sched: Add IRQ_TIME_ACCOUNTING, finer accounting of irq time
authorVenkatesh Pallipadi <venki@google.com>
Tue, 5 Oct 2010 00:03:19 +0000 (17:03 -0700)
committerIngo Molnar <mingo@elte.hu>
Mon, 18 Oct 2010 18:52:24 +0000 (20:52 +0200)
commitb52bfee445d315549d41eacf2fa7c156e7d153d5
tree740f3aa24e2afad42772a662ceb460c555003c0f
parent6cdd5199daf0cb7b0fcc8dca941af08492612887
sched: Add IRQ_TIME_ACCOUNTING, finer accounting of irq time

s390/powerpc/ia64 have support for CONFIG_VIRT_CPU_ACCOUNTING which does
the fine granularity accounting of user, system, hardirq, softirq times.
Adding that option on archs like x86 will be challenging however, given the
state of TSC reliability on various platforms and also the overhead it will
add in syscall entry exit.

Instead, add a lighter variant that only does finer accounting of
hardirq and softirq times, providing precise irq times (instead of timer tick
based samples). This accounting is added with a new config option
CONFIG_IRQ_TIME_ACCOUNTING so that there won't be any overhead for users not
interested in paying the perf penalty.

This accounting is based on sched_clock, with the code being generic.
So, other archs may find it useful as well.

This patch just adds the core logic and does not enable this logic yet.

Signed-off-by: Venkatesh Pallipadi <venki@google.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1286237003-12406-5-git-send-email-venki@google.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
include/linux/hardirq.h
include/linux/sched.h
kernel/sched.c