src/patches/suse-2.6.27.25/patches.trace/lttng-instrumentation-irq.patch

   1 From: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
   2 Subject: LTTng instrumentation - irq
   3
   4 Original patch header:
   5   LTTng instrumentation - irq
   6
   7   Instrumentation of IRQ related events : irq, softirq, tasklet entry and exit and
   8   softirq "raise" events.
   9
  10   It allows tracers to perform latency analysis on those various types of
  11   interrupts and to detect interrupts with max/min/avg duration. It helps
  12   detecting driver or hardware problems which cause an ISR to take ages to
  13   execute. It has been shown to be the case with bogus hardware causing an mmio
  14   read to take a few milliseconds.
  15
  16   Those tracepoints are used by LTTng.
  17
  18   About the performance impact of tracepoints (which is comparable to markers),
  19   even without immediate values optimizations, tests done by Hideo Aoki on ia64
  20   show no regression. His test case was using hackbench on a kernel where
  21   scheduler instrumentation (about 5 events in code scheduler code) was added.
  22   See the "Tracepoints" patch header for performance result detail.
  23
  24   Changelog:
  25   - Add retval as irq_exit argument.
  26
  27   Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
  28   CC: Thomas Gleixner <tglx@linutronix.de>
  29   CC: Russell King <rmk+lkml@arm.linux.org.uk>
  30   CC: Masami Hiramatsu <mhiramat@redhat.com>
  31   CC: 'Peter Zijlstra' <peterz@infradead.org>
  32   CC: "Frank Ch. Eigler" <fche@redhat.com>
  33   CC: 'Ingo Molnar' <mingo@elte.hu>
  34   CC: 'Hideo AOKI' <haoki@redhat.com>
  35   CC: Takashi Nishiie <t-nishiie@np.css.fujitsu.com>
  36   CC: 'Steven Rostedt' <rostedt@goodmis.org>
  37   CC: Eduard - Gabriel Munteanu <eduard.munteanu@linux360.ro>
  38
  39 Acked-by: Jan Blunck <jblunck@suse.de>
  40 ---
  41 ---
  42  include/trace/irq.h |   36 ++++++++++++++++++++++++++++++++++++
  43  kernel/irq/handle.c |    6 ++++++
  44  kernel/softirq.c    |    8 ++++++++
  45  3 files changed, 50 insertions(+)
  46
  47 --- /dev/null
  48 +++ b/include/trace/irq.h
  49 @@ -0,0 +1,36 @@
  50 +#ifndef _TRACE_IRQ_H
  51 +#define _TRACE_IRQ_H
  52 +
  53 +#include <linux/kdebug.h>
  54 +#include <linux/interrupt.h>
  55 +#include <linux/tracepoint.h>
  56 +
  57 +DEFINE_TRACE(irq_entry,
  58 +       TPPROTO(unsigned int id, struct pt_regs *regs),
  59 +       TPARGS(id, regs));
  60 +DEFINE_TRACE(irq_exit,
  61 +       TPPROTO(irqreturn_t retval),
  62 +       TPARGS(retval));
  63 +DEFINE_TRACE(irq_softirq_entry,
  64 +       TPPROTO(struct softirq_action *h, struct softirq_action *softirq_vec),
  65 +       TPARGS(h, softirq_vec));
  66 +DEFINE_TRACE(irq_softirq_exit,
  67 +       TPPROTO(struct softirq_action *h, struct softirq_action *softirq_vec),
  68 +       TPARGS(h, softirq_vec));
  69 +DEFINE_TRACE(irq_softirq_raise,
  70 +       TPPROTO(unsigned int nr),
  71 +       TPARGS(nr));
  72 +DEFINE_TRACE(irq_tasklet_low_entry,
  73 +       TPPROTO(struct tasklet_struct *t),
  74 +       TPARGS(t));
  75 +DEFINE_TRACE(irq_tasklet_low_exit,
  76 +       TPPROTO(struct tasklet_struct *t),
  77 +       TPARGS(t));
  78 +DEFINE_TRACE(irq_tasklet_high_entry,
  79 +       TPPROTO(struct tasklet_struct *t),
  80 +       TPARGS(t));
  81 +DEFINE_TRACE(irq_tasklet_high_exit,
  82 +       TPPROTO(struct tasklet_struct *t),
  83 +       TPARGS(t));
  84 +
  85 +#endif
  86 --- a/kernel/irq/handle.c
  87 +++ b/kernel/irq/handle.c
  88 @@ -15,6 +15,7 @@
  89  #include <linux/random.h>
  90  #include <linux/interrupt.h>
  91  #include <linux/kernel_stat.h>
  92 +#include <trace/irq.h>
  93
  94  #include "internals.h"
  95
  96 @@ -130,6 +131,9 @@ irqreturn_t handle_IRQ_event(unsigned in
  97  {
  98         irqreturn_t ret, retval = IRQ_NONE;
  99         unsigned int status = 0;
 100 +       struct pt_regs *regs = get_irq_regs();
 101 +
 102 +       trace_irq_entry(irq, regs);
 103
 104         handle_dynamic_tick(action);
 105
 106 @@ -148,6 +152,8 @@ irqreturn_t handle_IRQ_event(unsigned in
 107                 add_interrupt_randomness(irq);
 108         local_irq_disable();
 109
 110 +       trace_irq_exit(retval);
 111 +
 112         return retval;
 113  }
 114
 115 --- a/kernel/softirq.c
 116 +++ b/kernel/softirq.c
 117 @@ -21,6 +21,7 @@
 118  #include <linux/rcupdate.h>
 119  #include <linux/smp.h>
 120  #include <linux/tick.h>
 121 +#include <trace/irq.h>
 122
 123  #include <asm/irq.h>
 124  /*
 125 @@ -205,7 +206,9 @@ restart:
 126
 127         do {
 128                 if (pending & 1) {
 129 +                       trace_irq_softirq_entry(h, softirq_vec);
 130                         h->action(h);
 131 +                       trace_irq_softirq_exit(h, softirq_vec);
 132                         rcu_bh_qsctr_inc(cpu);
 133                 }
 134                 h++;
 135 @@ -297,6 +300,7 @@ void irq_exit(void)
 136   */
 137  inline void raise_softirq_irqoff(unsigned int nr)
 138  {
 139 +       trace_irq_softirq_raise(nr);
 140         __raise_softirq_irqoff(nr);
 141
 142         /*
 143 @@ -383,7 +387,9 @@ static void tasklet_action(struct softir
 144                         if (!atomic_read(&t->count)) {
 145                                 if (!test_and_clear_bit(TASKLET_STATE_SCHED, &t->state))
 146                                         BUG();
 147 +                               trace_irq_tasklet_low_entry(t);
 148                                 t->func(t->data);
 149 +                               trace_irq_tasklet_low_exit(t);
 150                                 tasklet_unlock(t);
 151                                 continue;
 152                         }
 153 @@ -418,7 +424,9 @@ static void tasklet_hi_action(struct sof
 154                         if (!atomic_read(&t->count)) {
 155                                 if (!test_and_clear_bit(TASKLET_STATE_SCHED, &t->state))
 156                                         BUG();
 157 +                               trace_irq_tasklet_high_entry(t);
 158                                 t->func(t->data);
 159 +                               trace_irq_tasklet_high_exit(t);
 160                                 tasklet_unlock(t);
 161                                 continue;
 162                         }