linux.git/arch/powerpc/kernel/time.c, branch v2.6.26

ntp: rename TICK_LENGTH_SHIFT to NTP_SCALE_SHIFT

2008-05-01T15:03:59+00:00

As TICK_LENGTH_SHIFT is used for more than just the tick length, the name
isn't quite approriate anymore, so this renames it to NTP_SCALE_SHIFT.

Signed-off-by: Roman Zippel 
Cc: john stultz 
Cc: Thomas Gleixner 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

ntp: increase time_freq resolution

2008-05-01T15:03:58+00:00

This changes time_freq to a 64bit value and makes it static (the only outside
user had no real need to modify it).  Intermediate values were already 64bit,
so the change isn't that big, but it saves a little in shifts by replacing
SHIFT_NSEC with TICK_LENGTH_SHIFT.  PPM_SCALE is then used to convert between
user space and kernel space representation.

Signed-off-by: Roman Zippel 
Cc: john stultz 
Cc: Thomas Gleixner 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

taskstats scaled time cleanup

2008-02-06T18:41:00+00:00

This moves the ability to scale cputime into generic code.  This allows us
to fix the issue in kernel/timer.c (noticed by Balbir) where we could only
add an unscaled value to the scaled utime/stime.

This adds a cputime_to_scaled function.  As before, the POWERPC version
does the scaling based on the last SPURR/PURR ratio calculated.  The
generic and s390 (only other arch to implement asm/cputime.h) versions are
both NOPs.

Also moves the SPURR and PURR snapshots closer.

Signed-off-by: Michael Neuling 
Cc: Jay Lan 
Cc: Paul Mackerras 
Cc: Benjamin Herrenschmidt 
Cc: Heiko Carstens 
Cc: Martin Schwidefsky 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[POWERPC] Implement arch disable/enable irq hooks.

2007-12-21T11:13:35+00:00

These hooks ensure that a decrementer interrupt is not pending when
suspending; otherwise, problems may occur on 6xx/7xx/7xxx-based
systems (except for powermacs, which use a separate suspend path).
For example, with deep sleep on the 831x, a pending decrementer will
cause a system freeze because the SoC thinks the decrementer interrupt
would have woken the system, but the core must have interrupts
disabled due to the setup required for deep sleep.

Changed via-pmu.c to use the new ppc_md hooks, and made the arch_*
functions call the generic_* functions unconditionally.  -- paulus

Signed-off-by: Scott Wood 
Signed-off-by: Paul Mackerras

[POWERPC] Optimize account_system_vtime

2007-12-20T05:15:46+00:00

We have multiple calls to has_feature being inlined, but gcc can't
be sure that the store via get_paca() doesn't alias the path to
cur_cpu_spec->feature.

Reorder to put the calls to read_purr and read_spurr adjacent to each
other.  To add a sense of consistency, reorder the remaining lines to
perform parallel steps on purr and scaled purr of each line instead of
calculating and then using one value before going on to the next.

In addition, we can tell gcc that no SPURR means no PURR.  The test is
completely hidden in the PURR case, and in the !PURR case the second test
is eliminated resulting in the simple register copy in the out-of-line
branch.

Further, gcc sees get_paca()->system_time referenced several times and
allocates a register to address it (shadowing r13) instead of caching its
value.  Reading into a local varable saves the shadow of r13 and removes
a potentially duplicate load (between the nested if and its parent).

Signed-off-by: Milton Miller 
Signed-off-by: Paul Mackerras

[POWERPC] Depend on ->initialized in calc_steal_time

2007-12-20T05:15:43+00:00

If CPU_FTR_PURR is not set, we will never set cpu_purr_data->initialized.
Checking via __get_cpu_var on 64 bit avoids one dependent load compared
to cpu_has_feature in the not-present case, and is always required when
it is present.  The code is under CONFIG_VIRT_CPU_ACCOUNTING so 32 bit
will not be affected.

Signed-off-by: Milton Miller 
Signed-off-by: Paul Mackerras

[POWERPC] Timer interrupt: use a struct for two per_cpu varables

2007-12-20T05:15:41+00:00

timer_interrupt() was calculating per_cpu_offset several times, having to
start from the toc because of potential aliasing issues.

Placing both decrementer per_cpu varables in a struct and calculating
the address once with __get_cpu_var results in better code on both 32
and 64 bit.

Signed-off-by: Milton Miller 
Signed-off-by: Paul Mackerras

[POWERPC] Use __get_cpu_var in time.c

2007-12-20T05:15:39+00:00

Use __get_cpu_var(x) instead of per_cpu(x, smp_processor_id()), as it
is optimized on ppc64 to access the current cpu's per-cpu offset directly;
it's local_paca.offset instead of TOC->paca[local_paca->processor_id].offset.

This is the trivial portion, two functions with one use each.

Signed-off-by: Milton Miller 
Signed-off-by: Paul Mackerras

[POWERPC] init_decrementer_clockevent can be static __init

2007-12-20T05:15:37+00:00

as its only called from time_init, which is __init.

Also remove unneeded forward declaration.

Signed-off-by: Milton Miller 
Signed-off-by: Paul Mackerras

[POWERPC] Fix possible division by zero in scaled time accounting

2007-11-20T05:10:28+00:00

If we get no user time and no system time allocated since the last
account_system_vtime, the system to user time ratio estimate can end
up dividing by zero.

This was causing a problem noticed by Balbir Singh.

Signed-off-by: Michael Neuling 
Signed-off-by: Paul Mackerras