lkml.org 
[lkml]   [2017]   [Oct]   [27]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    Date
    From
    Subject[tip:sched/core] sched/isolation: Handle the nohz_full= parameter
    Commit-ID:  6f1982fedd59856bcc42a9b521be4c3ffd2f60a7
    Gitweb: https://git.kernel.org/tip/6f1982fedd59856bcc42a9b521be4c3ffd2f60a7
    Author: Frederic Weisbecker <frederic@kernel.org>
    AuthorDate: Fri, 27 Oct 2017 04:42:36 +0200
    Committer: Ingo Molnar <mingo@kernel.org>
    CommitDate: Fri, 27 Oct 2017 09:55:30 +0200

    sched/isolation: Handle the nohz_full= parameter

    We want to centralize the isolation management, done by the housekeeping
    subsystem. Therefore we need to handle the nohz_full= parameter from
    there.

    Since nohz_full= so far has involved unbound timers, watchdog, RCU
    and tilegx NAPI isolation, we keep that default behaviour.

    nohz_full= will be deprecated in the future. We want to control
    the isolation features from the isolcpus= parameter.

    Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
    Acked-by: Thomas Gleixner <tglx@linutronix.de>
    Cc: Chris Metcalf <cmetcalf@mellanox.com>
    Cc: Christoph Lameter <cl@linux.com>
    Cc: Linus Torvalds <torvalds@linux-foundation.org>
    Cc: Luiz Capitulino <lcapitulino@redhat.com>
    Cc: Mike Galbraith <efault@gmx.de>
    Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: Rik van Riel <riel@redhat.com>
    Cc: Wanpeng Li <kernellwp@gmail.com>
    Link: http://lkml.kernel.org/r/1509072159-31808-10-git-send-email-frederic@kernel.org
    Signed-off-by: Ingo Molnar <mingo@kernel.org>
    ---
    include/linux/sched/isolation.h | 1 +
    include/linux/tick.h | 2 ++
    init/Kconfig | 1 -
    kernel/sched/isolation.c | 42 +++++++++++++++++++++++++++++------------
    kernel/time/tick-sched.c | 13 +++----------
    5 files changed, 36 insertions(+), 23 deletions(-)

    diff --git a/include/linux/sched/isolation.h b/include/linux/sched/isolation.h
    index 9bb753e..e53cfa9 100644
    --- a/include/linux/sched/isolation.h
    +++ b/include/linux/sched/isolation.h
    @@ -10,6 +10,7 @@ enum hk_flags {
    HK_FLAG_RCU = (1 << 1),
    HK_FLAG_MISC = (1 << 2),
    HK_FLAG_SCHED = (1 << 3),
    + HK_FLAG_TICK = (1 << 4),
    };

    #ifdef CONFIG_CPU_ISOLATION
    diff --git a/include/linux/tick.h b/include/linux/tick.h
    index 68afc09..e2a163a 100644
    --- a/include/linux/tick.h
    +++ b/include/linux/tick.h
    @@ -228,6 +228,7 @@ static inline void tick_dep_clear_signal(struct signal_struct *signal,

    extern void tick_nohz_full_kick_cpu(int cpu);
    extern void __tick_nohz_task_switch(void);
    +extern void __init tick_nohz_full_setup(cpumask_var_t cpumask);
    #else
    static inline bool tick_nohz_full_enabled(void) { return false; }
    static inline bool tick_nohz_full_cpu(int cpu) { return false; }
    @@ -248,6 +249,7 @@ static inline void tick_dep_clear_signal(struct signal_struct *signal,

    static inline void tick_nohz_full_kick_cpu(int cpu) { }
    static inline void __tick_nohz_task_switch(void) { }
    +static inline void tick_nohz_full_setup(cpumask_var_t cpumask) { }
    #endif

    static inline void tick_nohz_task_switch(void)
    diff --git a/init/Kconfig b/init/Kconfig
    index 6f52e6f..f8564df 100644
    --- a/init/Kconfig
    +++ b/init/Kconfig
    @@ -474,7 +474,6 @@ endmenu # "CPU/Task time and stats accounting"

