ceph/src/os/bluestore/Allocator.cc

   1 // -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
   2 // vim: ts=8 sw=2 smarttab
   3
   4 #include "Allocator.h"
   5 #include "StupidAllocator.h"
   6 #include "BitmapAllocator.h"
   7 #include "AvlAllocator.h"
   8 #include "HybridAllocator.h"
   9 #ifdef HAVE_LIBZBD
  10 #include "ZonedAllocator.h"
  11 #endif
  12 #include "common/debug.h"
  13 #include "common/admin_socket.h"
  14 #define dout_subsys ceph_subsys_bluestore
  15
  16 using std::string;
  17 using std::to_string;
  18
  19 using ceph::bufferlist;
  20 using ceph::Formatter;
  21
  22 class Allocator::SocketHook : public AdminSocketHook {
  23   Allocator *alloc;
  24
  25   friend class Allocator;
  26   std::string name;
  27 public:
  28   explicit SocketHook(Allocator *alloc,
  29                       const std::string& _name) :
  30     alloc(alloc), name(_name)
  31   {
  32     AdminSocket *admin_socket = g_ceph_context->get_admin_socket();
  33     if (name.empty()) {
  34       name = to_string((uintptr_t)this);
  35     }
  36     if (admin_socket) {
  37       int r = admin_socket->register_command(
  38         ("bluestore allocator dump " + name).c_str(),
  39         this,
  40         "dump allocator free regions");
  41       if (r != 0)
  42         alloc = nullptr; //some collision, disable
  43       if (alloc) {
  44         r = admin_socket->register_command(
  45           ("bluestore allocator score " + name).c_str(),
  46           this,
  47           "give score on allocator fragmentation (0-no fragmentation, 1-absolute fragmentation)");
  48         ceph_assert(r == 0);
  49         r = admin_socket->register_command(
  50           ("bluestore allocator fragmentation " + name).c_str(),
  51           this,
  52           "give allocator fragmentation (0-no fragmentation, 1-absolute fragmentation)");
  53         ceph_assert(r == 0);
  54       }
  55     }
  56   }
  57   ~SocketHook()
  58   {
  59     AdminSocket *admin_socket = g_ceph_context->get_admin_socket();
  60     if (admin_socket && alloc) {
  61       admin_socket->unregister_commands(this);
  62     }
  63   }
  64
  65   int call(std::string_view command,
  66            const cmdmap_t& cmdmap,
  67            Formatter *f,
  68            std::ostream& ss,
  69            bufferlist& out) override {
  70     int r = 0;
  71     if (command == "bluestore allocator dump " + name) {
  72       f->open_object_section("allocator_dump");
  73       f->dump_unsigned("capacity", alloc->get_capacity());
  74       f->dump_unsigned("alloc_unit", alloc->get_block_size());
  75       f->dump_string("alloc_type", alloc->get_type());
  76       f->dump_string("alloc_name", name);
  77
  78       f->open_array_section("extents");
  79       auto iterated_allocation = [&](size_t off, size_t len) {
  80         ceph_assert(len > 0);
  81         f->open_object_section("free");
  82         char off_hex[30];
  83         char len_hex[30];
  84         snprintf(off_hex, sizeof(off_hex) - 1, "0x%lx", off);
  85         snprintf(len_hex, sizeof(len_hex) - 1, "0x%lx", len);
  86         f->dump_string("offset", off_hex);
  87         f->dump_string("length", len_hex);
  88         f->close_section();
  89       };
  90       alloc->dump(iterated_allocation);
  91       f->close_section();
  92       f->close_section();
  93     } else if (command == "bluestore allocator score " + name) {
  94       f->open_object_section("fragmentation_score");
  95       f->dump_float("fragmentation_rating", alloc->get_fragmentation_score());
  96       f->close_section();
  97     } else if (command == "bluestore allocator fragmentation " + name) {
  98       f->open_object_section("fragmentation");
  99       f->dump_float("fragmentation_rating", alloc->get_fragmentation());
 100       f->close_section();
 101     } else {
 102       ss << "Invalid command" << std::endl;
