./cyclictest -p 80 -t5 -n  => Cyclic test is failing after 6Lack iterations
T: 0 ( 1364) P:99 I:1000 C: 668664 Min:      3 Act:    5 Avg:   11 Max:  100116

After analyzing the trace log , we observed the sudden change in
latency due to calling of fpsimd_preserve_current_state function.

Line 149766:     ntpd-925     1....1.. 512046976us :
fpsimd_preserve_current_state <-do_signal
Line 149768:     ntpd-925     1....1.. 512046977us : preempt_count_add
<-fpsimd_preserve_current_state
Line 149770:     ntpd-925     1....2.. 512046978us : preempt_count_sub
<-fpsimd_preserve_current_state

.......
Line 163170: cyclicte-964     0.....11 512065181us :
tracing_mark_write: hit latency threshold (98383 > 500)


Thanks and regards,
Ayyappa.Ch

...

On Thu, May 7, 2015 at 1:08 AM, Anders Roxell [off-list ref] wrote:

On 2015-05-01 20:59, Ayyappa Ch wrote:

quoted

Floating point operations in arm64 should not disable preempt .

I thought that I would see a problem if I ran a floating point
workload and cyclictest at the same time but I don't.

Can you please provide me some more details on how I can reproduce the
problem?

Cheers,
Anders

quoted

Activating realtime features with below code.

From e6a5fce9b3b55f48656240036a9354a0997c2907 Mon Sep 17 00:00:00 2001
From: Ayyappa Ch <redacted>
Date: Tue, 28 Apr 2015 11:53:00 +0530
Subject: [PATCH ] floating point realtime fix

---
 arch/arm64/kernel/fpsimd.c | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/arch/arm64/kernel/fpsimd.c b/arch/arm64/kernel/fpsimd.c
index 2438497..3dca156 100644
--- a/arch/arm64/kernel/fpsimd.c
+++ b/arch/arm64/kernel/fpsimd.c

@@ -166,10 +166,10 @@ void fpsimd_flush_thread(void)
  */
 void fpsimd_preserve_current_state(void)
 {
- preempt_disable();
+ migrate_disable();
  if (!test_thread_flag(TIF_FOREIGN_FPSTATE))
  fpsimd_save_state(&current->thread.fpsimd_state);
- preempt_enable();
+ migrate_enable();
 }

 /*

@@ -179,7 +179,7 @@ void fpsimd_preserve_current_state(void)
  */
 void fpsimd_restore_current_state(void)
 {
- preempt_disable();
+ migrate_disable();
  if (test_and_clear_thread_flag(TIF_FOREIGN_FPSTATE)) {
  struct fpsimd_state *st = &current->thread.fpsimd_state;

@@ -187,7 +187,7 @@ void fpsimd_restore_current_state(void)
  this_cpu_write(fpsimd_last_state, st);
  st->cpu = smp_processor_id();
  }
- preempt_enable();
+ migrate_enable();
 }

 /*

@@ -197,7 +197,7 @@ void fpsimd_restore_current_state(void)
  */
 void fpsimd_update_current_state(struct fpsimd_state *state)
 {
- preempt_disable();
+ migrate_disable();
  fpsimd_load_state(state);
  if (test_and_clear_thread_flag(TIF_FOREIGN_FPSTATE)) {
  struct fpsimd_state *st = &current->thread.fpsimd_state;

@@ -205,7 +205,7 @@ void fpsimd_update_current_state(struct fpsimd_state *state)
  this_cpu_write(fpsimd_last_state, st);
  st->cpu = smp_processor_id();
  }
- preempt_enable();
+ migrate_enable();
 }

 /*

@@ -239,7 +239,7 @@ void kernel_neon_begin_partial(u32 num_regs)
  * that there is no longer userland FPSIMD state in the
  * registers.
  */
- preempt_disable();
+ migrate_disable();
  if (current->mm &&
     !test_and_set_thread_flag(TIF_FOREIGN_FPSTATE))
  fpsimd_save_state(&current->thread.fpsimd_state);

@@ -255,7 +255,7 @@ void kernel_neon_end(void)
  in_irq() ? &hardirq_fpsimdstate : &softirq_fpsimdstate);
  fpsimd_load_partial_state(s);
  } else {
- preempt_enable();
+ migrate_enable();
  }
 }
 EXPORT_SYMBOL(kernel_neon_end);

On Fri, May 1, 2015 at 1:03 PM, Ayyappa Ch [off-list ref] wrote:

quoted

Following Anders Roxell  patch on "Enable PREEMPT_RT_FULL" , observed
one issue with Cyclic test while running floating point operations. So
, modified below changes for that.

From e6a5fce9b3b55f48656240036a9354a0997c2907 Mon Sep 17 00:00:00 2001
From: Ayyappa Ch <redacted>
Date: Tue, 28 Apr 2015 11:53:00 +0530
Subject: [PATCH ] floating point realtime fix

---
 arch/arm64/kernel/fpsimd.c | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/arch/arm64/kernel/fpsimd.c b/arch/arm64/kernel/fpsimd.c
index 2438497..3dca156 100644
--- a/arch/arm64/kernel/fpsimd.c
+++ b/arch/arm64/kernel/fpsimd.c

@@ -166,10 +166,10 @@ void fpsimd_flush_thread(void)
  */
 void fpsimd_preserve_current_state(void)
 {
- preempt_disable();
+ migrate_disable();
  if (!test_thread_flag(TIF_FOREIGN_FPSTATE))
  fpsimd_save_state(&current->thread.fpsimd_state);
- preempt_enable();
+ migrate_enable();
 }

 /*

@@ -179,7 +179,7 @@ void fpsimd_preserve_current_state(void)
  */
 void fpsimd_restore_current_state(void)
 {
- preempt_disable();
+ migrate_disable();
  if (test_and_clear_thread_flag(TIF_FOREIGN_FPSTATE)) {
  struct fpsimd_state *st = &current->thread.fpsimd_state;

@@ -187,7 +187,7 @@ void fpsimd_restore_current_state(void)
  this_cpu_write(fpsimd_last_state, st);
  st->cpu = smp_processor_id();
  }
- preempt_enable();
+ migrate_enable();
 }

 /*

@@ -197,7 +197,7 @@ void fpsimd_restore_current_state(void)
  */
 void fpsimd_update_current_state(struct fpsimd_state *state)
 {
- preempt_disable();
+ migrate_disable();
  fpsimd_load_state(state);
  if (test_and_clear_thread_flag(TIF_FOREIGN_FPSTATE)) {
  struct fpsimd_state *st = &current->thread.fpsimd_state;

@@ -205,7 +205,7 @@ void fpsimd_update_current_state(struct fpsimd_state *state)
  this_cpu_write(fpsimd_last_state, st);
  st->cpu = smp_processor_id();
  }
- preempt_enable();
+ migrate_enable();
 }

 /*

@@ -239,7 +239,7 @@ void kernel_neon_begin_partial(u32 num_regs)
  * that there is no longer userland FPSIMD state in the
  * registers.
  */
- preempt_disable();
+ migrate_disable();
  if (current->mm &&
     !test_and_set_thread_flag(TIF_FOREIGN_FPSTATE))
  fpsimd_save_state(&current->thread.fpsimd_state);

@@ -255,7 +255,7 @@ void kernel_neon_end(void)
  in_irq() ? &hardirq_fpsimdstate : &softirq_fpsimdstate);
  fpsimd_load_partial_state(s);
  } else {
- preempt_enable();
+ migrate_enable();
  }
 }
 EXPORT_SYMBOL(kernel_neon_end);
--

1.9.1