    config CPU_ISOLATION
    bool "CPU isolation"
    - depends on NO_HZ_FULL
    help
    Make sure that CPUs running critical tasks are not disturbed by
    any source of "noise" such as unbound workqueues, timers, kthreads...
    diff --git a/kernel/sched/isolation.c b/kernel/sched/isolation.c
    index 37a138a..1f61e44 100644
    --- a/kernel/sched/isolation.c
    +++ b/kernel/sched/isolation.c
    @@ -54,23 +54,41 @@ EXPORT_SYMBOL_GPL(housekeeping_test_cpu);

    void __init housekeeping_init(void)
    {
    - if (!tick_nohz_full_enabled())
    + if (!housekeeping_flags)
    return;

    - if (!alloc_cpumask_var(&housekeeping_mask, GFP_KERNEL)) {
    - WARN(1, "NO_HZ: Can't allocate not-full dynticks cpumask\n");
    - cpumask_clear(tick_nohz_full_mask);
    - tick_nohz_full_running = false;
    - return;
    + static_branch_enable(&housekeeping_overriden);
    +
    + /* We need at least one CPU to handle housekeeping work */
    + WARN_ON_ONCE(cpumask_empty(housekeeping_mask));
    +}
    +
    +#ifdef CONFIG_NO_HZ_FULL
    +static int __init housekeeping_nohz_full_setup(char *str)
    +{
    + cpumask_var_t non_housekeeping_mask;
    +
    + alloc_bootmem_cpumask_var(&non_housekeeping_mask);
    + if (cpulist_parse(str, non_housekeeping_mask) < 0) {
    + pr_warn("Housekeeping: Incorrect nohz_full cpumask\n");
    + free_bootmem_cpumask_var(non_housekeeping_mask);
    + return 0;
    }

    - cpumask_andnot(housekeeping_mask,
    - cpu_possible_mask, tick_nohz_full_mask);
    + alloc_bootmem_cpumask_var(&housekeeping_mask);
    + cpumask_andnot(housekeeping_mask, cpu_possible_mask, non_housekeeping_mask);

    - housekeeping_flags = HK_FLAG_TIMER | HK_FLAG_RCU | HK_FLAG_MISC;
    + if (cpumask_empty(housekeeping_mask))
    + cpumask_set_cpu(smp_processor_id(), housekeeping_mask);

    - static_branch_enable(&housekeeping_overriden);
    + housekeeping_flags = HK_FLAG_TICK | HK_FLAG_TIMER |
    + HK_FLAG_RCU | HK_FLAG_MISC;

    - /* We need at least one CPU to handle housekeeping work */
    - WARN_ON_ONCE(cpumask_empty(housekeeping_mask));
    + tick_nohz_full_setup(non_housekeeping_mask);
    +
    + free_bootmem_cpumask_var(non_housekeeping_mask);
    +
    + return 1;
    }
    +__setup("nohz_full=", housekeeping_nohz_full_setup);
    +#endif
    diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
    index 27d7d52..69f3dbe 100644
    --- a/kernel/time/tick-sched.c
    +++ b/kernel/time/tick-sched.c
    @@ -385,20 +385,13 @@ out:
    local_irq_restore(flags);
    }

    -/* Parse the boot-time nohz CPU list from the kernel parameters. */
    -static int __init tick_nohz_full_setup(char *str)
    +/* Get the boot-time nohz CPU list from the kernel parameters. */
    +void __init tick_nohz_full_setup(cpumask_var_t cpumask)
    {
    alloc_bootmem_cpumask_var(&tick_nohz_full_mask);
    - if (cpulist_parse(str, tick_nohz_full_mask) < 0) {
    - pr_warn("NO_HZ: Incorrect nohz_full cpumask\n");
    - free_bootmem_cpumask_var(tick_nohz_full_mask);
    - return 1;
    - }
    + cpumask_copy(tick_nohz_full_mask, cpumask);
    tick_nohz_full_running = true;
    -
    - return 1;
    }
    -__setup("nohz_full=", tick_nohz_full_setup);

    static int tick_nohz_cpu_down(unsigned int cpu)
    {
    \
     
     \ /
      Last update: 2017-10-28 20:17    [W:4.067 / U:0.072 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site