Commit Graph

10 Commits

Author SHA1 Message Date
Li Zefan e36673ec51 tracing: Fix lockdep warning in global_clock()
# echo 1 > events/enable
 # echo global > trace_clock

------------[ cut here ]------------
WARNING: at kernel/lockdep.c:3162 check_flags+0xb2/0x190()
...
---[ end trace 3f86734a89416623 ]---
possible reason: unannotated irqs-on.
...

There's no reason to use the raw_local_irq_save() in trace_clock_global.
The local_irq_save() version is fine, and does not cause the bug in lockdep.

Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
LKML-Reference: <4BA97FA1.7030606@cn.fujitsu.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2010-03-29 15:16:44 -04:00
Frederic Weisbecker ae1f30384b tracing: Include irqflags headers from trace clock
trace_clock.c includes spinlock.h, which ends up including
asm/system.h, which in turn includes linux/irqflags.h in x86.

So the definition of raw_local_irq_save is luckily covered there,
but this is not the case in parisc:

   tip/kernel/trace/trace_clock.c:86: error: implicit declaration of function 'raw_local_irq_save'
   tip/kernel/trace/trace_clock.c:112: error: implicit declaration of function 'raw_local_irq_restore'

We need to include linux/irqflags.h directly from trace_clock.c
to avoid such build error.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Robert Richter <robert.richter@amd.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2010-02-28 19:45:01 +01:00
Thomas Gleixner 0199c4e68d locking: Convert __raw_spin* functions to arch_spin*
Name space cleanup. No functional change.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: David S. Miller <davem@davemloft.net>
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: linux-arch@vger.kernel.org
2009-12-14 23:55:32 +01:00
Thomas Gleixner edc35bd72e locking: Rename __RAW_SPIN_LOCK_UNLOCKED to __ARCH_SPIN_LOCK_UNLOCKED
Further name space cleanup. No functional change

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: David S. Miller <davem@davemloft.net>
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: linux-arch@vger.kernel.org
2009-12-14 23:55:32 +01:00
Thomas Gleixner 445c89514b locking: Convert raw_spinlock to arch_spinlock
The raw_spin* namespace was taken by lockdep for the architecture
specific implementations. raw_spin_* would be the ideal name space for
the spinlocks which are not converted to sleeping locks in preempt-rt.

Linus suggested to convert the raw_ to arch_ locks and cleanup the
name space instead of using an artifical name like core_spin,
atomic_spin or whatever

No functional change.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: David S. Miller <davem@davemloft.net>
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: linux-arch@vger.kernel.org
2009-12-14 23:55:32 +01:00
Steven Rostedt 8b2a5dac78 tracing: do not disable interrupts for trace_clock_local
Disabling interrupts in trace_clock_local takes quite a performance
hit to the recording of traces. Using perf top we see:

------------------------------------------------------------------------------
   PerfTop:     244 irqs/sec  kernel:100.0% [1000Hz cpu-clock-msecs],  (all, 4 CPUs)
------------------------------------------------------------------------------

             samples    pcnt   kernel function
             _______   _____   _______________

             2842.00 - 40.4% : trace_clock_local
             1043.00 - 14.8% : rb_reserve_next_event
              784.00 - 11.1% : ring_buffer_lock_reserve
              600.00 -  8.5% : __rb_reserve_next
              579.00 -  8.2% : rb_end_commit
              440.00 -  6.3% : ring_buffer_unlock_commit
              290.00 -  4.1% : ring_buffer_producer_thread 	[ring_buffer_benchmark]
              155.00 -  2.2% : debug_smp_processor_id
              117.00 -  1.7% : trace_recursive_unlock
              103.00 -  1.5% : ring_buffer_event_data
               28.00 -  0.4% : do_gettimeofday
               22.00 -  0.3% : _spin_unlock_irq
               14.00 -  0.2% : native_read_tsc
               11.00 -  0.2% : getnstimeofday

Where trace_clock_local is 40% of the tracing, and the time for recording
a trace according to ring_buffer_benchmark is 210ns. After converting
the interrupts to preemption disabling we have from perf top:

------------------------------------------------------------------------------
   PerfTop:    1084 irqs/sec  kernel:99.9% [1000Hz cpu-clock-msecs],  (all, 4 CPUs)
------------------------------------------------------------------------------

             samples    pcnt   kernel function
             _______   _____   _______________

             1277.00 - 16.8% : native_read_tsc
             1148.00 - 15.1% : rb_reserve_next_event
              896.00 - 11.8% : ring_buffer_lock_reserve
              688.00 -  9.1% : __rb_reserve_next
              664.00 -  8.8% : rb_end_commit
              563.00 -  7.4% : ring_buffer_unlock_commit
              508.00 -  6.7% : _spin_unlock_irq
              365.00 -  4.8% : debug_smp_processor_id
              321.00 -  4.2% : trace_clock_local
              303.00 -  4.0% : ring_buffer_producer_thread 	[ring_buffer_benchmark]
              273.00 -  3.6% : native_sched_clock
              122.00 -  1.6% : trace_recursive_unlock
              113.00 -  1.5% : sched_clock
              101.00 -  1.3% : ring_buffer_event_data
               53.00 -  0.7% : tick_nohz_stop_sched_tick

Where trace_clock_local drops from 40% to only taking 4% of the total time.
The trace time also goes from 210ns down to 179ns (31ns).

I talked with Peter Zijlstra about the impact that sched_clock may have
without having interrupts disabled, and he told me that if a timer interrupt
comes in, sched_clock may report a wrong time.

Balancing a seldom incorrect timestamp with a 15% performance boost, I'll
take the performance boost.

Acked-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2009-11-11 23:38:33 -05:00
Steven Rostedt 6ca6cca31d tracing: optimize global_trace_clock cachelines
The prev_trace_clock_time is only read or written to when the
trace_clock_lock is taken. For better perfomance, they
should share the same cache line.

Reported-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2009-09-15 12:24:22 -04:00
Dmitri Vorobiev b8b9426533 tracing: fix four sparse warnings
Impact: cleanup.

This patch fixes the following sparse warnings:

 kernel/trace/trace.c:385:9: warning: symbol 'trace_seq_to_buffer' was
 not declared. Should it be static?

 kernel/trace/trace_clock.c:29:13: warning: symbol 'trace_clock_local'
 was not declared. Should it be static?

 kernel/trace/trace_clock.c:54:13: warning: symbol 'trace_clock' was not
 declared. Should it be static?

 kernel/trace/trace_clock.c:74:13: warning: symbol 'trace_clock_global'
 was not declared. Should it be static?

Signed-off-by: Dmitri Vorobiev <dmitri.vorobiev@movial.com>
LKML-Reference: <1237741871-5827-4-git-send-email-dmitri.vorobiev@movial.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-03-22 18:16:54 +01:00
Peter Zijlstra 6cc3c6e12b trace_clock: fix preemption bug
Using the function_graph tracer in recent kernels generates a spew of
preemption BUGs. Fix this by not requiring trace_clock_local() users
to disable preemption themselves.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-03-10 20:03:01 +01:00
Ingo Molnar 14131f2f98 tracing: implement trace_clock_*() APIs
Impact: implement new tracing timestamp APIs

Add three trace clock variants, with differing scalability/precision
tradeoffs:

 -   local: CPU-local trace clock
 -  medium: scalable global clock with some jitter
 -  global: globally monotonic, serialized clock

Make the ring-buffer use the local trace clock internally.

Acked-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-02-26 18:44:06 +01:00