Re: [OMPI devel] RFC: rewrite of ORTE OOB

[Ralph Castain]

I have placed a tarball of this branch for those willing to MTT it:

http://www.open-mpi.org/~rhc/openmpi-1.9.tar.bz2

I will update if/when major changes are made.


On May 13, 2013, at 9:00 PM, Ralph Castain  wrote:

> Hi folks
> 
> As most of you know, I have been working for quite some time on rewriting the 
> OOB. It is now getting close to being ready to be committed.
> 
> Unfortunately, I am changing jobs on May 20th (starting a position at Intel) 
> that will cause a hopefully short "service interruption" in my ability to 
> contribute code to OMPI. I have started the legal paperwork to resolve that 
> situation and have the backing of my new management, but these things always 
> take time.
> 
> Ordinarily, I would simply hold off the commit until the paperwork was 
> completed. However, after talking with a few people in the community, the 
> changes are important and desirable enough to get this into the trunk without 
> the indefinite delay. I can continue to help debug even after my status 
> changes - just cannot directly contribute code. So I have committed the code 
> to the OMPI repository in a public temporary branch. Once the community 
> believes the code is ready, Jeff can merge it back to the trunk if I'm not 
> able to do so.
> 
> 
> WHAT:Rewrite of ORTE OOB
> 
> WHY:   Support asynchronous progress and a host of other features
> 
> WHEN:TBD (will discuss at weekly telecon and/or on mailing list)
> 
> SYNOPSIS:
> The current OOB has served us well, but a number of limitations have been 
> identified over the years. Specifically:
> 
> * it is only progressed when called via opal_progress, which can lead to 
> hangs or recursive calls into libevent (which is not supported by that code)
> 
> * we've had issues when multiple NICs are available as the code doesn't 
> "shift" messages between transports - thus, all nodes had to be available via 
> the same TCP interface.
> 
> * the OOB "unloads" incoming opal_buffer_t objects during the transmission, 
> thus preventing use of OBJ_RETAIN in the code when repeatedly sending the 
> same message to multiple recipients
> 
> * there is no failover mechanism across NICs - if the selected NIC (or its 
> attached switch) fails, we are forced to abort
> 
> * only one transport (i.e., component) can be "active"
> 
> 
> The revised OOB resolves these problems:
> 
> * async progress is used for all application processes, with the progress 
> thread blocking in the event library
> 
> * each available NIC is supported by its own TCP module. The ability to 
> asynchronously progress each module independently is provided, but not 
> enabled by default (a runtime MCA parameter turns it "on")
> 
> * multi-address NICs (e.g., a NIC with both an IPv4 and IPv6 address, or with 
> virtual interfaces) are supported - reachability is determined by comparing 
> the contact info for a peer against all addresses within the range covered by 
> the address/mask pairs for the NIC.
> 
> * a message that arrives on one NIC is automatically shifted to whatever NIC 
> that is connected to the next "hop" if that peer cannot be reached by the 
> incoming NIC. If no TCP module will reach the peer, then the OOB attempts to 
> send the message via all other available components - if none can reach the 
> peer, then an "error" is reported back to the RML, which then calls the 
> errmgr for instructions.
> 
> * opal_buffer_t now conforms to standard object rules re OBJ_RETAIN as we no 
> longer "unload" the incoming object
> 
> * NIC failure is reported to the TCP component, which then tries to resend 
> the message across any other available TCP NIC. If that doesn't work, then 
> the message is given back to the OOB base to try using other components. If 
> all that fails, then the error is reported to the RML, which reports to the 
> errmgr for instructions
> 
> * obviously from the above, multiple OOB components (e.g., TCP and UD) can be 
> active in parallel
> 
> * the matching code has been moved to the RML (and out of the OOB/TCP 
> component) so it is independent of transport
> 
> * routing is done by the individual OOB modules (as opposed to the RML). 
> Thus, both routed and non-routed transports can simultaneously be active
> 
> * all blocking send/recv APIs have been removed. Everything operates 
> asynchronously.
> 
> 
> KNOWN LIMITATIONS:
> 
> * although provision is made for component failover as described above, the 
> code for doing so has not been implemented yet. At the moment, if all 
> connections for a given component fail, the errmgr is notified of a "lost 
> connection", which by default results in termination of the job if it was a 
> lifeline
> 
> * the IPv6 code is present and compiles, but has not been tested as I don't 
> have access to any IPv6-enabled cluster
> 
> * routing is performed at the individual module level, yet the active routed 
> component is selected on a global basis. We probably should update that to 
> 

