I installed ubuntu18 server and uploaded my own site ... How can I set the speed for every person who visits my site and download from it ???
Some packages in the Ubuntu repositories provide pre-compiled binaries of shared libraries (*.so
). For example, the package fftw2
provides the FFTW library (version 2), including the MPI-related library files /usr/lib/libfftw_mpi.so.2
and /usr/lib/librfftw_mpi.so.2
. This evokes the question of which of the numerous MPI libraries these files are actually linked against. On my system (amd64
), ldd /usr/lib/libfftw_mpi.so.2
shows
linux-vdso.so.1 (0x00007ffd80ba4000) libm.so.6 => /lib/x86_64-linux-gnu/libm.so.6 (0x00007f2c3fe22000) libmpi.so.20 => /usr/lib/x86_64-linux-gnu/libmpi.so.20 (0x00007f2c3fb30000) […]
So they seem to point to Open MPI, whose files are called libmpi.so
on Ubuntu.
I have found the mpi-default-dev
metapackage, whose description is
This metapackage depends on the development files of the recommended MPI implementation for each platform, currently Open MPI on all of the platforms where it exists, and MPICH on the others. The package which this depends on has alternatives links for the shared libraries libmpi and libmpi++, and for compilers mpicc, mpic++/mpicxx/mpiCC, mpif77 and mpi90 and their manpages.
And indeed, on amd64
, this pulls in Open MPI. However, does that mean that all libraries using MPI in the Ubuntu repositories are necessarily compiled with/linked against Open MPI?
I am trying to compile a large project, it includes a library:
SAMG/ifort64.9.1.041-emt64/lib/libguide.so
when I try to make project, there is an error message:
hidden symbol `pthread_atfork' in /usr/lib/x86_64-linux-gnu/libpthread_nonshared.a(pthread_atfork.oS) is referenced by DSO
/usr/bin/ld: final link failed: Bad value
I was trying add -pthreads as well as -lpthreads but it does not help.