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Josh Hursey
3b4073e32c This commit fixes the checkpoint/restart functionality on the trunk. Included in this commit are:
* Extension to the ESS framework to support C/R
 * Fixed support for {{{snapc_base_establish_global_snapshot_dir}}}
 * Fixed FileM support
 * Misc. minor code modifications

There are some outstanding visability issues that I want to fix next.

This commit was SVN r17725.
2008-03-05 04:57:23 +00:00
Ralph Castain
d70e2e8c2b Merge the ORTE devel branch into the main trunk. Details of what this means will be circulated separately.
Remains to be tested to ensure everything came over cleanly, so please continue to withhold commits a little longer

This commit was SVN r17632.
2008-02-28 01:57:57 +00:00
Josh Hursey
7437f37e96 This commit contains the following:
* Fix some missing includes in a few places.
 * Add the cr_request() functionality to the BLCR CRS component.
   We are now dependent upon the 0.6.* series of BLCR.
 * Made the CR notification mechanism a registered function.
   This way we can have an OPAL-only version and it can be replaced at
   runtime with the ORTE version.
 * Add a 'opal_cr_allow_opal_only' parameter that will enable OPAL-only
   CR functionality when the user wants it. Default: Disabled.
 * Fix the placement of a checkpoint request check in MPI_Init
 * Pull the OPAL notification mechanism into the SnapC framework.
   * We no longer fork/exec the 'opal-checkpoint' command for local
   checkpointing, the Local coordinator in the orted does this directly.
   * The Local and Application coordinator talk together bypassing the OPAL
   notifiation mechanism.
   * Optimized the Local <-> App Coordinator communication.
   * Improved the structure used to track vpid_snapshots in the local coord.
 * Fix a race condition in which an application under heavy communication load
   may produce an inconsistent global checkpoint.

This commit was SVN r16389.
2007-10-08 20:53:02 +00:00
Ralph Castain
54b2cf747e These changes were mostly captured in a prior RFC (except for #2 below) and are aimed specifically at improving startup performance and setting up the remaining modifications described in that RFC.
The commit has been tested for C/R and Cray operations, and on Odin (SLURM, rsh) and RoadRunner (TM). I tried to update all environments, but obviously could not test them. I know that Windows needs some work, and have highlighted what is know to be needed in the odls process component.

This represents a lot of work by Brian, Tim P, Josh, and myself, with much advice from Jeff and others. For posterity, I have appended a copy of the email describing the work that was done:

As we have repeatedly noted, the modex operation in MPI_Init is the single greatest consumer of time during startup. To-date, we have executed that operation as an ORTE stage gate that held the process until a startup message containing all required modex (and OOB contact info - see #3 below) info could be sent to it. Each process would send its data to the HNP's registry, which assembled and sent the message when all processes had reported in.

In addition, ORTE had taken responsibility for monitoring process status as it progressed through a series of "stage gates". The process reported its status at each gate, and ORTE would then send a "release" message once all procs had reported in.

The incoming changes revamp these procedures in three ways:

1. eliminating the ORTE stage gate system and cleanly delineating responsibility between the OMPI and ORTE layers for MPI init/finalize. The modex stage gate (STG1) has been replaced by a collective operation in the modex itself that performs an allgather on the required modex info. The allgather is implemented using the orte_grpcomm framework since the BTL's are not active at that point. At the moment, the grpcomm framework only has a "basic" component analogous to OMPI's "basic" coll framework - I would recommend that the MPI team create additional, more advanced components to improve performance of this step.

The other stage gates have been replaced by orte_grpcomm barrier functions. We tried to use MPI barriers instead (since the BTL's are active at that point), but - as we discussed on the telecon - these are not currently true barriers so the job would hang when we fell through while messages were still in process. Note that the grpcomm barrier doesn't actually resolve that problem, but Brian has pointed out that we are unlikely to ever see it violated. Again, you might want to spend a little time on an advanced barrier algorithm as the one in "basic" is very simplistic.

Summarizing this change: ORTE no longer tracks process state nor has direct responsibility for synchronizing jobs. This is now done via collective operations within the MPI layer, albeit using ORTE collective communication services. I -strongly- urge the MPI team to implement advanced collective algorithms to improve the performance of this critical procedure.


2. reducing the volume of data exchanged during modex. Data in the modex consisted of the process name, the name of the node where that process is located (expressed as a string), plus a string representation of all contact info. The nodename was required in order for the modex to determine if the process was local or not - in addition, some people like to have it to print pretty error messages when a connection failed.

The size of this data has been reduced in three ways:

(a) reducing the size of the process name itself. The process name consisted of two 32-bit fields for the jobid and vpid. This is far larger than any current system, or system likely to exist in the near future, can support. Accordingly, the default size of these fields has been reduced to 16-bits, which means you can have 32k procs in each of 32k jobs. Since the daemons must have a vpid, and we require one daemon/node, this also restricts the default configuration to 32k nodes.

To support any future "mega-clusters", a configuration option --enable-jumbo-apps has been added. This option increases the jobid and vpid field sizes to 32-bits. Someday, if necessary, someone can add yet another option to increase them to 64-bits, I suppose.

