1. 27 Jan, 2013 2 commits
    • Frederic Weisbecker's avatar
      cputime: Generic on-demand virtual cputime accounting · abf917cd
      Frederic Weisbecker authored
      
      
      If we want to stop the tick further idle, we need to be
      able to account the cputime without using the tick.
      
      Virtual based cputime accounting solves that problem by
      hooking into kernel/user boundaries.
      
      However implementing CONFIG_VIRT_CPU_ACCOUNTING require
      low level hooks and involves more overhead. But we already
      have a generic context tracking subsystem that is required
      for RCU needs by archs which plan to shut down the tick
      outside idle.
      
      This patch implements a generic virtual based cputime
      accounting that relies on these generic kernel/user hooks.
      
      There are some upsides of doing this:
      
      - This requires no arch code to implement CONFIG_VIRT_CPU_ACCOUNTING
      if context tracking is already built (already necessary for RCU in full
      tickless mode).
      
      - We can rely on the generic context tracking subsystem to dynamically
      (de)activate the hooks, so that we can switch anytime between virtual
      and tick based accounting. This way we don't have the overhead
      of the virtual accounting when the tick is running periodically.
      
      And one downside:
      
      - There is probably more overhead than a native virtual based cputime
      accounting. But this relies on hooks that are already set anyway.
      Signed-off-by: default avatarFrederic Weisbecker <fweisbec@gmail.com>
      Cc: Andrew Morton <akpm@linux-foundation.org>
      Cc: Ingo Molnar <mingo@kernel.org>
      Cc: Li Zhong <zhong@linux.vnet.ibm.com>
      Cc: Namhyung Kim <namhyung.kim@lge.com>
      Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
      Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Steven Rostedt <rostedt@goodmis.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      abf917cd
    • Frederic Weisbecker's avatar
      cputime: Librarize per nsecs resolution cputime definitions · 39613766
      Frederic Weisbecker authored
      
      
      The full dynticks cputime accounting that we'll soon introduce
      will rely on sched_clock(). And its clock can have a per
      nanosecond granularity.
      
      To prepare for this, we need to have a cputime_t implementation
      that has this precision.
      
      ia64 virtual cputime accounting already uses that granularity
      so all we need is to librarize its implementation in the asm
      generic headers.
      
      Also librarize the default per jiffy granularity cputime_t
      as well so that we can easily pick either implementation
      depending on the cputime accounting config we choose.
      Signed-off-by: default avatarFrederic Weisbecker <fweisbec@gmail.com>
      Cc: Andrew Morton <akpm@linux-foundation.org>
      Cc: Ingo Molnar <mingo@kernel.org>
      Cc: Li Zhong <zhong@linux.vnet.ibm.com>
      Cc: Namhyung Kim <namhyung.kim@lge.com>
      Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
      Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Steven Rostedt <rostedt@goodmis.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: Tony Luck <tony.luck@intel.com>
      Cc: Fenghua Yu <fenghua.yu@intel.com>
      39613766
  2. 16 Jan, 2013 2 commits
  3. 15 Jan, 2013 1 commit
  4. 14 Jan, 2013 4 commits
  5. 13 Jan, 2013 2 commits
  6. 12 Jan, 2013 3 commits
  7. 11 Jan, 2013 5 commits
  8. 10 Jan, 2013 4 commits
  9. 08 Jan, 2013 13 commits
  10. 07 Jan, 2013 4 commits