Messages in this thread | | | From | Frederic Weisbecker <> | Subject | [RFC][PATCH 00/32] Nohz cpusets v2 (adaptive tickless kernel) | Date | Wed, 21 Mar 2012 14:58:05 +0100 |
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Hi all,
A summary of what this is about can be found here: https://lkml.org/lkml/2011/8/15/245
There are still a lot of things to handle. Especially about what is done by scheduler_tick() but we also need to:
- completely handle cputime accounting (need to find every "reader" of cputime and flush cputimes for all of them). -handle perf - handle irqtime finegrained accounting - handle ilb load balancing - etc...
Nonetheless this is time to post a new iteration of the patchset because the design has changed a bit, some bugs have been fixed, more simplification, more unification with dynticks-idle code, namespace fixes, various improvements here and there...
The git branch can be fetched from:
git://github.com/fweisbec/linux-dynticks.git nohz/cpuset-v2
Changelog since v1:
- Rebase against 3.3-rc7 + tip:timers/core branch targeted for 3.4-rc1
- Refine some changelogs
- 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.
Frederic Weisbecker (32): nohz: Separate idle sleeping time accounting from nohz logic nohz: Make nohz API agnostic against idle ticks cputime accounting nohz: Rename ts->idle_tick to ts->last_tick nohz: Move nohz load balancer selection into idle logic nohz: Move ts->idle_calls incrementation into strict idle logic nohz: Move next idle expiry time record into idle logic area cpuset: Set up interface for nohz flag nohz: Try not to give the timekeeping duty to an adaptive tickless 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 | 12 +- 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 | 20 +- arch/x86/mm/fault.c | 13 +- fs/proc/array.c | 2 + include/linux/cpuset.h | 29 ++ 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 | 75 ++++-- init/Kconfig | 8 + kernel/cpuset.c | 107 +++++++ kernel/exit.c | 8 + kernel/posix-cpu-timers.c | 12 + kernel/printk.c | 15 +- kernel/rcutree.c | 150 ++++++++-- kernel/sched/core.c | 83 ++++++- kernel/sched/sched.h | 23 ++ kernel/softirq.c | 6 +- kernel/sys.c | 6 + kernel/time/tick-sched.c | 540 +++++++++++++++++++++++++++++------- kernel/time/timer_list.c | 7 +- kernel/timer.c | 2 +- 34 files changed, 1042 insertions(+), 177 deletions(-)
-- 1.7.5.4
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