and any other source of task enqueuing
>
> - Handle use of RCU in schedule() when called right before resuming userspace
> (new schedule_user() API)
>
> - Take the decision to stop the tick from irq exit instead of the middle of the timer
> interrupt. This gives more opportunity to stop it and is one step more to unify idle
> and adaptive tickless.
>
> - Unify tickless idle and tickless user/system CPU time accounting infrastructures.
>
> - If the tick is stopped adaptively and we are going to schedule the idle
> task, don't restart the tick.
>
> - Remove task_nohz_mode per cpu var and use ts->tick_stopped instead. This
> leads to more unification between idle tickless and adaptive tickless.
>
> Have fun!
Frederic Weisbecker (34):
nohz: Drop useless call in tick_nohz_start_idle()
nohz: Drop useless ts->inidle checks on idle exit
nohz: Separate idle sleeping time accounting from nohz switching
nohz: Move idle ticks stats tracking out of nohz handlers
nohz: Rename ts->idle_tick to ts->last_tick
nohz: Move nohz load balancer selection into idle logic
nohz: Move ts->idle_calls into strict idle logic
nohz: Move next idle expiring time record into idle logic area
cpuset: Set up interface for nohz flag
nohz: Try not to give the timekeeping duty to a cpuset nohz cpu
x86: New cpuset nohz irq vector
nohz: Adaptive tick stop and restart on nohz cpuset
nohz/cpuset: Don't turn off the tick if rcu needs it
nohz/cpuset: Wake up adaptive nohz CPU when a timer gets enqueued
nohz/cpuset: Don't stop the tick if posix cpu timers are running
nohz/cpuset: Restart tick when nohz flag is cleared on cpuset
nohz/cpuset: Restart the tick if printk needs it
rcu: Restart the tick on non-responding adaptive nohz CPUs
rcu: Restart tick if we enqueue a callback in a nohz/cpuset CPU
nohz: Generalize tickless cpu time accounting
nohz/cpuset: Account user and system times in adaptive nohz mode
nohz/cpuset: New API to flush cputimes on nohz cpusets
nohz/cpuset: Flush cputime on threads in nohz cpusets when waiting leader
nohz/cpuset: Flush cputimes on procfs stat file read
nohz/cpuset: Flush cputimes for getrusage() and times() syscalls
x86: Syscall hooks for nohz cpusets
x86: Exception hooks for nohz cpusets
x86: Add adaptive tickless hooks on do_notify_resume()
nohz: Don't restart the tick before scheduling to idle
rcu: New rcu_user_enter() and rcu_user_exit() APIs
rcu: New rcu_user_enter_irq() and rcu_user_exit_irq() APIs
rcu: Switch to extended quiescent state in userspace from nohz cpuset
nohz: Exit RCU idle mode when we schedule before resuming userspace
nohz/cpuset: Disable under some configs
---
arch/Kconfig | 3 +
arch/x86/Kconfig | 1 +
arch/x86/include/asm/entry_arch.h | 3 +
arch/x86/include/asm/hw_irq.h | 7 +
arch/x86/include/asm/irq_vectors.h | 2 +
arch/x86/include/asm/smp.h | 11 +
arch/x86/include/asm/thread_info.h | 10 +-
arch/x86/kernel/entry_64.S | 14 +-
arch/x86/kernel/irqinit.c | 4 +
arch/x86/kernel/ptrace.c | 10 +
arch/x86/kernel/signal.c | 3 +
arch/x86/kernel/smp.c | 26 ++
arch/x86/kernel/traps.c | 22 +-
arch/x86/mm/fault.c | 13 +-
fs/proc/array.c | 2 +
include/linux/cpuset.h | 26 ++
include/linux/kernel_stat.h | 2 +
include/linux/posix-timers.h | 1 +
include/linux/rcupdate.h | 8 +
include/linux/sched.h | 10 +-
include/linux/tick.h | 76 ++++--
init/Kconfig | 8 +
kernel/cpuset.c | 105 +++++++
kernel/exit.c | 8 +
kernel/posix-cpu-timers.c | 12 +
kernel/printk.c | 15 +-
kernel/rcutree.c | 156 ++++++++---
kernel/sched.c | 98 +++++++-
kernel/softirq.c | 5 +-
kernel/sys.c | 6 +
kernel/time/tick-sched.c | 534 ++++++++++++++++++++++++++++--------
kernel/time/timer_list.c | 7 +-
kernel/timer.c | 2 +-
33 files changed, 1018 insertions(+), 192 deletions(-)
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