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#include <iostream>

uint64_t get_mem_use(const char* msg)

{

ifstream ifs;

ifs.open("/proc/self/status");

const char* mem_use_keyword="VmRSS:";

uint64_t mem_use = 0;

while(!ifs.eof()){

char s[256];

ifs.getline(s, sizeof(s));

char* name = strstr(s, mem_use_keyword);

if ( name != nullptr) {

cout << msg << s << std::endl;

name += strlen(mem_use_keyword);

mem_use = strtol(name, nullptr, 10);

mem_use <<= 10; // * 1024

}

}

ifs.close();

return mem_use;

}

TEST(mempool, align_overhead)

{

vector <bufferlist*> allocs;

size_t bsize = 0x1000;

size_t alloc_count = 0x400000; // allocate 16 Gb total

allocs.resize(alloc_count);

uint64_t mem_use_before = get_mem_use("Mem before: ");

for( auto i = 0u; i < alloc_count; ++i) {

bufferptr p = buffer::create_page_aligned(bsize);

bufferlist* bl = new bufferlist;

bl->append(p);

*(bl->c_str()) = 0; // touch the page to increment system mem use

allocs[i] = bl;

}

uint64_t mem_use_after = get_mem_use("Mem after: ");

uint64_t used = mem_use_after - mem_use_before;

uint64_t bytes = mempool::buffer_data::allocated_bytes();

cout << "Mem actually used: " << used << " bytes" << std::endl;

cout << "Mem pool reports: " << bytes << " bytes" << std::endl;

for( auto i = 0u; i < alloc_count; ++i) {

delete allocs[i];

}

allocs.clear();

mem_use_before = get_mem_use("Mem before2: ");

struct fake_raw_posix_aligned{

char stub[8];

void* data;

fake_raw_posix_aligned() {

::posix_memalign(&data, 0x1000, 0x1000); //mempool::buffer_data::alloc_char.allocate_aligned(0x1000, 0x1000);

*((char*)data) = 0; // touch the page

}

~fake_raw_posix_aligned() {

::free(data);

}

};

vector <fake_raw_posix_aligned*> allocs2;

allocs2.resize(alloc_count);

for( auto i = 0u; i < alloc_count; ++i) {

allocs2[i] = new fake_raw_posix_aligned();

}

mem_use_after = get_mem_use("Mem after2: ");

used = mem_use_after - mem_use_before;

// uint64_t bytes = mempool::buffer_data::allocated_bytes();

cout << "Mem actually used: " << used << " bytes" << std::endl;

// cout << "Mem pool reports: " << bytes << " bytes" << std::endl;

for( auto i = 0u; i < alloc_count; ++i) {

delete allocs2[i];

}

allocs2.clear();

}