linux/kernel/time
Martin Schwidefsky 79741dd357 [PATCH] idle cputime accounting
The cpu time spent by the idle process actually doing something is
currently accounted as idle time. This is plain wrong, the architectures
that support VIRT_CPU_ACCOUNTING=y can do better: distinguish between the
time spent doing nothing and the time spent by idle doing work. The first
is accounted with account_idle_time and the second with account_system_time.
The architectures that use the account_xxx_time interface directly and not
the account_xxx_ticks interface now need to do the check for the idle
process in their arch code. In particular to improve the system vs true
idle time accounting the arch code needs to measure the true idle time
instead of just testing for the idle process.
To improve the tick based accounting as well we would need an architecture
primitive that can tell us if the pt_regs of the interrupted context
points to the magic instruction that halts the cpu.

In addition idle time is no more added to the stime of the idle process.
This field now contains the system time of the idle process as it should
be. On systems without VIRT_CPU_ACCOUNTING this will always be zero as
every tick that occurs while idle is running will be accounted as idle
time.

This patch contains the necessary common code changes to be able to
distinguish idle system time and true idle time. The architectures with
support for VIRT_CPU_ACCOUNTING need some changes to exploit this.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2008-12-31 15:11:46 +01:00
..
clockevents.c clockevents: make device shutdown robust 2008-09-16 13:47:02 -07:00
clocksource.c clocksource: keep track of original clocksource frequency 2008-08-21 09:50:23 +02:00
jiffies.c clocksource: keep track of original clocksource frequency 2008-08-21 09:50:23 +02:00
Kconfig Kconfig: eliminate "def_bool n" constructs 2008-10-16 11:21:31 -07:00
Makefile clockevents: Allow build w/o run-tine usage for migration purposes 2007-10-12 23:04:05 +02:00
ntp.c hrtimer: removing all ur callback modes 2008-11-25 15:45:46 +01:00
tick-broadcast.c NOHZ: restart tick device from irq_enter() 2008-10-17 18:13:38 +02:00
tick-common.c clockevents: prevent mode mismatch on cpu online 2008-09-23 11:38:53 +02:00
tick-internal.h NOHZ: restart tick device from irq_enter() 2008-10-17 18:13:38 +02:00
tick-oneshot.c clockevents: remove WARN_ON which was used to gather information 2008-09-09 22:20:01 +02:00
tick-sched.c [PATCH] idle cputime accounting 2008-12-31 15:11:46 +01:00
timekeeping.c time: catch xtime_nsec underflows and fix them 2008-12-04 08:43:02 +01:00
timer_list.c Merge branch 'timers/range-hrtimers' into v28-range-hrtimers-for-linus-v2 2008-10-22 09:48:06 +02:00
timer_stats.c kernel: use non-racy method for proc entries creation 2008-04-29 08:06:22 -07:00