(b) replacing the string nodename with an integer nodeid. Since we have one daemon/node, the nodeid corresponds to the local daemon's vpid. This replaces an often lengthy string with only 2 (or at most 4) bytes, a substantial reduction.

(c) when the mca param requesting that nodenames be sent to support pretty error messages, a second mca param is now used to request FQDN - otherwise, the domain name is stripped (by default) from the message to save space. If someone wants to combine those into a single param somehow (perhaps with an argument?), they are welcome to do so - I didn't want to alter what people are already using.

While these may seem like small savings, they actually amount to a significant impact when aggregated across the entire modex operation. Since every proc must receive the modex data regardless of the collective used to send it, just reducing the size of the process name removes nearly 400MBytes of communication from a 32k proc job (admittedly, much of this comm may occur in parallel). So it does add up pretty quickly.


3. routing RML messages to reduce connections. The default messaging system remains point-to-point - i.e., each proc opens a socket to every proc it communicates with and sends its messages directly. A new option uses the orteds as routers - i.e., each proc only opens a single socket to its local orted. All messages are sent from the proc to the orted, which forwards the message to the orted on the node where the intended recipient proc is located - that orted then forwards the message to its local proc (the recipient). This greatly reduces the connection storm we have encountered during startup.

It also has the benefit of removing the sharing of every proc's OOB contact with every other proc. The orted routing tables are populated during launch since every orted gets a map of where every proc is being placed. Each proc, therefore, only needs to know the contact info for its local daemon, which is passed in via the environment when the proc is fork/exec'd by the daemon. This alone removes ~50 bytes/process of communication that was in the current STG1 startup message - so for our 32k proc job, this saves us roughly 32k*50 = 1.6MBytes sent to 32k procs = 51GBytes of messaging.

Note that you can use the new routing method by specifying -mca routed tree - if you so desire. This mode will become the default at some point in the future.


There are a few minor additional changes in the commit that I'll just note in passing:

* propagation of command line mca params to the orteds - fixes ticket #1073. See note there for details.

* requiring of "finalize" prior to "exit" for MPI procs - fixes ticket #1144. See note there for details.

* cleanup of some stale header files

This commit was SVN r16364.
2007-10-05 19:48:23 +00:00
Jeff Squyres
8f10c285ef Fix Coverity CID 466: remove unused variable / dead code.
This commit was SVN r15998.
2007-08-29 01:25:03 +00:00
Brian Barrett
39a6057fc6 A number of improvements / changes to the RML/OOB layers:
* General TCP cleanup for OPAL / ORTE
  * Simplifying the OOB by moving much of the logic into the RML
  * Allowing the OOB RML component to do routing of messages
  * Adding a component framework for handling routing tables
  * Moving the xcast functionality from the OOB base to its own framework

Includes merge from tmp/bwb-oob-rml-merge revisions:

    r15506, r15507, r15508, r15510, r15511, r15512, r15513

This commit was SVN r15528.

The following SVN revisions from the original message are invalid or
inconsistent and therefore were not cross-referenced:
  r15506
  r15507
  r15508
  r15510
  r15511
  r15512
  r15513
2007-07-20 01:34:02 +00:00
Brian Barrett
508da4e959 OS X apparently really doesn't like shared libraries with unresolvable
symbols in them and environ is defined only in the final application
(probably in crt1.o).  Apple provides a function for getting at the
environment, so use that instead if it's available.

This commit was SVN r14857.
2007-06-05 03:03:59 +00:00
Josh Hursey
596062d34b Seems that the recent changes in the sds and oob exposed some invalid
assumptions in the FT restart code for the ORTE layer.

This fixes those problems by having the RML completely shutdown and 
restart the OOB framework (instead of just the module as before).
This makes it much easier to manage, and maintainable as the OOB
changes in the future.

The SDS now does communication as part of its startup procedure, so
we need to make sure we restart the RML before the SDS so that it can
communicate properly.

OOB base [close|open] used a static bool to determine if they have
been called previously or not. I needed to expose this boolean so 
that I can close() then open() the oob base in the restart procedure.
The functionality has not changed, we just now have the ability to 
open/close the framework as many times as we need to as long as we
always call them in that order. (So calling open twice in a row is not allowed
as before, it is only allowed if you open(), close(), then open() again).

Things seem to be working now.

This commit was SVN r14515.
2007-04-25 19:51:52 +00:00
George Bosilca
f2a6b9394f Deal with the include spree. Protect "environ" on Windows.
Some others minors modifications in order to make it
compile [again] on Windows.

This commit was SVN r14188.
2007-04-01 16:16:54 +00:00
Josh Hursey
dadca7da88 Merging in the jjhursey-ft-cr-stable branch (r13912 : HEAD).
This merge adds Checkpoint/Restart support to Open MPI. The initial
frameworks and components support a LAM/MPI-like implementation.

This commit follows the risk assessment presented to the Open MPI core
development group on Feb. 22, 2007.

This commit closes trac:158

More details to follow.

This commit was SVN r14051.

The following SVN revisions from the original message are invalid or
inconsistent and therefore were not cross-referenced:
  r13912

The following Trac tickets were found above:
  Ticket 158 --> https://svn.open-mpi.org/trac/ompi/ticket/158
2007-03-16 23:11:45 +00:00