[hwloc-devel] Create success (hwloc r1.7.1rc1r5616)

[MPI Team]

Creating nightly hwloc snapshot SVN tarball was a success.

Snapshot:   hwloc 1.7.1rc1r5616
Start time: Tue May 14 21:05:20 EDT 2013
End time:   Tue May 14 21:09:17 EDT 2013

Your friendly daemon,
Cyrador

[hwloc-devel] Create success (hwloc r1.8a1r5615)

[MPI Team]

Creating nightly hwloc snapshot SVN tarball was a success.

Snapshot:   hwloc 1.8a1r5615
Start time: Tue May 14 21:01:01 EDT 2013
End time:   Tue May 14 21:05:19 EDT 2013

Your friendly daemon,
Cyrador

Re: [OMPI devel] Build warnings in trunk

[Ralph Castain]

I can take a gander at these

On May 14, 2013, at 2:30 PM, Rolf vandeVaart  wrote:

> CC base/oob_base_init.lo
> ../../../../orte/mca/oob/base/oob_base_init.c: In function 
> 'mca_oob_base_init':
> ../../../../orte/mca/oob/base/oob_base_init.c:55:43: warning: 's_component' 
> may be used uninitialized in this function
> 
>  CC ras_slurm_module.lo
> ../../../../../orte/mca/ras/slurm/ras_slurm_module.c: In function 'init':
> ../../../../../orte/mca/ras/slurm/ras_slurm_module.c:143:11: warning: 
> 'slurm_host' may be used uninitialized in this function
> ../../../../../orte/mca/ras/slurm/ras_slurm_module.c:144:14: warning: 'port' 
> may be used uninitialized in this function
> ../../../../../orte/mca/ras/slurm/ras_slurm_module.c: In function 'recv_data':
> ../../../../../orte/mca/ras/slurm/ras_slurm_module.c:742:31: warning: 'jtrk' 
> may be used uninitialized in this function
> ../../../../../orte/mca/ras/slurm/ras_slurm_module.c:740:17: warning: 'idx' 
> may be used uninitialized in this function
> ../../../../../orte/mca/ras/slurm/ras_slurm_module.c:740:22: warning: 'sjob' 
> may be used uninitialized in this function
> ../../../../../orte/mca/ras/slurm/ras_slurm_module.c:741:20: warning: 
> 'nodelist' may be used uninitialized in this function

Re: [OMPI devel] Build warnings in trunk

[Nathan Hjelm]

On Tue, May 14, 2013 at 02:30:17PM -0700, Rolf vandeVaart wrote:
> I have noticed several warnings while building the trunk.   Feel free to fix 
> anything that you are familiar with.  
> 
>   CC mca_base_param.lo
> ../../../../opal/mca/base/mca_base_param.c: In function 'register_param':
> ../../../../opal/mca/base/mca_base_param.c:113:25: warning: 'var_type' may be 
> used uninitialized in this function

I will take this one. I will put out the RFC for removing this code now.

-Nathan
HPC-3, LANL

[OMPI devel] Build warnings in trunk

[Rolf vandeVaart]

I have noticed several warnings while building the trunk.   Feel free to fix 
anything that you are familiar with.  

