Hello Anders Roxell,
Many thanks for your inputs.
But as per my observation after this change , Cyclic test did not failed.
As logs are huge size , sent only to you.
Can you please check the logs and let us know your view ?
Thanks and regards,
Ayyappa.Ch
On Fri, May 8, 2015 at 5:39 AM, Anders Roxell <anders.roxell@xxxxxxxxxx> wrote:
> On 2015-05-07 16:39, Ayyappa Ch wrote:
>> ./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.
>
> I'm still unable to reproduce your problem scenario and from the log
> snippet below I'm not convinced that fpsimd_preserve_current_state is
> the bad guy.
>
>>
>> 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
>
> fpsimd_preserve_current_state seams to return within 2us
>
>>
>> .......
>> Line 163170: cyclicte-964 0.....11 512065181us :
>
> The latency appears to be happening somewhere between the
> fpsimd_preserve_current_state return and the resumption of the cyclictest.
> Whatever cased the latency may have happened in the omitted portion of
> the trace log?
> It may not even have been traceable thread of execution, depending on
> the trace tool that have been used.
> If the part of the trace log that you didn't show doesn't seam to have
> any interesting events then maybe the offending code runs outside of
> scheduler control or never touches any defined trace points.
>
> Cheers,
> Anders
>
>> tracing_mark_write: hit latency threshold (98383 > 500)
>>
>>
>> Thanks and regards,
>> Ayyappa.Ch
>>
>> ...
>>
>> On Thu, May 7, 2015 at 1:08 AM, Anders Roxell <anders.roxell@xxxxxxxxxx> wrote:
>> > On 2015-05-01 20:59, Ayyappa Ch wrote:
>> >> 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
>> >
>> >> Activating realtime features with below code.
>> >>
>> >> From e6a5fce9b3b55f48656240036a9354a0997c2907 Mon Sep 17 00:00:00 2001
>> >> From: Ayyappa Ch <ayyappa.chandolu@xxxxxxx>
>> >> 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(¤t->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 = ¤t->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 = ¤t->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(¤t->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 <ayyappa.ch.linux@xxxxxxxxx> wrote:
>> >> > 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 <ayyappa.chandolu@xxxxxxx>
>> >> > 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(¤t->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 = ¤t->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 = ¤t->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(¤t->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
>
> --
> Anders Roxell
> anders.roxell@xxxxxxxxxx
> M: +46 709 71 42 85 | IRC: roxell
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