• Ingo Molnar's avatar
    Merge tag 'full-dynticks-cputime-for-mingo' of... · b2c77a57
    Ingo Molnar authored
    Merge tag 'full-dynticks-cputime-for-mingo' of git://git.kernel.org/pub/scm/linux/kernel/git/frederic/linux-dynticks into sched/core
    
    Pull full-dynticks (user-space execution is undisturbed and
    receives no timer IRQs) preparation changes that convert the
    cputime accounting code to be full-dynticks ready,
    from Frederic Weisbecker:
    
     "This implements the cputime accounting on full dynticks CPUs.
    
      Typical cputime stats infrastructure relies on the timer tick and
      its periodic polling on the CPU to account the amount of time
      spent by the CPUs and the tasks per high level domains such as
      userspace, kernelspace, guest, ...
    
      Now we are preparing to implement full dynticks capability on
      Linux for Real Time and HPC users who want full CPU isolation.
      This feature requires a cputime accounting that doesn't depend
      on the timer tick.
    
      To implement it, this new cputime infrastructure plugs into
      kernel/user/guest boundaries to take snapshots of cputime and
      flush these to the stats when needed. This performs pretty
      much like CONFIG_VIRT_CPU_ACCOUNTING except that context location
      and cputime snaphots are synchronized between write and read
      side such that the latter can safely retrieve the pending tickless
      cputime of a task and add it to its latest cputime snapshot to
      return the correct result to the user."
    Signed-off-by: default avatarFrederic Weisbecker <fweisbec@gmail.com>
    Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
    b2c77a57
core.c 196 KB