driver/gator_events_sched.c

   1 /**
   2  * Copyright (C) ARM Limited 2010-2012. All rights reserved.
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License version 2 as
   6  * published by the Free Software Foundation.
   7  *
   8  */
   9
  10 #include "gator.h"
  11 #include <trace/events/sched.h>
  12
  13 #define SCHED_SWITCH    0
  14 #define SCHED_TOTAL             (SCHED_SWITCH+1)
  15
  16 static ulong sched_switch_enabled;
  17 static ulong sched_switch_key;
  18 static DEFINE_PER_CPU(int[SCHED_TOTAL], schedCnt);
  19 static DEFINE_PER_CPU(int[SCHED_TOTAL * 2], schedGet);
  20
  21 #if LINUX_VERSION_CODE < KERNEL_VERSION(2, 6, 35)
  22 GATOR_DEFINE_PROBE(sched_switch, TP_PROTO(struct rq *rq, struct task_struct *prev, struct task_struct *next))
  23 #else
  24 GATOR_DEFINE_PROBE(sched_switch, TP_PROTO(struct task_struct *prev, struct task_struct *next))
  25 #endif
  26 {
  27         unsigned long flags;
  28
  29         // disable interrupts to synchronize with gator_events_sched_read()
  30         // spinlocks not needed since percpu buffers are used
  31         local_irq_save(flags);
  32         per_cpu(schedCnt, smp_processor_id())[SCHED_SWITCH]++;
  33         local_irq_restore(flags);
  34 }
  35
  36 static int gator_events_sched_create_files(struct super_block *sb, struct dentry *root)
  37 {
  38         struct dentry *dir;
  39
  40         /* switch */
  41         dir = gatorfs_mkdir(sb, root, "Linux_sched_switch");
  42         if (!dir) {
  43                 return -1;
  44         }
  45         gatorfs_create_ulong(sb, dir, "enabled", &sched_switch_enabled);
  46         gatorfs_create_ro_ulong(sb, dir, "key", &sched_switch_key);
  47
  48         return 0;
  49 }
  50
  51 static int gator_events_sched_start(void)
  52 {
  53         // register tracepoints
  54         if (sched_switch_enabled)
  55                 if (GATOR_REGISTER_TRACE(sched_switch))
  56                         goto sched_switch_exit;
  57         pr_debug("gator: registered scheduler event tracepoints\n");
  58
  59         return 0;
  60
  61         // unregister tracepoints on error
  62 sched_switch_exit:
  63         pr_err("gator: scheduler event tracepoints failed to activate, please verify that tracepoints are enabled in the linux kernel\n");
  64
  65         return -1;
  66 }
  67
  68 static void gator_events_sched_stop(void)
  69 {
  70         if (sched_switch_enabled)
  71                 GATOR_UNREGISTER_TRACE(sched_switch);
  72         pr_debug("gator: unregistered scheduler event tracepoints\n");
  73
  74         sched_switch_enabled = 0;
  75 }
  76
  77 static int gator_events_sched_read(int **buffer)
  78 {
  79         unsigned long flags;
  80         int len, value;
  81         int cpu = smp_processor_id();
  82
  83         len = 0;
  84         if (sched_switch_enabled) {
  85                 local_irq_save(flags);
  86                 value = per_cpu(schedCnt, cpu)[SCHED_SWITCH];
  87                 per_cpu(schedCnt, cpu)[SCHED_SWITCH] = 0;
  88                 local_irq_restore(flags);
  89                 per_cpu(schedGet, cpu)[len++] = sched_switch_key;
  90                 per_cpu(schedGet, cpu)[len++] = value;
  91         }
  92
  93         if (buffer)
  94                 *buffer = per_cpu(schedGet, cpu);
  95
  96         return len;
  97 }
  98
  99 static struct gator_interface gator_events_sched_interface = {
 100         .create_files = gator_events_sched_create_files,
 101         .start = gator_events_sched_start,
 102         .stop = gator_events_sched_stop,
 103         .read = gator_events_sched_read,
 104 };
 105
 106 int gator_events_sched_init(void)
 107 {
 108         sched_switch_enabled = 0;
 109
 110         sched_switch_key = gator_events_get_key();
 111
 112         return gator_events_install(&gator_events_sched_interface);
 113 }
 114 gator_events_init(gator_events_sched_init);