linux-toradex.git/arch/microblaze/kernel/process.c, branch v3.3.5

nohz: Remove tick_nohz_idle_enter_norcu() / tick_nohz_idle_exit_norcu()

2011-12-11T18:31:57+00:00

Those two APIs were provided to optimize the calls of
tick_nohz_idle_enter() and rcu_idle_enter() into a single
irq disabled section. This way no interrupt happening in-between would
needlessly process any RCU job.

Now we are talking about an optimization for which benefits
have yet to be measured. Let's start simple and completely decouple
idle rcu and dyntick idle logics to simplify.

Signed-off-by: Frederic Weisbecker 
Cc: Ingo Molnar 
Cc: Thomas Gleixner 
Cc: Peter Zijlstra 
Reviewed-by: Josh Triplett 
Signed-off-by: Paul E. McKenney

nohz: Allow rcu extended quiescent state handling seperately from tick stop

2011-12-11T18:31:36+00:00

It is assumed that rcu won't be used once we switch to tickless
mode and until we restart the tick. However this is not always
true, as in x86-64 where we dereference the idle notifiers after
the tick is stopped.

To prepare for fixing this, add two new APIs:
tick_nohz_idle_enter_norcu() and tick_nohz_idle_exit_norcu().

If no use of RCU is made in the idle loop between
tick_nohz_enter_idle() and tick_nohz_exit_idle() calls, the arch
must instead call the new *_norcu() version such that the arch doesn't
need to call rcu_idle_enter() and rcu_idle_exit().

Otherwise the arch must call tick_nohz_enter_idle() and
tick_nohz_exit_idle() and also call explicitly:

- rcu_idle_enter() after its last use of RCU before the CPU is put
to sleep.
- rcu_idle_exit() before the first use of RCU after the CPU is woken
up.

Signed-off-by: Frederic Weisbecker 
Cc: Mike Frysinger 
Cc: Guan Xuetao 
Cc: David Miller 
Cc: Chris Metcalf 
Cc: Hans-Christian Egtvedt 
Cc: Ralf Baechle 
Cc: Paul E. McKenney 
Cc: Ingo Molnar 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: H. Peter Anvin 
Cc: Russell King 
Cc: Paul Mackerras 
Cc: Heiko Carstens 
Cc: Paul Mundt 
Signed-off-by: Paul E. McKenney

nohz: Separate out irq exit and idle loop dyntick logic

2011-12-11T18:31:35+00:00

The tick_nohz_stop_sched_tick() function, which tries to delay
the next timer tick as long as possible, can be called from two
places:

- From the idle loop to start the dytick idle mode
- From interrupt exit if we have interrupted the dyntick
idle mode, so that we reprogram the next tick event in
case the irq changed some internal state that requires this
action.

There are only few minor differences between both that
are handled by that function, driven by the ts->inidle
cpu variable and the inidle parameter. The whole guarantees
that we only update the dyntick mode on irq exit if we actually
interrupted the dyntick idle mode, and that we enter in RCU extended
quiescent state from idle loop entry only.

Split this function into:

- tick_nohz_idle_enter(), which sets ts->inidle to 1, enters
dynticks idle mode unconditionally if it can, and enters into RCU
extended quiescent state.

- tick_nohz_irq_exit() which only updates the dynticks idle mode
when ts->inidle is set (ie: if tick_nohz_idle_enter() has been called).

To maintain symmetry, tick_nohz_restart_sched_tick() has been renamed
into tick_nohz_idle_exit().

This simplifies the code and micro-optimize the irq exit path (no need
for local_irq_save there). This also prepares for the split between
dynticks and rcu extended quiescent state logics. We'll need this split to
further fix illegal uses of RCU in extended quiescent states in the idle
loop.

Signed-off-by: Frederic Weisbecker 
Cc: Mike Frysinger 
Cc: Guan Xuetao 
Cc: David Miller 
Cc: Chris Metcalf 
Cc: Hans-Christian Egtvedt 
Cc: Ralf Baechle 
Cc: Paul E. McKenney 
Cc: Ingo Molnar 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: H. Peter Anvin 
Cc: Russell King 
Cc: Paul Mackerras 
Cc: Heiko Carstens 
Cc: Paul Mundt 
Signed-off-by: Paul E. McKenney 
Reviewed-by: Josh Triplett

microblaze: Remove __ARCH_WANT_INTERRUPTS_ON_CTXSW usage

2011-10-14T10:28:42+00:00

As far as I can tell the only reason microblaze has
__ARCH_WANT_INTERRUPTS_ON_CTXSW is because it initializes new task state
with interrupts enabled so that on switch_to() interrupts get enabled.

So change copy_thread() to clear MSR_IE instead of set it, this will
ensure switch_to() will always keep IRQs disabled.

The scheduler will disable IRQs when taking rq->lock in schedule() and
enable IRQs in finish_lock_switch() after its done its magic.

This leaves ARM the only __ARCH_WANT_INTERRUPTS_ON_CTXSW user.

Signed-off-by: Peter Zijlstra 
Signed-off-by: Michal Simek

microblaze: exec: Remove redundant set_fs(USER_DS)

2011-07-25T07:07:45+00:00

The address limit is already set in flush_old_exec() so this
set_fs(USER_DS) is redundant.

Signed-off-by: Mathias Krause

microblaze: Remove r0_ram pointer and PTO alignment

2011-03-09T07:09:54+00:00

r0_ram pool was used for saving/restoring register
content if hw exception happen. This poll was replaced by
pt_pool_space with PT_SIZE size.
Based on this change SAVE_STATE_ARG_SPACE was removed which
caused that PTO offset is zero that's why is also removed.

r0_ram space was used as scratchpad by v850. In early
Microblaze Linux developing phase was this part of code
blindly copied.

Signed-off-by: Michal Simek

microblaze: Do not trace cpu_relax function

2010-08-04T08:22:36+00:00

IRQsoff tracer requires to protect cpu_idle function
to get correct timing report.

Signed-off-by: Michal Simek

microblaze: Adding likely macros

2010-04-01T06:38:24+00:00

On the base on GCOV analytics is helpful to add likely/unlikely
macros.

Signed-off-by: Michal Simek

microblaze: Remove segment.h

2010-04-01T06:38:19+00:00

I would like to use asm-generic uaccess.h where are segment
macros defined. This is just first step.

Signed-off-by: Michal Simek

microblaze: Move cache macro from cache.h to cacheflush.h

2009-12-14T07:45:00+00:00

Signed-off-by: Michal Simek