CC sys_limits.lo
../../../opal/util/sys_limits.c: In function 'opal_util_init_sys_limits':
../../../opal/util/sys_limits.c:107:20: warning: 'lim' may be used 
uninitialized in this function

  CC mca_base_param.lo
../../../../opal/mca/base/mca_base_param.c: In function 'register_param':
../../../../opal/mca/base/mca_base_param.c:113:25: warning: 'var_type' may be 
used uninitialized in this function

  CC mca_base_var.lo
../../../../opal/mca/base/mca_base_var.c: In function 'var_set_from_string':
../../../../opal/mca/base/mca_base_var.c:797:14: warning: 'int_value' may be 
used uninitialized in this function
../../../../opal/mca/base/mca_base_var.c: In function 'mca_base_var_dump':
../../../../opal/mca/base/mca_base_var.c:2016:27: warning: 'original' may be 
used uninitialized in this function
../../../../opal/mca/base/mca_base_var.c:2015:30: warning: 'synonyms' may be 
used uninitialized in this function
../../../../opal/mca/base/mca_base_var.c:2018:17: warning: 'type_string' may be 
used uninitialized in this function

  CC runtime/opal_info_support.lo
../../opal/runtime/opal_info_support.c: In function 
'opal_info_register_project_frameworks':
../../opal/runtime/opal_info_support.c:241:12: warning: 'rc' may be used 
uninitialized in this function

  CC base/oob_base_init.lo
../../../../orte/mca/oob/base/oob_base_init.c: In function 'mca_oob_base_init':
../../../../orte/mca/oob/base/oob_base_init.c:55:43: warning: 's_component' may 
be used uninitialized in this function

  CC ras_slurm_module.lo
../../../../../orte/mca/ras/slurm/ras_slurm_module.c: In function 'init':
../../../../../orte/mca/ras/slurm/ras_slurm_module.c:143:11: warning: 
'slurm_host' may be used uninitialized in this function
../../../../../orte/mca/ras/slurm/ras_slurm_module.c:144:14: warning: 'port' 
may be used uninitialized in this function
../../../../../orte/mca/ras/slurm/ras_slurm_module.c: In function 'recv_data':
../../../../../orte/mca/ras/slurm/ras_slurm_module.c:742:31: warning: 'jtrk' 
may be used uninitialized in this function
../../../../../orte/mca/ras/slurm/ras_slurm_module.c:740:17: warning: 'idx' may 
be used uninitialized in this function
../../../../../orte/mca/ras/slurm/ras_slurm_module.c:740:22: warning: 'sjob' 
may be used uninitialized in this function
../../../../../orte/mca/ras/slurm/ras_slurm_module.c:741:20: warning: 
'nodelist' may be used uninitialized in this function

  CC rmaps_lama_params.lo
../../../../../orte/mca/rmaps/lama/rmaps_lama_params.c: In function 
'rmaps_lama_ok_to_prune_level':
../../../../../orte/mca/rmaps/lama/rmaps_lama_params.c:789:19: warning: 
comparison between 'rmaps_lama_order_type_t' and 'rmaps_lama_level_type_t'
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[OMPI devel] Openib + common/verbs CPC consolidation

[Jeff Squyres (jsquyres)]

FYI: On the teleconf today, we talked about the next dominos to fall in the 
quest to move the BTLs down to OPAL:

1. Nathan will make the openib "udcm" CPC the default in the immediate future
   --> This paves the way to ditch the problematic "oob" openib CPC
   --> This also will give udcm more widespread testing
2. Mellanox will add XRC support to udcm
   --> This paves the way to ditch the problematic "xoob" openib CPC
   --> Josh thought they could do this within a month, but that's a SWAG and 
subject to change
3. I will ping Chelsio about getting them to add proper iWARP support into 
common/ofacm
   --> This paves the way to eliminate btl/openib/cpc
   --> No idea on timeframe yet
4. Once #3 is done, make openib use common/ofacm
5. Once #2, #3, and #4 are done, delete btl/openib/cpc

#1-3 have people assigned to them.  #4 does not (#5 is pretty trivial -- an svn 
rm plus some Makefile.am mods).

