linux-toradex.git/arch/s390/include/asm/cputime.h, branch v3.2.32

procfs: do not confuse jiffies with cputime64_t

2011-12-30T00:31:57+00:00

Commit 2a95ea6c0d129b4 ("procfs: do not overflow get_{idle,iowait}_time
for nohz") did not take into account that one some architectures jiffies
and cputime use different units.

This causes get_idle_time() to return numbers in the wrong units, making
the idle time fields in /proc/stat wrong.

Instead of converting the usec value returned by
get_cpu_{idle,iowait}_time_us to units of jiffies, use the new function
usecs_to_cputime64 to convert it to the correct unit of cputime64_t.

Signed-off-by: Andreas Schwab 
Acked-by: Michal Hocko 
Cc: Arnd Bergmann 
Cc: "Artem S. Tashkinov" 
Cc: Dave Jones 
Cc: Alexey Dobriyan 
Cc: Thomas Gleixner 
Cc: "Luck, Tony" 
Cc: Benjamin Herrenschmidt 
Cc: Martin Schwidefsky 
Cc: Heiko Carstens 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[S390] nohz: optimize arch_needs_cpu()

2011-01-05T11:47:28+00:00

arch_needs_cpu() gets always executed on the current cpu. Therefore
the cpu parameter can be ignored it is possible to use __get_cpu_var()
instead of per_cpu() to access the per_cpu variable, which will
generate better code.

Signed-off-by: Heiko Carstens 
Signed-off-by: Martin Schwidefsky

taskstats: use real microsecond granularity for CPU times

2010-10-28T01:03:17+00:00

The taskstats interface uses microsecond granularity for the user and
system time values.  The conversion from cputime to the taskstats values
uses the cputime_to_msecs primitive which effectively limits the
granularity to milliseconds.  Add the cputime_to_usecs primitive for
architectures that have better, more precise CPU time values.  Remove
cputime_to_msecs primitive because there are no more users left.

Signed-off-by: Michael Holzheu 
Acked-by: Balbir Singh 
Cc: Luck Tony 
Cc: Shailabh Nagar 
Cc: Martin Schwidefsky 
Cc: Oleg Nesterov 
Cc: Benjamin Herrenschmidt 
Cc: Heiko Carstens 
Cc: Thomas Gleixner 
Cc: Shailabh Nagar 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[S390] idle time accounting vs. machine checks

2010-05-17T08:00:15+00:00

A machine check can interrupt the i/o and external interrupt handler
anytime. If the machine check occurs while the interrupt handler is
waking up from idle vtime_start_cpu can get executed a second time
and the int_clock / async_enter_timer values in the lowcore get
clobbered. This can confuse the cpu time accounting.
To fix this problem two changes are needed. First the machine check
handler has to use its own copies of int_clock and async_enter_timer,
named mcck_clock and mcck_enter_timer. Second the nested execution
of vtime_start_cpu has to be prevented. This is done in s390_idle_check
by checking the wait bit in the program status word.

Signed-off-by: Martin Schwidefsky

Merge branch 'timers-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

2009-12-09T03:27:08+00:00

* 'timers-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  timers, init: Limit the number of per cpu calibration bootup messages
  posix-cpu-timers: optimize and document timer_create callback
  clockevents: Add missing include to pacify sparse
  x86: vmiclock: Fix printk format
  x86: Fix printk format due to variable type change
  sparc: fix printk for change of variable type
  clocksource/events: Fix fallout of generic code changes
  nohz: Allow 32-bit machines to sleep for more than 2.15 seconds
  nohz: Track last do_timer() cpu
  nohz: Prevent clocksource wrapping during idle
  nohz: Type cast printk argument
  mips: Use generic mult/shift factor calculation for clocks
  clocksource: Provide a generic mult/shift factor calculation
  clockevents: Use u32 for mult and shift factors
  nohz: Introduce arch_needs_cpu
  nohz: Reuse ktime in sub-functions of tick_check_idle.
  time: Remove xtime_cache
  time: Implement logarithmic time accumulation

nohz: Introduce arch_needs_cpu

2009-11-05T06:53:53+00:00

Allow the architecture to request a normal jiffy tick when the system
goes idle and tick_nohz_stop_sched_tick is called . On s390 the hook is
used to prevent the system going fully idle if there has been an
interrupt other than a clock comparator interrupt since the last wakeup.

