lkml.org 
[lkml]   [2018]   [Nov]   [14]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    From
    Subject[PATCH 00/25] sched/nohz: Make kcpustat vtime aware (Fix kcpustat on nohz_full)
    Date
    Kcpustat (the stats you see for each CPU on /proc/stat) is partly
    maintained by the tick, updated by TICK_NSEC every jiffy, the same way
    we account the cputime for tasks.

    Now in the case of nohz_full, kcpustat doesn't get accounted anymore while
    the tick is stopped. Vtime maintains the task cputime but not kcpustat.

    This issue was hidden as long as we had the 1Hz remaining tick, then
    Yauheni Kaliuta made me remember that problem.

    I scratched my head a lot on this, due to all the possible races.
    The solution here is to fetch the task running on a CPU with RCU, read
    its vtime delta (like we do for cputime) and add it to the relevant
    kcpustat field. There have been several subtleties on the way (concurrent
    task nice changes, earliest RCU delayed put_task_struct(), ordering with
    vtime) and I couldn't resist a few cleanups so the patchset isn't too
    small, sorry about that...

    git://git.kernel.org/pub/scm/linux/kernel/git/frederic/linux-dynticks.git
    nohz/kcpustat

    HEAD: c7c45c06334346f62dbbf7bb12e2a8ab954532e5

    Thanks,
    Frederic
    ---

    Frederic Weisbecker (25):
    sched/vtime: Fix guest/system mis-accounting on task switch
    sched/vtime: Protect idle accounting under vtime seqcount
    vtime: Rename vtime_account_system() to vtime_account_kernel()
    vtime: Spare a seqcount lock/unlock cycle on context switch
    sched/vtime: Record CPU under seqcount for kcpustat needs
    sched/cputime: Add vtime idle task state
    sched/cputime: Add vtime guest task state
    vtime: Exit vtime before exit_notify()
    kcpustat: Track running task following vtime sequences
    context_tracking: Remove context_tracking_active()
    context_tracking: s/context_tracking_is_enabled/context_tracking_enabled()
    context_tracking: Rename context_tracking_is_cpu_enabled() to context_tracking_enabled_this_cpu()
    context_tracking: Introduce context_tracking_enabled_cpu()
    sched/vtime: Rename vtime_accounting_cpu_enabled() to vtime_accounting_enabled_this_cpu()
    sched/vtime: Introduce vtime_accounting_enabled_cpu()
    sched/cputime: Allow to pass cputime index on user/guest accounting
    sched/cputime: Standardize the kcpustat index based accounting functions
    vtime: Track nice-ness on top of context switch
    sched/vite: Handle nice updates under vtime
    sched/kcpustat: Introduce vtime-aware kcpustat accessor
    procfs: Use vtime aware kcpustat accessor
    cpufreq: Use vtime aware kcpustat accessor
    leds: Use vtime aware kcpustat accessors
    rackmeter: Use vtime aware kcpustat accessors
    sched/vtime: Clarify vtime_task_switch() argument layout


    arch/ia64/include/asm/cputime.h | 3 +-
    arch/ia64/kernel/time.c | 15 +-
    arch/powerpc/include/asm/cputime.h | 8 +-
    arch/powerpc/kernel/time.c | 12 +-
    arch/s390/kernel/vtime.c | 19 +-
    arch/x86/entry/calling.h | 2 +-
    drivers/cpufreq/cpufreq.c | 18 +-
    drivers/cpufreq/cpufreq_governor.c | 27 ++-
    drivers/leds/trigger/ledtrig-activity.c | 9 +-
    drivers/macintosh/rack-meter.c | 14 +-
    fs/proc/stat.c | 21 +-
    include/linux/context_tracking.h | 30 +--
    include/linux/context_tracking_state.h | 19 +-
    include/linux/kernel_stat.h | 28 ++-
    include/linux/sched.h | 12 +-
    include/linux/tick.h | 2 +-
    include/linux/vtime.h | 72 ++++---
    kernel/context_tracking.c | 6 +-
    kernel/exit.c | 1 +
    kernel/sched/core.c | 6 +-
    kernel/sched/cputime.c | 372 +++++++++++++++++++++++++-------
    kernel/sched/sched.h | 39 ++++
    kernel/time/tick-sched.c | 2 +-
    23 files changed, 548 insertions(+), 189 deletions(-)

    \
     
     \ /
      Last update: 2018-11-14 03:47    [W:4.242 / U:0.176 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site