-- 
Jeff Squyres
jsquy...@cisco.com
For corporate legal information go to: 
http://www.cisco.com/web/about/doing_business/legal/cri/

Re: [hwloc-devel] stop embedding libltdl

[Brice Goglin]

Here's a patch that seems to work. I stole the code that libtool.m4 uses
to find ltdl dependencies, put it inside a new HWLOC_CHECK_LTDL_DEPS
that stores these dependencies in HWLOC_LIBS_PRIVATE. It properly adds
-ldl on Linux and nothing on FreeBSD.

The rest of the patch is similar to Jeff's, with things moved inside
HWLOC_SETUP_CORE.

Brice




Le 14/05/2013 10:27, Brice Goglin a écrit :
> I am reviving this thread since I interrupted it to discuss "enabling
> plugins vs embedding hwloc" (1) but we didn't close the discussion
> about "not embedding libltdl anymore" (2).
>
> We committed a fix for (1) that (sometimes) generates tarballs without
> src/libltdl directory. It doesn't always happen, I don't understand
> why, but it certainly makes those tarballs unusable (configure
> complains that a Makefile.in is missing). My original patch for (1)
> fixed the problem, but (2) is a better way to avoid any such issue.
>
> The patch below does pretty much what we need, except putting the
> right ltdl static libs in hwloc.pc
>
> I am going to look at this before releasing v1.7.1
>
> Brice
>
>
>
>
> Le 08/05/2013 02:47, Jeff Squyres (jsquyres) a écrit :
>> How's this patch?
>>
>> The only question I have is: how do we figure out what libraries to put in 
>> the .pc file in the --disable-shared --enable-static case?
>>
>>
>> On May 7, 2013, at 8:24 PM, Samuel Thibault  wrote:
>>
>>> > Jeff Squyres (jsquyres), le Wed 08 May 2013 02:21:02 +0200, a écrit :
 >> On May 7, 2013, at 6:25 PM, Brice Goglin  wrote:
 >> 
> >>> I don't have anything against this. What was the reason for not using
> >>> the default/system libltdl in OMPI? libtool was buggy when you started
> >>> using it?
 >> 
 >> 
 >> I neglected to answer this.
 >> 
 >> Yes, plus libltdl grew new functionality that we needed (global/local 
 >> symbol visibility).
 >> 
 >> We might be getting to the point soon where we can rely on the 
 >> installed libltdl to be new enough everywhere, but we haven't had that 
 >> conversation.
>>> > 
>>> > We could already check that the installed version is new enough for our
>>> > needs.
>>> > 
>>> > Samuel
>>> > ___
>>> > hwloc-devel mailing list
