drivers/gator/gator_events_block.c

   1 /**
   2  * Copyright (C) ARM Limited 2010-2014. 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 atomic_t blockCnt[BLOCK_TOTAL];
  29 static int blockGet[BLOCK_TOTAL * 4];
  30
  31 /* Tracepoint changed in 3.15 backported to older kernels. The Makefile tries to autodetect the correct value, but if it fails change the #if below */
  32 #if OLD_BLOCK_RQ_COMPLETE
  33 GATOR_DEFINE_PROBE(block_rq_complete, TP_PROTO(struct request_queue *q, struct request *rq))
  34 #else
  35 GATOR_DEFINE_PROBE(block_rq_complete, TP_PROTO(struct request_queue *q, struct request *rq, unsigned int nr_bytes))
  36 #endif
  37 {
  38         int write;
  39         unsigned int size;
  40
  41         if (!rq)
  42                 return;
  43
  44         write = rq->cmd_flags & EVENTWRITE;
  45 #if OLD_BLOCK_RQ_COMPLETE
  46         size = rq->resid_len;
  47 #else
  48         size = nr_bytes;
  49 #endif
  50
  51         if (!size)
  52                 return;
  53
  54         if (write) {
  55                 if (block_rq_wr_enabled)
  56                         atomic_add(size, &blockCnt[BLOCK_RQ_WR]);
  57         } else {
  58                 if (block_rq_rd_enabled)
  59                         atomic_add(size, &blockCnt[BLOCK_RQ_RD]);
  60         }
  61 }
  62
  63 static int gator_events_block_create_files(struct super_block *sb, struct dentry *root)
  64 {
  65         struct dentry *dir;
  66
  67         /* block_complete_wr */
  68         dir = gatorfs_mkdir(sb, root, "Linux_block_rq_wr");
  69         if (!dir)
  70                 return -1;
  71         gatorfs_create_ulong(sb, dir, "enabled", &block_rq_wr_enabled);
  72         gatorfs_create_ro_ulong(sb, dir, "key", &block_rq_wr_key);
  73
  74         /* block_complete_rd */
  75         dir = gatorfs_mkdir(sb, root, "Linux_block_rq_rd");
  76         if (!dir)
  77                 return -1;
  78         gatorfs_create_ulong(sb, dir, "enabled", &block_rq_rd_enabled);
  79         gatorfs_create_ro_ulong(sb, dir, "key", &block_rq_rd_key);
  80
  81         return 0;
  82 }
  83
  84 static int gator_events_block_start(void)
  85 {
  86         /* register tracepoints */
  87         if (block_rq_wr_enabled || block_rq_rd_enabled)
  88                 if (GATOR_REGISTER_TRACE(block_rq_complete))
  89                         goto fail_block_rq_exit;
  90         pr_debug("gator: registered block event tracepoints\n");
  91
  92         return 0;
  93
  94         /* unregister tracepoints on error */
  95 fail_block_rq_exit:
  96         pr_err("gator: block event tracepoints failed to activate, please verify that tracepoints are enabled in the linux kernel\n");
  97
  98         return -1;
  99 }
 100
 101 static void gator_events_block_stop(void)
 102 {
 103         if (block_rq_wr_enabled || block_rq_rd_enabled)
 104                 GATOR_UNREGISTER_TRACE(block_rq_complete);
 105         pr_debug("gator: unregistered block event tracepoints\n");
 106
 107         block_rq_wr_enabled = 0;
 108         block_rq_rd_enabled = 0;
 109 }
 110
 111 static int gator_events_block_read(int **buffer, bool sched_switch)
 112 {
 113         int len, value, data = 0;
 114
 115         if (!on_primary_core())
 116                 return 0;
 117
 118         len = 0;
 119         if (block_rq_wr_enabled && (value = atomic_read(&blockCnt[BLOCK_RQ_WR])) > 0) {
 120                 atomic_sub(value, &blockCnt[BLOCK_RQ_WR]);
 121                 blockGet[len++] = block_rq_wr_key;
 122                 /* Indicates to Streamline that value bytes were written now, not since the last message */
 123                 blockGet[len++] = 0;
 124                 blockGet[len++] = block_rq_wr_key;
 125                 blockGet[len++] = value;
 126                 data += value;
 127         }
 128         if (block_rq_rd_enabled && (value = atomic_read(&blockCnt[BLOCK_RQ_RD])) > 0) {
 129                 atomic_sub(value, &blockCnt[BLOCK_RQ_RD]);
 130                 blockGet[len++] = block_rq_rd_key;
 131                 /* Indicates to Streamline that value bytes were read now, not since the last message */
 132                 blockGet[len++] = 0;
 133                 blockGet[len++] = block_rq_rd_key;
 134                 blockGet[len++] = value;
 135                 data += value;
 136         }
 137
 138         if (buffer)
 139                 *buffer = blockGet;
 140
 141         return len;
 142 }
 143
 144 static struct gator_interface gator_events_block_interface = {
 145         .create_files = gator_events_block_create_files,
 146         .start = gator_events_block_start,
 147         .stop = gator_events_block_stop,
 148         .read = gator_events_block_read,
 149 };
 150
 151 int gator_events_block_init(void)
 152 {
 153         block_rq_wr_enabled = 0;
 154         block_rq_rd_enabled = 0;
 155
 156         block_rq_wr_key = gator_events_get_key();
 157         block_rq_rd_key = gator_events_get_key();
 158
 159         return gator_events_install(&gator_events_block_interface);
 160 }