On s390 the HiperSockets response time for 1 connection ping-pong goes
down from 42 to 34 microseconds. The CPU cost decreases by 27%.

Signed-off-by: Martin Schwidefsky 
LKML-Reference: <20090929122533.402715150@de.ibm.com>
Signed-off-by: Thomas Gleixner

[S390] cputime: fix overflow on 31 bit systems

2009-10-29T14:05:13+00:00

The cputime_to_msecs / cputime_to_clock_t and cputime64_to_clock_t
cause fixpoint divide exceptions if the cputime is too large.
On a machine that collected 49.7 days worth of idle time reading
from /proc/stat will generate oopses like this:

Kernel BUG at 001b0c92 [verbose debug info unavailable]
fixpoint divide exception: 0009 [#13] SMP
Modules linked in: ipv6
CPU: 1 Tainted: G      D   2.6.27.10 #5
Process cat (pid: 21352, task: 1fb34138, ksp: 1d2a3d98)
Krnl PSW : 070c2000 801b0c92 (show_stat+0x2ca/0x68c)
           R:0 T:1 IO:1 EX:1 Key:0 M:1 W:0 P:0 AS:0 CC:2 PM:0
Krnl GPRS: 00000001 00001388 00000bb8 0015d2a1
           00000000 00000000 000003e8 0001fd91
           00000000 00000000 0000129d eecd2ff0
           1cc533b9 0036f780 801b0bce 1d2a3cc0
Krnl Code: 801b0c86: f18890abf198       mvo     171(9,%r9),408(9,%r15)
           801b0c8c: 98abf170           lm      %r10,%r11,368(%r15)
           801b0c90: 1da1               dr      %r10,%r1
          >801b0c92: 90abf170           stm     %r10,%r11,368(%r15)
           801b0c96: 98abf190           lm      %r10,%r11,400(%r15)
           801b0c9a: 1da1               dr      %r10,%r1
           801b0c9c: 90abf190           stm     %r10,%r11,400(%r15)
           801b0ca0: 18a3               lr      %r10,%r3
Call Trace:
([<00000000001b09f4>] show_stat+0x2c/0x68c)
 [<000000000018dcee>] seq_read+0xb2/0x364
 [<00000000001a9980>] proc_reg_read+0x68/0x98
 [<00000000001705ee>] vfs_read+0x6e/0xe8
 [<0000000000170732>] sys_read+0x36/0x78
 [<000000000010f750>] sysc_do_restart+0x12/0x16
 [<0000000077f3ad6a>] 0x77f3ad6a
 <4>---[ end trace 1436ea9559d3de9e ]---

Reported-by: Mike Frysinger 
Signed-off-by: Martin Schwidefsky

cputime: Optimize jiffies_to_cputime(1)

2009-08-03T12:48:36+00:00

For powerpc with CONFIG_VIRT_CPU_ACCOUNTING
jiffies_to_cputime(1) is not compile time constant and run time
calculations are quite expensive. To optimize we use
precomputed value. For all other architectures is is
preprocessor definition.

Signed-off-by: Stanislaw Gruszka 
Acked-by: Peter Zijlstra 
Acked-by: Thomas Gleixner 
Cc: Oleg Nesterov 
Cc: Andrew Morton 
Cc: Paul Mackerras 
Cc: Benjamin Herrenschmidt 
LKML-Reference: <1248862529-6063-5-git-send-email-sgruszka@redhat.com>
Signed-off-by: Ingo Molnar

[S390] lockless idle time accounting

2009-06-22T10:08:23+00:00

Replace the spinlock used in the idle time accounting with a sequence
counter mechanism analog to seqlock.

Signed-off-by: Martin Schwidefsky

[S390] merge cpu.h into cputime.h

2009-06-12T08:27:29+00:00

All definition in cpu.h have to do with cputime accounting. Move
them to cputime.h and remove the header file.

Signed-off-by: Martin Schwidefsky