>>> > hwloc-de...@open-mpi.org
>>> > http://www.open-mpi.org/mailman/listinfo.cgi/hwloc-devel
>> -- Jeff Squyres jsquy...@cisco.com For corporate legal information go
>> to: http://www.cisco.com/web/about/doing_business/legal/cri/
>>
>> no-embed-libltdl.diff
>>
>>
>> Index: configure.ac
>> ===
>> --- configure.ac (revision 5606)
>> +++ configure.ac (working copy)
>> @@ -168,30 +168,25 @@
>>  AM_DISABLE_STATIC
>>  AM_PROG_LIBTOOL([dlopen win32-dll])
>>  LT_LANG([C])
>> -LT_CONFIG_LTDL_DIR([src/libltdl])
>> -LTDL_INIT([recursive convenience])
>> -AC_CONFIG_FILES([src/libltdl/Makefile])
>>  
>> -# Workarounds for libtool LT_CONFIG_H bug
>> -#CPPFLAGS="$CPPFLAGS -I$HWLOC_top_builddir"
>> -AC_CONFIG_COMMANDS_PRE([LT_CONFIG_H=`expr "$LT_CONFIG_H" : '.*/\(.*\)'`])
>> +# If we want plugins, look for ltdl.h and libltdl
>> +LIBLTDL=
>> +AS_IF([test "$enable_plugins" = "yes"],
>> +  [AC_CHECK_HEADER([ltdl.h], [],
>> +  [AC_MSG_WARN([Plugin support requested, but could not find 
>> ltdl.h])
>> +   AC_MSG_ERROR([Cannot continue])])
>> +   AC_CHECK_LIB([ltdl], [lt_dlopenext], [],
>> +  [AC_MSG_WARN([Plugin support requested, but could not find 
>> libltdl])
>> +   AC_MSG_ERROR([Cannot continue])])
>> +  ])
>> +AC_SUBST(LIBLTDL)
>>  
>>  # Add libltdl static-build dependencies to hwloc.pc
>>  if test "x$hwloc_have_plugins" = xyes; then
>> -  if test "x$with_included_ltdl" = xno; then
>> -HWLOC_LIBS_PRIVATE="$HWLOC_LIBS_PRIVATE $LIBLTDL"
>> -  fi
>> +  # JMS What to put here for static builds?
>>HWLOC_LIBS_PRIVATE="$HWLOC_LIBS_PRIVATE $lt_cv_dlopen_libs"
>>  fi
>>  
>> -# Is ltdl included?
>> -HWLOC_LTDL_SUBDIR=
>> -AS_IF([test "x$with_included_ltdl" = xyes],
>> -  [HWLOC_LIBLTDL_SUBDIR=libltdl])
>> -AC_SUBST(HWLOC_LIBLTDL_SUBDIR)
>> -dnl AM_CONDITIONAL([HWLOC_LTDL_INCLUDED], [test "x$with_included_ltdl" = 
>> xyes])
>> -
>> -
>>  # Party on
>>  AC_OUTPUT
>>  
>> Index: src
>> ===
>> --- src  (revision 5606)
>> +++ src  (working copy)
>>
>> Property changes on: src
>> ___
>> Modified: svn:ignore
>> ## -1,5 +1,4 ##
>>  .deps
>>  Makefile.in
>>  Makefile
>> -libltdl
>>  static-components.h
>> Index: src/Makefile.am
>> ===
>> --- src/Makefile.am  (revision 5606)
>> +++ src/Makefile.am  (working copy)
>> @@ -207,8 +207,6 @@
>>  AM_CPPFLAGS += $(LTDLINCL)
>>  libhwloc_la_LDFLAGS += -export-dynamic
>>  libhwloc_la_LIBADD = 

