driver/gator_events_block.c

   1 /**
   2  * Copyright (C) ARM Limited 2010-2011. 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/block.h>
  12
  13 #define BLOCK_RQ_WR             0
  14 #define BLOCK_RQ_RD             1
  15
  16 #define BLOCK_TOTAL             (BLOCK_RQ_RD+1)
  17
  18 #if LINUX_VERSION_CODE < KERNEL_VERSION(2, 6, 36)
  19 #define EVENTWRITE REQ_RW
  20 #else
  21 #define EVENTWRITE REQ_WRITE
  22 #endif
  23
  24 static ulong block_rq_wr_enabled;
  25 static ulong block_rq_rd_enabled;
  26 static ulong block_rq_wr_key;
  27 static ulong block_rq_rd_key;
  28 static DEFINE_PER_CPU(int[BLOCK_TOTAL], blockCnt);
  29 static DEFINE_PER_CPU(int[BLOCK_TOTAL * 2], blockGet);
  30 static DEFINE_PER_CPU(bool, new_data_avail);
  31
  32 GATOR_DEFINE_PROBE(block_rq_complete, TP_PROTO(struct request_queue *q, struct request *rq))
  33 {
  34         unsigned long flags;
  35         int write, size;
  36         int cpu = smp_processor_id();
  37
  38         if (!rq)
  39                 return;
  40
  41         write = rq->cmd_flags & EVENTWRITE;
  42         size = rq->resid_len;
  43
  44         if (!size)
  45                 return;
  46
  47         // disable interrupts to synchronize with gator_events_block_read()
  48         // spinlocks not needed since percpu buffers are used
  49         local_irq_save(flags);
  50         if (write)
  51                 per_cpu(blockCnt, cpu)[BLOCK_RQ_WR] += size;
  52         else
  53                 per_cpu(blockCnt, cpu)[BLOCK_RQ_RD] += size;
  54         local_irq_restore(flags);
  55
  56         per_cpu(new_data_avail, cpu) = true;
  57 }
  58
  59 static int gator_events_block_create_files(struct super_block *sb, struct dentry *root)
  60 {
  61         struct dentry *dir;
  62
  63         /* block_complete_wr */
  64         dir = gatorfs_mkdir(sb, root, "Linux_block_rq_wr");
  65         if (!dir) {
  66                 return -1;
  67         }
  68         gatorfs_create_ulong(sb, dir, "enabled", &block_rq_wr_enabled);
  69         gatorfs_create_ro_ulong(sb, dir, "key", &block_rq_wr_key);
  70
  71         /* block_complete_rd */
  72         dir = gatorfs_mkdir(sb, root, "Linux_block_rq_rd");
  73         if (!dir) {
  74                 return -1;
  75         }
  76         gatorfs_create_ulong(sb, dir, "enabled", &block_rq_rd_enabled);
  77         gatorfs_create_ro_ulong(sb, dir, "key", &block_rq_rd_key);
  78
  79         return 0;
  80 }
  81
  82 static int gator_events_block_start(void)
  83 {
  84         int cpu;
  85
  86         for_each_present_cpu(cpu)
  87                 per_cpu(new_data_avail, cpu) = true;
  88
  89         // register tracepoints
  90         if (block_rq_wr_enabled || block_rq_rd_enabled)
  91                 if (GATOR_REGISTER_TRACE(block_rq_complete))
  92                         goto fail_block_rq_exit;
  93         pr_debug("gator: registered block event tracepoints\n");
  94
  95         return 0;
  96
  97         // unregister tracepoints on error
  98 fail_block_rq_exit:
  99         pr_err("gator: block event tracepoints failed to activate, please verify that tracepoints are enabled in the linux kernel\n");
 100
 101         return -1;
 102 }
 103
 104 static void gator_events_block_stop(void)
 105 {
 106         if (block_rq_wr_enabled || block_rq_rd_enabled)
 107                 GATOR_UNREGISTER_TRACE(block_rq_complete);
 108         pr_debug("gator: unregistered block event tracepoints\n");
 109
 110         block_rq_wr_enabled = 0;
 111         block_rq_rd_enabled = 0;
 112 }
 113
 114 static int gator_events_block_read(int **buffer)
 115 {
 116         unsigned long flags;
 117         int len, value, cpu, data = 0;
 118         cpu = smp_processor_id();
 119
 120         if (per_cpu(new_data_avail, cpu) == false)
 121                 return 0;
 122
 123         per_cpu(new_data_avail, cpu) = false;
 124
 125         len = 0;
 126         if (block_rq_wr_enabled) {
 127                 local_irq_save(flags);
 128                 value = per_cpu(blockCnt, cpu)[BLOCK_RQ_WR];
 129                 per_cpu(blockCnt, cpu)[BLOCK_RQ_WR] = 0;
 130                 local_irq_restore(flags);
 131                 per_cpu(blockGet, cpu)[len++] = block_rq_wr_key;
 132                 per_cpu(blockGet, cpu)[len++] = value;
 133                 data += value;
 134         }
 135         if (block_rq_rd_enabled) {
 136                 local_irq_save(flags);
 137                 value = per_cpu(blockCnt, cpu)[BLOCK_RQ_RD];
 138                 per_cpu(blockCnt, cpu)[BLOCK_RQ_RD] = 0;
 139                 local_irq_restore(flags);
 140                 per_cpu(blockGet, cpu)[len++] = block_rq_rd_key;
 141                 per_cpu(blockGet, cpu)[len++] = value;
 142                 data += value;
 143         }
 144
 145         if (data != 0)
 146                 per_cpu(new_data_avail, cpu) = true;
 147
 148         if (buffer)
 149                 *buffer = per_cpu(blockGet, cpu);
 150
 151         return len;
 152 }
 153
 154 static struct gator_interface gator_events_block_interface = {
 155         .create_files = gator_events_block_create_files,
 156         .start = gator_events_block_start,
 157         .stop = gator_events_block_stop,
 158         .read = gator_events_block_read,
 159 };
 160
 161 int gator_events_block_init(void)
 162 {
 163         block_rq_wr_enabled = 0;
 164         block_rq_rd_enabled = 0;
 165
 166         block_rq_wr_key = gator_events_get_key();
 167         block_rq_rd_key = gator_events_get_key();
 168
 169         return gator_events_install(&gator_events_block_interface);
 170 }
 171 gator_events_init(gator_events_block_init);