ceph/src/common/perf_histogram.cc

   1 // -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
   2 // vim: ts=8 sw=2 smarttab
   3 /*
   4  * Ceph - scalable distributed file system
   5  *
   6  * Copyright (C) 2017 OVH
   7  *
   8  * This is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU Lesser General Public
  10  * License version 2.1, as published by the Free Software
  11  * Foundation.  See file COPYING.
  12  *
  13  */
  14
  15 #include "common/perf_histogram.h"
  16
  17 #include <limits>
  18
  19 void PerfHistogramCommon::dump_formatted_axis(
  20     ceph::Formatter *f, const PerfHistogramCommon::axis_config_d &ac) {
  21   f->open_object_section("axis");
  22
  23   // Dump axis configuration
  24   f->dump_string("name", ac.m_name);
  25   f->dump_int("min", ac.m_min);
  26   f->dump_int("quant_size", ac.m_quant_size);
  27   f->dump_int("buckets", ac.m_buckets);
  28   switch (ac.m_scale_type) {
  29     case SCALE_LINEAR:
  30       f->dump_string("scale_type", "linear");
  31       break;
  32     case SCALE_LOG2:
  33       f->dump_string("scale_type", "log2");
  34       break;
  35     default:
  36       assert(false && "Invalid scale type");
  37   }
  38
  39   {
  40     // Dump concrete ranges for axis buckets
  41     f->open_array_section("ranges");
  42     auto ranges = get_axis_bucket_ranges(ac);
  43     for (int i = 0; i < ac.m_buckets; ++i) {
  44       f->open_object_section("bucket");
  45       if (i > 0) {
  46         f->dump_int("min", ranges[i].first);
  47       }
  48       if (i < ac.m_buckets - 1) {
  49         f->dump_int("max", ranges[i].second);
  50       }
  51       f->close_section();
  52     }
  53     f->close_section();
  54   }
  55
  56   f->close_section();
  57 }
  58
  59 int64_t get_quants(int64_t i, PerfHistogramCommon::scale_type_d st) {
  60   switch (st) {
  61     case PerfHistogramCommon::SCALE_LINEAR:
  62       return i;
  63     case PerfHistogramCommon::SCALE_LOG2:
  64       return int64_t(1) << (i - 1);
  65   }
  66   assert(false && "Invalid scale type");
  67 }
  68
  69 int64_t PerfHistogramCommon::get_bucket_for_axis(
  70     int64_t value, const PerfHistogramCommon::axis_config_d &ac) {
  71   if (value < ac.m_min) {
  72     return 0;
  73   }
  74
  75   value -= ac.m_min;
  76   value /= ac.m_quant_size;
  77
  78   switch (ac.m_scale_type) {
  79     case SCALE_LINEAR:
  80       return std::min<int64_t>(value + 1, ac.m_buckets - 1);
  81
  82     case SCALE_LOG2:
  83       for (int64_t i = 1; i < ac.m_buckets; ++i) {
  84         if (value < get_quants(i, SCALE_LOG2)) {
  85           return i;
  86         }
  87       }
  88       return ac.m_buckets - 1;
  89   }
  90   assert(false && "Invalid scale type");
  91 }
  92
  93 std::vector<std::pair<int64_t, int64_t>>
  94 PerfHistogramCommon::get_axis_bucket_ranges(
  95     const PerfHistogramCommon::axis_config_d &ac) {
  96   std::vector<std::pair<int64_t, int64_t>> ret;
  97   ret.resize(ac.m_buckets);
  98
  99   // First bucket is for value < min
 100   int64_t min = ac.m_min;
 101   for (int64_t i = 1; i < ac.m_buckets - 1; i++) {
 102     int64_t max_exclusive =
 103         ac.m_min + get_quants(i, ac.m_scale_type) * ac.m_quant_size;
 104
 105     // Dump bucket range
 106     ret[i].first = min;
 107     ret[i].second = max_exclusive - 1;
 108
 109     // Shift min to next bucket
 110     min = max_exclusive;
 111   }
 112
 113   // Fill up first and last element, note that in case m_buckets == 1
 114   // those will point to the same element, the order is important here
 115   ret.front().second = ac.m_min - 1;
 116   ret.back().first = min;
 117
 118   ret.front().first = std::numeric_limits<int64_t>::min();
 119   ret.back().second = std::numeric_limits<int64_t>::max();
 120   return ret;
 121 }