[hwloc-devel] stop embedding libltdl

[Brice Goglin]

I am reviving this thread since I interrupted it to discuss "enabling
plugins vs embedding hwloc" (1) but we didn't close the discussion about
"not embedding libltdl anymore" (2).

We committed a fix for (1) that (sometimes) generates tarballs without
src/libltdl directory. It doesn't always happen, I don't understand why,
but it certainly makes those tarballs unusable (configure complains that
a Makefile.in is missing). My original patch for (1) fixed the problem,
but (2) is a better way to avoid any such issue.

The patch below does pretty much what we need, except putting the right
ltdl static libs in hwloc.pc

I am going to look at this before releasing v1.7.1

Brice




Le 08/05/2013 02:47, Jeff Squyres (jsquyres) a écrit :
> How's this patch?
>
> The only question I have is: how do we figure out what libraries to put in 
> the .pc file in the --disable-shared --enable-static case?
>
>
> On May 7, 2013, at 8:24 PM, Samuel Thibault  wrote:
>
>> > Jeff Squyres (jsquyres), le Wed 08 May 2013 02:21:02 +0200, a écrit :
>>> >> On May 7, 2013, at 6:25 PM, Brice Goglin  wrote:
>>> >> 
 >>> I don't have anything against this. What was the reason for not using
 >>> the default/system libltdl in OMPI? libtool was buggy when you started
 >>> using it?
>>> >> 
>>> >> 
>>> >> I neglected to answer this.
>>> >> 
>>> >> Yes, plus libltdl grew new functionality that we needed (global/local 
>>> >> symbol visibility).
>>> >> 
>>> >> We might be getting to the point soon where we can rely on the installed 
>>> >> libltdl to be new enough everywhere, but we haven't had that 
>>> >> conversation.
>> > 
>> > We could already check that the installed version is new enough for our
>> > needs.
>> > 
>> > Samuel
>> > ___
>> > hwloc-devel mailing list
>> > hwloc-de...@open-mpi.org
>> > http://www.open-mpi.org/mailman/listinfo.cgi/hwloc-devel
> -- Jeff Squyres jsquy...@cisco.com For corporate legal information go
> to: http://www.cisco.com/web/about/doing_business/legal/cri/
>
> no-embed-libltdl.diff
>
>
> Index: configure.ac
> ===
> --- configure.ac  (revision 5606)
> +++ configure.ac  (working copy)
> @@ -168,30 +168,25 @@
>  AM_DISABLE_STATIC
>  AM_PROG_LIBTOOL([dlopen win32-dll])
>  LT_LANG([C])
> -LT_CONFIG_LTDL_DIR([src/libltdl])
> -LTDL_INIT([recursive convenience])
> -AC_CONFIG_FILES([src/libltdl/Makefile])
>  
> -# Workarounds for libtool LT_CONFIG_H bug
> -#CPPFLAGS="$CPPFLAGS -I$HWLOC_top_builddir"
> -AC_CONFIG_COMMANDS_PRE([LT_CONFIG_H=`expr "$LT_CONFIG_H" : '.*/\(.*\)'`])
> +# If we want plugins, look for ltdl.h and libltdl
> +LIBLTDL=
> +AS_IF([test "$enable_plugins" = "yes"],
> +  [AC_CHECK_HEADER([ltdl.h], [],
> +  [AC_MSG_WARN([Plugin support requested, but could not find ltdl.h])
> +   AC_MSG_ERROR([Cannot continue])])
> +   AC_CHECK_LIB([ltdl], [lt_dlopenext], [],
> +  [AC_MSG_WARN([Plugin support requested, but could not find 
> libltdl])
> +   AC_MSG_ERROR([Cannot continue])])
> +  ])
> +AC_SUBST(LIBLTDL)
>  
>  # Add libltdl static-build dependencies to hwloc.pc
>  if test "x$hwloc_have_plugins" = xyes; then
> -  if test "x$with_included_ltdl" = xno; then
> -HWLOC_LIBS_PRIVATE="$HWLOC_LIBS_PRIVATE $LIBLTDL"
> -  fi
> +  # JMS What to put here for static builds?
>HWLOC_LIBS_PRIVATE="$HWLOC_LIBS_PRIVATE $lt_cv_dlopen_libs"
>  fi
>  
> -# Is ltdl included?
> -HWLOC_LTDL_SUBDIR=
> -AS_IF([test "x$with_included_ltdl" = xyes],
> -  [HWLOC_LIBLTDL_SUBDIR=libltdl])
> -AC_SUBST(HWLOC_LIBLTDL_SUBDIR)
> -dnl AM_CONDITIONAL([HWLOC_LTDL_INCLUDED], [test "x$with_included_ltdl" = 
> xyes])
> -
> -
>  # Party on
>  AC_OUTPUT
>  
> Index: src
> ===
> --- src   (revision 5606)
> +++ src   (working copy)
>
> Property changes on: src
> ___
> Modified: svn:ignore
> ## -1,5 +1,4 ##
>  .deps
>  Makefile.in
>  Makefile
> -libltdl
>  static-components.h
> Index: src/Makefile.am
> ===
> --- src/Makefile.am   (revision 5606)
> +++ src/Makefile.am   (working copy)
> @@ -207,8 +207,6 @@
>  AM_CPPFLAGS += $(LTDLINCL)
>  libhwloc_la_LDFLAGS += -export-dynamic
>  libhwloc_la_LIBADD = $(LIBLTDL)
> -libhwloc_la_DEPENDENCIES = $(LTDLDEPS)
> -SUBDIRS = $(HWLOC_LIBLTDL_SUBDIR)
>  endif
>  
>  # Embedded library (note the lack of a .so version number -- that
>
>
> ___
> hwloc-devel mailing list
> hwloc-de...@open-mpi.org
> http://www.open-mpi.org/mailman/listinfo.cgi/hwloc-devel

[OMPI devel] RFC: rewrite of ORTE OOB

[Ralph Castain]

Hi folks

As most of you know, I have been working for quite some time on rewriting the 
OOB. It is now getting close to being ready to be committed.

