From: Tomasz Buchert on
During our work we encountered a problem of obtaining
a reliable and fine-grained measurements of CPU time/wall time
of a process/thread. The existing methods (taskstats, procfs,
POSIX CPU clocks) have either unfriendly interface (taskstats)
or give unsatisfactory precision (procfs). However, even
the most precise and clean interface, POSIX CPU clocks,
is limited only to threads in the same thread group.

The following patches introduce three changes:
* new per process/thread wall time clocks --
one can also access wall time of a process/thread
using clocks constructed from macros in posix-timers.h
* less restricted access to CPU and wall clocks --
user can access them for all their threads
* minor refactoring/renaming to reflect the changes.

Tomasz Buchert (4):
posix-timers: Refactoring of CPUCLOCK* macros
posix-cpu-timers: Introduction of wall clocks
posix-cpu-timers: Wider access to the thread clocks
posix-cpu-timers: posix-cpu-timers.c renamed to posix-task-timers.c

include/linux/posix-timers.h | 52 +-
include/linux/sched.h | 2 +-
include/linux/time.h | 2 +
kernel/Makefile | 2 +-
kernel/itimer.c | 14 +-
kernel/posix-cpu-timers.c | 1642 -------------------------------------
kernel/posix-task-timers.c | 1852 ++++++++++++++++++++++++++++++++++++++++++
kernel/posix-timers.c | 25 +-
8 files changed, 1924 insertions(+), 1667 deletions(-)
delete mode 100644 kernel/posix-cpu-timers.c
create mode 100644 kernel/posix-task-timers.c

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