ceph/src/seastar/tests/unit/slab_test.cc

   1 /*
   2  * This file is open source software, licensed to you under the terms
   3  * of the Apache License, Version 2.0 (the "License").  See the NOTICE file
   4  * distributed with this work for additional information regarding copyright
   5  * ownership.  You may not use this file except in compliance with the License.
   6  *
   7  * You may obtain a copy of the License at
   8  *
   9  *   http://www.apache.org/licenses/LICENSE-2.0
  10  *
  11  * Unless required by applicable law or agreed to in writing,
  12  * software distributed under the License is distributed on an
  13  * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
  14  * KIND, either express or implied.  See the License for the
  15  * specific language governing permissions and limitations
  16  * under the License.
  17  */
  18 /*
  19  * Copyright (C) 2015 Cloudius Systems, Ltd.
  20  *
  21  * To compile: g++ -std=c++14 slab_test.cc
  22  */
  23
  24 #include <iostream>
  25 #include <assert.h>
  26 #include <seastar/core/slab.hh>
  27
  28 using namespace seastar;
  29
  30 namespace bi = boost::intrusive;
  31
  32 static constexpr size_t max_object_size = 1024*1024;
  33
  34 class item : public slab_item_base {
  35 public:
  36     bi::list_member_hook<> _cache_link;
  37     uint32_t _slab_page_index;
  38
  39     item(uint32_t slab_page_index) : _slab_page_index(slab_page_index) {}
  40
  41     const uint32_t get_slab_page_index() {
  42         return _slab_page_index;
  43     }
  44     const bool is_unlocked() {
  45         return true;
  46     }
  47 };
  48
  49 template<typename Item>
  50 static void free_vector(slab_allocator<Item>& slab, std::vector<item *>& items) {
  51     for (auto item : items) {
  52         slab.free(item);
  53     }
  54 }
  55
  56 static void test_allocation_1(const double growth_factor, const unsigned slab_limit_size) {
  57     slab_allocator<item> slab(growth_factor, slab_limit_size, max_object_size);
  58     size_t size = max_object_size;
  59
  60     slab.print_slab_classes();
  61
  62     std::vector<item *> items;
  63
  64     assert(slab_limit_size % size == 0);
  65     for (auto i = 0u; i < (slab_limit_size / size); i++) {
  66         auto item = slab.create(size);
  67         items.push_back(item);
  68     }
  69     assert(slab.create(size) == nullptr);
  70
  71     free_vector<item>(slab, items);
  72     std::cout << __FUNCTION__ << " done!\n";
  73 }
  74
  75 static void test_allocation_2(const double growth_factor, const unsigned slab_limit_size) {
  76     slab_allocator<item> slab(growth_factor, slab_limit_size, max_object_size);
  77     size_t size = 1024;
  78
  79     std::vector<item *> items;
  80
  81     auto allocations = 0u;
  82     for (;;) {
  83         auto item = slab.create(size);
  84         if (!item) {
  85             break;
  86         }
  87         items.push_back(item);
  88         allocations++;
  89     }
  90
  91     auto class_size = slab.class_size(size);
  92     auto per_slab_page = max_object_size / class_size;
  93     auto available_slab_pages = slab_limit_size / max_object_size;
  94     assert(allocations == (per_slab_page * available_slab_pages));
  95
  96     free_vector<item>(slab, items);
  97     std::cout << __FUNCTION__ << " done!\n";
  98 }
  99
 100 static void test_allocation_with_lru(const double growth_factor, const unsigned slab_limit_size) {
 101     bi::list<item, bi::member_hook<item, bi::list_member_hook<>, &item::_cache_link>> _cache;
 102     unsigned evictions = 0;
 103
 104     slab_allocator<item> slab(growth_factor, slab_limit_size, max_object_size,
 105         [&](item& item_ref) { _cache.erase(_cache.iterator_to(item_ref)); evictions++; });
 106     size_t size = max_object_size;
 107
 108     auto max = slab_limit_size / max_object_size;
 109     for (auto i = 0u; i < max * 1000; i++) {
 110         auto item = slab.create(size);
 111         assert(item != nullptr);
 112         _cache.push_front(*item);
 113     }
 114     assert(evictions == max * 999);
 115
 116     _cache.clear();
 117
 118     std::cout << __FUNCTION__ << " done!\n";
 119 }
 120
 121 int main(int ac, char** av) {
 122     test_allocation_1(1.25, 5*1024*1024);
 123     test_allocation_2(1.07, 5*1024*1024); // 1.07 is the growth factor used by facebook.
 124     test_allocation_with_lru(1.25, 5*1024*1024);
 125
 126     return 0;
 127 }