 103       r = -ENOSYS;
 104     }
 105     return r;
 106   }
 107
 108 };
 109 Allocator::Allocator(const std::string& name,
 110                      int64_t _capacity,
 111                      int64_t _block_size)
 112   : capacity(_capacity), block_size(_block_size)
 113 {
 114   asok_hook = new SocketHook(this, name);
 115 }
 116
 117
 118 Allocator::~Allocator()
 119 {
 120   delete asok_hook;
 121 }
 122
 123 const string& Allocator::get_name() const {
 124   return asok_hook->name;
 125 }
 126
 127 Allocator *Allocator::create(CephContext* cct, string type,
 128                              int64_t size, int64_t block_size, const std::string& name)
 129 {
 130   Allocator* alloc = nullptr;
 131   if (type == "stupid") {
 132     alloc = new StupidAllocator(cct, name, size, block_size);
 133   } else if (type == "bitmap") {
 134     alloc = new BitmapAllocator(cct, size, block_size, name);
 135   } else if (type == "avl") {
 136     return new AvlAllocator(cct, size, block_size, name);
 137   } else if (type == "hybrid") {
 138     return new HybridAllocator(cct, size, block_size,
 139       cct->_conf.get_val<uint64_t>("bluestore_hybrid_alloc_mem_cap"),
 140       name);
 141 #ifdef HAVE_LIBZBD
 142   } else if (type == "zoned") {
 143     return new ZonedAllocator(cct, size, block_size, name);
 144 #endif
 145   }
 146   if (alloc == nullptr) {
 147     lderr(cct) << "Allocator::" << __func__ << " unknown alloc type "
 148              << type << dendl;
 149   }
 150   return alloc;
 151 }
 152
 153 void Allocator::release(const PExtentVector& release_vec)
 154 {
 155   interval_set<uint64_t> release_set;
 156   for (auto e : release_vec) {
 157     release_set.insert(e.offset, e.length);
 158   }
 159   release(release_set);
 160 }
 161
 162 /**
 163  * Gives fragmentation a numeric value.
 164  *
 165  * Following algorithm applies value to each existing free unallocated block.
 166  * Value of single block is a multiply of size and per-byte-value.
 167  * Per-byte-value is greater for larger blocks.
 168  * Assume block size X has value per-byte p; then block size 2*X will have per-byte value 1.1*p.
 169  *
 170  * This could be expressed in logarithms, but for speed this is interpolated inside ranges.
 171  * [1]  [2..3] [4..7] [8..15] ...
 172  * ^    ^      ^      ^
 173  * 1.1  1.1^2  1.1^3  1.1^4 ...
 174  *
 175  * Final score is obtained by proportion between score that would have been obtained
 176  * in condition of absolute fragmentation and score in no fragmentation at all.
 177  */
 178 double Allocator::get_fragmentation_score()
 179 {
 180   // this value represents how much worth is 2X bytes in one chunk then in X + X bytes
 181   static const double double_size_worth = 1.1 ;
 182   std::vector<double> scales{1};
 183   double score_sum = 0;
 184   size_t sum = 0;
 185
 186   auto get_score = [&](size_t v) -> double {
 187     size_t sc = sizeof(v) * 8 - clz(v) - 1; //assign to grade depending on log2(len)
 188     while (scales.size() <= sc + 1) {
 189       //unlikely expand scales vector
 190       scales.push_back(scales[scales.size() - 1] * double_size_worth);
 191     }
 192
 193     size_t sc_shifted = size_t(1) << sc;
 194     double x = double(v - sc_shifted) / sc_shifted; //x is <0,1) in its scale grade
 195     // linear extrapolation in its scale grade
 196     double score = (sc_shifted    ) * scales[sc]   * (1-x) +
 197                    (sc_shifted * 2) * scales[sc+1] * x;
 198     return score;
 199   };
 200
 201   auto iterated_allocation = [&](size_t off, size_t len) {
 202     ceph_assert(len > 0);
 203     score_sum += get_score(len);
 204     sum += len;
 205   };
 206   dump(iterated_allocation);
 207
 208
 209   double ideal = get_score(sum);
 210   double terrible = sum * get_score(1);
 211   return (ideal - score_sum) / (ideal - terrible);
 212 }