Question

我理解它的方式，存在许多不同的malloc实现：

dlmalloc - 通用分配器
ptmalloc2 - glibc
jemalloc - FreeBSD和Firefox
tcmalloc - Google
libumem - Solaris

有没有办法确定我的（linux）系统上实际使用了哪个malloc？

我读到“由于ptmalloc2的线程支持，它成为了linux的默认内存分配器。”我有什么方法可以自己检查一下吗？

我在问，因为我似乎没有通过在下面的代码中对malloc循环进行并列化来提高速度：

for (int i = 1; i <= 16; i += 1 ) {
    parallelMalloc(i);
}

 void parallelMalloc(int parallelism, int mallocCnt = 10000000) {

    omp_set_num_threads(parallelism);

    std::vector<char*> ptrStore(mallocCnt);

    boost::posix_time::ptime t1 = boost::posix_time::microsec_clock::local_time();

    #pragma omp parallel for
    for (int i = 0; i < mallocCnt; i++) {
        ptrStore[i] = ((char*)malloc(100 * sizeof(char)));
    }

    boost::posix_time::ptime t2 = boost::posix_time::microsec_clock::local_time();

    #pragma omp parallel for
    for (int i = 0; i < mallocCnt; i++) {
        free(ptrStore[i]);
    }

    boost::posix_time::ptime t3 = boost::posix_time::microsec_clock::local_time();


    boost::posix_time::time_duration malloc_time = t2 - t1;
    boost::posix_time::time_duration free_time   = t3 - t2;

    std::cout << " parallelism = "  << parallelism << "\t itr = " << mallocCnt <<  "\t malloc_time = " <<
            malloc_time.total_milliseconds() << "\t free_time = " << free_time.total_milliseconds() << std::endl;
}

给出了

的输出

 parallelism = 1         itr = 10000000  malloc_time = 1225      free_time = 1517
 parallelism = 2         itr = 10000000  malloc_time = 1614      free_time = 1112
 parallelism = 3         itr = 10000000  malloc_time = 1619      free_time = 687
 parallelism = 4         itr = 10000000  malloc_time = 2325      free_time = 620
 parallelism = 5         itr = 10000000  malloc_time = 2233      free_time = 550
 parallelism = 6         itr = 10000000  malloc_time = 2207      free_time = 489
 parallelism = 7         itr = 10000000  malloc_time = 2778      free_time = 398
 parallelism = 8         itr = 10000000  malloc_time = 1813      free_time = 389
 parallelism = 9         itr = 10000000  malloc_time = 1997      free_time = 350
 parallelism = 10        itr = 10000000  malloc_time = 1922      free_time = 291
 parallelism = 11        itr = 10000000  malloc_time = 2480      free_time = 257
 parallelism = 12        itr = 10000000  malloc_time = 1614      free_time = 256
 parallelism = 13        itr = 10000000  malloc_time = 1387      free_time = 289
 parallelism = 14        itr = 10000000  malloc_time = 1481      free_time = 248
 parallelism = 15        itr = 10000000  malloc_time = 1252      free_time = 297
 parallelism = 16        itr = 10000000  malloc_time = 1063      free_time = 281

如何知道使用哪个malloc？

0 个答案: