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: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>

1 files changed, 22 insertions, 1 deletions

diff --git a/init/Kconfig b/init/Kconfig
index be8b7f55312d..a05f843e7e52 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -326,6 +326,9 @@ source "kernel/time/Kconfig"
 
 menu "CPU/Task time and stats accounting"
 
+config VIRT_CPU_ACCOUNTING
+        bool
+
 choice
         prompt "Cputime accounting"
         default TICK_CPU_ACCOUNTING if !PPC64
@@ -342,9 +345,10 @@ config TICK_CPU_ACCOUNTING
 
           If unsure, say Y.
 
-config VIRT_CPU_ACCOUNTING
+config VIRT_CPU_ACCOUNTING_NATIVE
         bool "Deterministic task and CPU time accounting"
         depends on HAVE_VIRT_CPU_ACCOUNTING
+        select VIRT_CPU_ACCOUNTING
         help
           Select this option to enable more accurate task and CPU time
           accounting.  This is done by reading a CPU counter on each
@@ -354,6 +358,23 @@ config VIRT_CPU_ACCOUNTING
           this also enables accounting of stolen time on logically-partitioned
           systems.
 
+config VIRT_CPU_ACCOUNTING_GEN
+        bool "Full dynticks CPU time accounting"
+        depends on HAVE_CONTEXT_TRACKING && 64BIT
+        select VIRT_CPU_ACCOUNTING
+        select CONTEXT_TRACKING
+        help
+          Select this option to enable task and CPU time accounting on full
+          dynticks systems. This accounting is implemented by watching every
+          kernel-user boundaries using the context tracking subsystem.
+          The accounting is thus performed at the expense of some significant
+          overhead.
+
+          For now this is only useful if you are working on the full
+          dynticks subsystem development.
+
+          If unsure, say N.
+
 config IRQ_TIME_ACCOUNTING
         bool "Fine granularity task level IRQ time accounting"
         depends on HAVE_IRQ_TIME_ACCOUNTING