Memory leaks

Memory traces

VPP supports memory traces to help debug (suspected) memory leaks. Each allocation/deallocation is instrumented so that the number of allocations and current global allocated size is maintained for each unique allocation stack trace.

Looking at a memory trace can help diagnose where memory is (over-)used, and comparing memory traces at different point in time can help diagnose if and where memory leaks happen.

To enable memory traces on main-heap:

$ vppctl memory-trace on main-heap

To dump memory traces for analysis:

$ vppctl show memory main-heap verbose
Thread 0 vpp_main
  base 0x7fffb6422000, size 1g, locked, unmap-on-destroy, name 'main heap'
    page stats: page-size 4K, total 262144, mapped 30343, not-mapped 231801
      numa 0: 30343 pages, 118.53m bytes
    total: 1023.99M, used: 115.49M, free: 908.50M, trimmable: 908.48M
      free chunks 451 free fastbin blks 0
      max total allocated 1023.99M

  Bytes    Count     Sample   Traceback
 31457440        1 0x7fffbb31ad00 clib_mem_alloc_aligned_at_offset + 0x80
                                  clib_mem_alloc_aligned + 0x26
                                  alloc_aligned_8_8 + 0xe1
                                  clib_bihash_instantiate_8_8 + 0x76
                                  clib_bihash_init2_8_8 + 0x2ec
                                  clib_bihash_init_8_8 + 0x6a
                                  l2fib_table_init + 0x54
                                  set_int_l2_mode + 0x89
                                  int_l3 + 0xb4
                                  vlib_cli_dispatch_sub_commands + 0xeee
                                  vlib_cli_dispatch_sub_commands + 0xc62
                                  vlib_cli_dispatch_sub_commands + 0xc62
   266768     5222 0x7fffbd79f978 clib_mem_alloc_aligned_at_offset + 0x80
                                  vec_resize_allocate_memory + 0xa8
                                  _vec_resize_inline + 0x240
                                  unix_cli_file_add + 0x83d
                                  unix_cli_listen_read_ready + 0x10b
                                  linux_epoll_input_inline + 0x943
                                  linux_epoll_input + 0x39
                                  dispatch_node + 0x336
                                  vlib_main_or_worker_loop + 0xbf1
                                  vlib_main_loop + 0x1a
                                  vlib_main + 0xae7
                                  thread0 + 0x3e
....

libc memory traces

Internal VPP memory allocations rely on VPP main-heap, however when using external libraries, esp. in plugins (e.g. OpenSSL library used by the IKEv2 plugin), those external libraries usually manages memory using the standard libc malloc()/free()/… calls. This, in turn, makes use of the default libc heap.

VPP has no knowledge of this heap and tools such as memory traces cannot be used.

In order to enable the use of standard VPP debugging tools, this library replaces standard libc memory management calls with version using VPP main-heap.

To use it, you need to use the LD_PRELOAD mechanism, e.g.

~# LD_PRELOAD=/usr/lib/x86_64-linux-gnu/libvppmem_preload.so /usr/bin/vpp -c /etc/vpp/startup.conf

You can then use tools such as memory traces as usual.