in xenial, we are using the toolchain test build ppa[0] for GCC-7.3. but unlike the hevaily pached GCC offered by SCLs in centos/rhel 7, the GCC on ubuntu xenial does not link against libstdc++ by default. we need to use -static-libstdc++ and -static-libgcc to avoid the runtime dependency on libstdc++ and libgcc of ceph when it runs on xenial without the ppa repo for building it. it's a viable solution. but we need to be careful. as all shared libraries we are linking against should not rely on libstdc++ if we go with it. namely, the C++ libraries we are using are: librocksdb, libsnappy, libtcmalloc. * rocksdb is included by our dist tarball, and can be optionally built by ourself. so it's fine. * snappy's case is a little bit complicated. we use it in two ways: - we have a snappy compressor plugin. so we can link the snappy plugin against it statically. - rocksdb can optionally use snappy as a inline compress algorithm. but currently rocksdb's building system does not offer a way to link against libsnappy.a. so at this moment, we can simply disable rocksdb's snappy support. and probably, we can address it on the rocksdb side later on. * tcmalloc is a allocator library offered by gperf-tools, which is also a C++ library. and libtcmalloc.a is available in xenial's libgoogle-perftools-dev package. but it not is compiled with -fPIC option. so we will run into following error: /usr/bin/ld: /usr/lib/libtcmalloc.a(libtcmalloc_la-tcmalloc.o): relocation R_X86_64_32 against `.rodata.str1.8' can not be used when making a shared object; recompile with -fPIC /usr/lib/libtcmalloc.a: error adding symbols: Bad value collect2: error: ld returned 1 exit status src/CMakeFiles/ceph-common.dir/build.make:434: recipe for target 'lib/libceph-common.so.0' failed recompiling libtcmalloc with -fPIC addresses this issue. but to recompile it, we need to include gperft-tools' source in our dist tarball. we also compile without tcmalloc, but on xenial, tcmalloc offers better performance than the ptmalloc does in multi-threaded environment, see [1]. i think that's why we introduced make tcmalloc the default, and also offer no-tcmalloc build of ceph. so i think, the safest option is to include gperftool as a submodule and our dist tarball. thoughts? -- [0] https://launchpad.net/~ubuntu-toolchain-r/+archive/ubuntu/test [1] https://gperftools.github.io/gperftools/tcmalloc.html -- Regards Kefu Chai -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
