PMPI和otf2：在CPP程序中链接C代码

• Z时代
• 2024-01-10
• 分类：问答

我有一个由wrap.py生成的CPP程序。 wrap.py用于为MPI程序生成包装。它将任何正常的MPI呼叫重定向到PMPI呼叫用于拦截目的，以便例如性能分析。请下载生成的代码here。我使用otf2来跟踪MPI程序。PMPI和otf2：在CPP程序中链接C代码

要解释代码：

// test4.cpp 
__attribute__((constructor)) void init(void) 
{ 
    if(!is_init) 
    { 
    archive = OTF2_Archive_Open("./", 
           "ArchiveTest", 
           OTF2_FILEMODE_WRITE, 
           1024 * 1024 /* event chunk size */, 
           4 * 1024 * 1024 /* def chunk size */, 
           OTF2_SUBSTRATE_POSIX, 
           OTF2_COMPRESSION_NONE); 
    is_init = true; 
    } 
} 
__attribute__((destructor)) void fini(void) 
{ 
    if(is_init) 
    { 
    OTF2_Archive_Close(archive); 
    is_init = false; 
    } 
} 

我要编译代码为.so文件。所以当它被导入时，constructor会被调用;当.so被分离时，destructor被调用。

据otf2 here官方文档，我编译程序：

mpic++ -fpic -c `otf2-config --cflags` -o test4.o test4.cpp 
mpic++ -shared -o libtest4.so `otf2-config --ldflags` `otf2-config --libs` test4.o 

如果要扩展上面的命令行，你会得到：

mpic++ -fpic -c -I/usr/include -o test4.o test4.cpp 
mpic++ -shared -o libtest4.so -L/usr/lib -lotf2 -lm test4.o 

被拦截的MPI程序是从here。

待办事项拦截：

$ mpirun -n 2 -x LD_PRELOAD=./libtest4.so ./send_recv 
./send_recv: symbol lookup error: ./libtest4.so: undefined symbol: OTF2_Archive_Open 
./send_recv: symbol lookup error: ./libtest4.so: undefined symbol: OTF2_Archive_Open 
------------------------------------------------------- 
Primary job terminated normally, but 1 process returned 
a non-zero exit code.. Per user-direction, the job has been aborted. 
------------------------------------------------------- 
-------------------------------------------------------------------------- 
mpirun detected that one or more processes exited with non-zero status, thus causing 
the job to be terminated. The first process to do so was: 
    Process name: [[20246,1],0] 
    Exit code: 127 
-------------------------------------------------------------------------- 

所以看起来混合C和CPP引起的问题。链接器无法正确生成符号为OTF2_Archive_Open和OTF2_Archive_Close的C函数。

我加2页的声明，告诉连接这些都是C函数（下载修改后的程序here）：

_EXTERN_C_ OTF2_Archive* OTF2_Archive_Open (const char * archivePath, 
const char * archiveName, 
const OTF2_FileMode fileMode, 
const uint64_t chunkSizeEvents, 
const uint64_t chunkSizeDefs, 
const OTF2_FileSubstrate fileSubstrate, 
const OTF2_Compression compression 
); 
_EXTERN_C_ OTF2_ErrorCode OTF2_Archive_Close (OTF2_Archive * archive); 

但上方停留的问题。和建议？

UPDATE1： OTF2提供.a文件，而不是.so文件。

$ nm /usr/lib/libotf2.a| grep -i OTF2_Archive_Open 
       U otf2_archive_open 
0000000000000000 T OTF2_Archive_Open 
       U otf2_archive_open_def_files 
00000000000032e0 T OTF2_Archive_OpenDefFiles 
       U otf2_archive_open_evt_files 
00000000000030e0 T OTF2_Archive_OpenEvtFiles 
       U otf2_archive_open_snap_files 
00000000000034e0 T OTF2_Archive_OpenSnapFiles 
       U OTF2_Archive_Open 
0000000000001180 T otf2_archive_open 
0000000000005a40 T otf2_archive_open_def_files 
       U OTF2_Archive_OpenDefFiles 
0000000000005880 T otf2_archive_open_evt_files 
       U OTF2_Archive_OpenEvtFiles 
0000000000005c00 T otf2_archive_open_snap_files 
       U OTF2_Archive_OpenSnapFiles 
$ ldd ./libtest4.so 
    linux-vdso.so.1 => (0x00007ffe3a6ce000) 
    libmpi_cxx.so.1 => /usr/lib/libmpi_cxx.so.1 (0x00007f4757d67000) 
    libmpi.so.12 => /usr/lib/libmpi.so.12 (0x00007f4757a91000) 
    libstdc++.so.6 => /usr/lib/x86_64-linux-gnu/libstdc++.so.6 (0x00007f475770e000) 
    libgcc_s.so.1 => /lib/x86_64-linux-gnu/libgcc_s.so.1 (0x00007f47574f8000) 
    libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f475712e000) 
    libibverbs.so.1 => /usr/lib/libibverbs.so.1 (0x00007f4756f1e000) 
    libopen-rte.so.12 => /usr/lib/libopen-rte.so.12 (0x00007f4756ca4000) 
    libopen-pal.so.13 => /usr/lib/libopen-pal.so.13 (0x00007f4756a07000) 
    libpthread.so.0 => /lib/x86_64-linux-gnu/libpthread.so.0 (0x00007f47567e9000) 
    libm.so.6 => /lib/x86_64-linux-gnu/libm.so.6 (0x00007f47564e0000) 
    /lib64/ld-linux-x86-64.so.2 (0x00005620bef03000) 
    libdl.so.2 => /lib/x86_64-linux-gnu/libdl.so.2 (0x00007f47562dc000) 
    libhwloc.so.5 => /usr/lib/x86_64-linux-gnu/libhwloc.so.5 (0x00007f47560a1000) 
    librt.so.1 => /lib/x86_64-linux-gnu/librt.so.1 (0x00007f4755e99000) 
    libutil.so.1 => /lib/x86_64-linux-gnu/libutil.so.1 (0x00007f4755c96000) 
    libnuma.so.1 => /usr/lib/x86_64-linux-gnu/libnuma.so.1 (0x00007f4755a8a000) 
    libltdl.so.7 => /usr/lib/x86_64-linux-gnu/libltdl.so.7 (0x00007f4755880000) 
$ nm ./libtest4.so | grep -i OTF2_Archive_Open 
       U OTF2_Archive_Open 

奇怪的是，我没有看到任何libotf2.a在ldd输出。但是，如果你从他们的网站上试用otf2 mpi writer的标准示例，它就可以实现。而otf2 mpi writer的标准示例ldd的输出也不包含libotf2.a。您可以找到示例here。

回答：

mpic++ -shared test4.o -o libtest4.so `otf2-config --ldflags` `otf2-config --libs` 

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