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diff --git a/docs/troubleshooting/mem.rst b/docs/troubleshooting/mem.rst new file mode 100644 index 00000000000..5475051c085 --- /dev/null +++ b/docs/troubleshooting/mem.rst @@ -0,0 +1,84 @@ +.. _memleak: + +***************** +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: + +.. code-block:: console + $ vppctl memory-trace on main-heap + +To dump memory traces for analysis: + +.. code-block:: console + $ vppctl show memory-trace on main-heap + 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 (eg. 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, eg. + +.. code-block:: console + ~# 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. |