Unfortunately, I am changing jobs on May 20th (starting a position at Intel) 
that will cause a hopefully short "service interruption" in my ability to 
contribute code to OMPI. I have started the legal paperwork to resolve that 
situation and have the backing of my new management, but these things always 
take time.

Ordinarily, I would simply hold off the commit until the paperwork was 
completed. However, after talking with a few people in the community, the 
changes are important and desirable enough to get this into the trunk without 
the indefinite delay. I can continue to help debug even after my status changes 
- just cannot directly contribute code. So I have committed the code to the 
OMPI repository in a public temporary branch. Once the community believes the 
code is ready, Jeff can merge it back to the trunk if I'm not able to do so.


WHAT:Rewrite of ORTE OOB

WHY:   Support asynchronous progress and a host of other features

WHEN:TBD (will discuss at weekly telecon and/or on mailing list)

SYNOPSIS:
The current OOB has served us well, but a number of limitations have been 
identified over the years. Specifically:

* it is only progressed when called via opal_progress, which can lead to hangs 
or recursive calls into libevent (which is not supported by that code)

* we've had issues when multiple NICs are available as the code doesn't "shift" 
messages between transports - thus, all nodes had to be available via the same 
TCP interface.

* the OOB "unloads" incoming opal_buffer_t objects during the transmission, 
thus preventing use of OBJ_RETAIN in the code when repeatedly sending the same 
message to multiple recipients

* there is no failover mechanism across NICs - if the selected NIC (or its 
attached switch) fails, we are forced to abort

* only one transport (i.e., component) can be "active"


The revised OOB resolves these problems:

* async progress is used for all application processes, with the progress 
thread blocking in the event library

* each available NIC is supported by its own TCP module. The ability to 
asynchronously progress each module independently is provided, but not enabled 
by default (a runtime MCA parameter turns it "on")

* multi-address NICs (e.g., a NIC with both an IPv4 and IPv6 address, or with 
virtual interfaces) are supported - reachability is determined by comparing the 
contact info for a peer against all addresses within the range covered by the 
address/mask pairs for the NIC.

* a message that arrives on one NIC is automatically shifted to whatever NIC 
that is connected to the next "hop" if that peer cannot be reached by the 
incoming NIC. If no TCP module will reach the peer, then the OOB attempts to 
send the message via all other available components - if none can reach the 
peer, then an "error" is reported back to the RML, which then calls the errmgr 
for instructions.

* opal_buffer_t now conforms to standard object rules re OBJ_RETAIN as we no 
longer "unload" the incoming object

* NIC failure is reported to the TCP component, which then tries to resend the 
message across any other available TCP NIC. If that doesn't work, then the 
message is given back to the OOB base to try using other components. If all 
that fails, then the error is reported to the RML, which reports to the errmgr 
for instructions

* obviously from the above, multiple OOB components (e.g., TCP and UD) can be 
active in parallel

* the matching code has been moved to the RML (and out of the OOB/TCP 
component) so it is independent of transport

* routing is done by the individual OOB modules (as opposed to the RML). Thus, 
both routed and non-routed transports can simultaneously be active

* all blocking send/recv APIs have been removed. Everything operates 
asynchronously.


KNOWN LIMITATIONS:

* although provision is made for component failover as described above, the 
code for doing so has not been implemented yet. At the moment, if all 
connections for a given component fail, the errmgr is notified of a "lost 
connection", which by default results in termination of the job if it was a 
lifeline

* the IPv6 code is present and compiles, but has not been tested as I don't 
have access to any IPv6-enabled cluster

* routing is performed at the individual module level, yet the active routed 
component is selected on a global basis. We probably should update that to 
reflect that different transports may need/choose to route in different ways

* obviously, not every error path has been tested nor necessarily covered

* determining abnormal termination is more challenging than in the old code as 
we now potentially have multiple ways of connecting to a process. Ideally, we 
would declare "connection failed" when *all* transports can no longer reach the 
process, but that requires some additional (possibly