27 Apr, 2013

1 commit

• 8c23b80ec   cputime_nsecs: use math64.h for nsec resolution conversion helpers ... Browse Code »

  For the nsec resolution conversions to be useable on non 64-bit
  architectures, the helpers in need to be used so the
  right arch-specific 64-bit math helpers can be used (e.g. do_div())

  Signed-off-by: Kevin Hilman
  Cc: Christoph Lameter
  Cc: Hakan Akkan
  Cc: Ingo Molnar
  Cc: Kevin Hilman
  Cc: Li Zhong
  Cc: Paul E. McKenney
  Cc: Paul Gortmaker
  Cc: Peter Zijlstra
  Cc: Steven Rostedt
  Cc: Thomas Gleixner
  Signed-off-by: Frederic Weisbecker

  Kevin Hilman

  2013-04-27 00:58:12 +0800  

24 Feb, 2013

1 commit

• c78a4bcd1   cputime: Constify timeval_to_cputime(timeval) argument ... Browse Code »

  Saw the following compiler warning on the linux-next tree:

  kernel/itimer.c: In function 'set_cpu_itimer':
  kernel/itimer.c:152:2: warning: passing argument 1 of 'timeval_to_cputime' discards 'const' qualifier from pointer target type [enabled by default]
  ...

  timeval_to_cputime() is always passed a constant timeval in
  argument, we need to teach the nsecs based cputime
  implementation about that.

  Signed-off-by: Li Zhong
  Signed-off-by: Frederic Weisbecker
  Cc: Steven Rostedt
  Cc: Kevin Hilman
  Link: http://lkml.kernel.org/r/1361636925-22288-2-git-send-email-fweisbec@gmail.com
  Signed-off-by: Ingo Molnar
  Cc: Steven Rostedt
  Cc: Kevin Hilman

  Li Zhong

  2013-02-24 19:57:15 +0800  

28 Jan, 2013

2 commits

• abf917cd9   cputime: Generic on-demand virtual cputime accounting ... Browse Code »

  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: Frederic Weisbecker
  Cc: Andrew Morton
  Cc: Ingo Molnar
  Cc: Li Zhong
  Cc: Namhyung Kim
  Cc: Paul E. McKenney
  Cc: Paul Gortmaker
  Cc: Peter Zijlstra
  Cc: Steven Rostedt
  Cc: Thomas Gleixner

  Frederic Weisbecker

  2013-01-28 02:23:27 +0800  
• 39613766e   cputime: Librarize per nsecs resolution cputime definitions ... Browse Code »

  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: Frederic Weisbecker
  Cc: Andrew Morton
  Cc: Ingo Molnar
  Cc: Li Zhong
  Cc: Namhyung Kim
  Cc: Paul E. McKenney
  Cc: Paul Gortmaker
  Cc: Peter Zijlstra
  Cc: Steven Rostedt
  Cc: Thomas Gleixner
  Cc: Tony Luck
  Cc: Fenghua Yu

  Frederic Weisbecker

  2013-01-28 02:23:16 +0800