Hi Jeff Squyres,
Thank you for your reply...
My problem is i want to *reduce library* size by removing unwanted plugin's.
Here *libmpi.so.12.0.3 *size is 2.4MB.
How can i know what are the* pluggin's *included to* build the*
*libmpi.so.12.0.3* and how can remove.
Thanks&Regards,
Mahesh N
On Fri, Oct 28, 2016 at 7:09 PM, Jeff Squyres (jsquyres) <jsquy...@cisco.com
> wrote:
> On Oct 28, 2016, at 8:12 AM, Mahesh Nanavalla <
> mahesh.nanavalla...@gmail.com> wrote:
> >
> > i have configured as below for arm
> >
> > ./configure --enable-orterun-prefix-by-default
> > --prefix="/home/nmahesh/Workspace/ARM_MPI/openmpi"
> CC=arm-openwrt-linux-muslgnueabi-gcc CXX=arm-openwrt-linux-muslgnueabi-g++
> --host=arm-openwrt-linux-muslgnueabi --enable-script-wrapper-compilers
> --disable-mpi-fortran --enable-dlopen --enable-shared --disable-vt
> --disable-java --disable-libompitrace --disable-static
>
> Note that there is a tradeoff here: --enable-dlopen will reduce the size
> of libmpi.so by splitting out all the plugins into separate DSOs (dynamic
> shared objects -- i.e., individual .so plugin files). But note that some
> of plugins are quite small in terms of code. I mention this because when
> you dlopen a DSO, it will load in DSOs in units of pages. So even if a DSO
> only has 1KB of code, it will use <page_size> of bytes in your running
> process (e.g., 4KB -- or whatever the page size is on your system).
>
> On the other hand, if you --disable-dlopen, then all of Open MPI's plugins
> are slurped into libmpi.so (and friends). Meaning: no DSOs, no dlopen, no
> page-boundary-loading behavior. This allows the compiler/linker to pack in
> all the plugins into memory more efficiently (because they'll be compiled
> as part of libmpi.so, and all the code is packed in there -- just like any
> other library). Your total memory usage in the process may be smaller.
>
> Sidenote: if you run more than one MPI process per node, then libmpi.so
> (and friends) will be shared between processes. You're assumedly running
> in an embedded environment, so I don't know if this factor matters (i.e., I
> don't know if you'll run with ppn>1), but I thought I'd mention it anyway.
>
> On the other hand (that's your third hand, for those at home counting...),
> you may not want to include *all* the plugins. I.e., there may be a bunch
> of plugins that you're not actually using, and therefore if they are
> compiled in as part of libmpi.so (and friends), they're consuming space
> that you don't want/need. So the dlopen mechanism might actually be better
> -- because Open MPI may dlopen a plugin at run time, determine that it
> won't be used, and then dlclose it (i.e., release the memory that would
> have been used for it).
>
> On the other (fourth!) hand, you can actually tell Open MPI to *not* build
> specific plugins with the --enable-dso-no-build=LIST configure option.
> I.e., if you know exactly what plugins you want to use, you can negate the
> ones that you *don't* want to use on the configure line, use
> --disable-static and --disable-dlopen, and you'll likely use the least
> amount of memory. This is admittedly a bit clunky, but Open MPI's
> configure process was (obviously) not optimized for this use case -- it's
> much more optimized to the "build everything possible, and figure out which
> to use at run time" use case.
>
> If you really want to hit rock bottom on MPI process size in your embedded
> environment, you can do some experimentation to figure out exactly which
> components you need. You can use repeated runs with "mpirun --mca
> ABC_base_verbose 100 ...", where "ABC" is each of Open MPI's framework
> names ("framework" = collection of plugins of the same type). This verbose
> output will show you exactly which components are opened, which ones are
> used, and which ones are discarded. You can build up a list of all the
> discarded components and --enable-mca-no-build them.
>
> > While i am running the using mpirun
> > am getting following errror..
> > root@OpenWrt:~# /usr/bin/mpirun --allow-run-as-root -np 1
> /usr/bin/openmpiWiFiBulb
> > ------------------------------------------------------------
> --------------
> > Sorry! You were supposed to get help about:
> > opal_init:startup:internal-failure
> > But I couldn't open the help file:
> >
> > /home/nmahesh/Workspace/ARM_MPI/openmpi/share/openmpi/help-opal-runtime.txt:
> No such file or directory. Sorry!
>
> So this is really two errors:
>
> 1. The help message file is not being found.
> 2. Something is obviously going wrong during opal_init() (which is one of
> Open MPI's startup functions).
>
> For #1, when I do a default build of Open MPI 1.10.3, that file *is*
> installed. Are you trimming the installation tree, perchance? If so, if
> you can put at least that one file back in its installation location (it's
> in the Open MPI source tarball), it might reveal more information on
> exactly what is failing.
>
> Additionally, I wonder if shared memory is not getting setup right. Try
> running with "mpirun --mca shmem_base_verbose 100 ..." and see if it's
> reporting an error.
>
> --
> Jeff Squyres
> jsquy...@cisco.com
> For corporate legal information go to: http://www.cisco.com/web/
> about/doing_business/legal/cri/
>
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