Re: openMPI vs openMosix
"Wes Wagner" <[email protected]> Mon, 25 Jun 2007 09:25:31 -0700
| Newsgroups | gmane.linux.cluster.openmosix.general |
|---|---|
| Message-ID | <[email protected]> |
--===============0584737832== Content-Type: multipart/alternative; boundary="----=_Part_25053_7371807.1182788731653" ------=_Part_25053_7371807.1182788731653 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Content-Disposition: inline Is this not a classic, use the right tool for the right job issue? If you need massive scalable symmetric multi-processing, using a large SMP machine. If you can and need to do massive parallel multiple independent processes that share nothing, use a cluster or batch processing system. If you can't afford a massive SMP system, redefine the problem.. ? -Wes On 6/25/07, Moshe Bar <[email protected]> wrote: > > not only is the normal RAM access a full 3 to 4 orders of magnitude > faster, but also there is simulatenous access to cache lines > resolution, whereas a shared mem implementation has to relay on the > MMU, which only does 4096 bytes as a minimum, which vastly increases > the true and false sharing conflicts. > > To have a NIC help with that it would have to do something like RDMA, > with (at the least) MMU protection synced with the MMUs of all > connected nodes and remote interrupt capability. I doubt, however, > that such a dream NIC would help much in terms of performance. This > would be very close to the Altix solution, and witness their problems: > nodes have to be very close to each other (max 2 or 3 feet I think), > and > > On 6/25/07, Christian Leber <[email protected]> wrote: > > On Mon, Jun 25, 2007 at 10:41:24AM -0500, Moshe Bar wrote: > > > we used to have it. Shared memory without hardware support very > > > severely limits the types of apps that will actually scale. Even sgi > > > in their altix machines (which are essentiallys shared memory > > > machines) have very limited scalability for a lot of apps, if not > > > most. > > > > What hardware features would be desireable to have in a NIC to be able > > to implement shared memory halfway fast for Mosix on page level? > > > > Regards > > Christian Leber > > > > -- > > http://rettetdieti.vde-uni-mannheim.de/ > > > > > > > ------------------------------------------------------------------------- > > This SF.net email is sponsored by DB2 Express > > Download DB2 Express C - the FREE version of DB2 express and take > > control of your XML. No limits. Just data. Click to get it now. > > http://sourceforge.net/powerbar/db2/ > > _______________________________________________ > > openMosix-general mailing list > > openMosix-general-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org > > https://lists.sourceforge.net/lists/listinfo/openmosix-general > > > > ------------------------------------------------------------------------- > This SF.net email is sponsored by DB2 Express > Download DB2 Express C - the FREE version of DB2 express and take > control of your XML. No limits. Just data. Click to get it now. > http://sourceforge.net/powerbar/db2/ > _______________________________________________ > openMosix-general mailing list > openMosix-general-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org > https://lists.sourceforge.net/lists/listinfo/openmosix-general > -- Wes Wagner Join a libertarian network of person-to-person lending on Prosper: http://www.prosper.com/groups/group_home.aspx?group_short_name=freelibertarians&referrer=AiriusTorpora&utm_source=referrer-AiriusTorpora&utm_medium=referral-link&utm_content=join_my_group-160x33&utm_campaign=referrals-group ------=_Part_25053_7371807.1182788731653 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Content-Disposition: inline Is this not a classic, use the right tool for the right job issue? If you need massive scalable symmetric multi-processing, using a large SMP machine. If you can and need to do massive parallel multiple independent processes that share nothing, use a cluster or batch processing system. <br><br>If you can't afford a massive SMP system, redefine the problem.. ?<br><br>-Wes<br><br><br><div><span class="gmail_quote">On 6/25/07, <b class="gmail_sendername">Moshe Bar</b> <<a href="mailto:[email protected]"> [email protected]</a>> wrote:</span><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">not only is the normal RAM access a full 3 to 4 orders of magnitude <br>faster, but also there is simulatenous access to cache lines<br>resolution, whereas a shared mem implementation has to relay on the<br>MMU, which only does 4096 bytes as a minimum, which vastly increases<br>the true and false sharing conflicts. <br><br>To have a NIC help with that it would have to do something like RDMA,<br>with (at the least) MMU protection synced with the MMUs of all<br>connected nodes and remote interrupt capability. I doubt, however,<br>that such a dream NIC would help much in terms of performance. This <br>would be very close to the Altix solution, and witness their problems:<br>nodes have to be very close to each other (max 2 or 3 feet I think),<br>and<br><br>On 6/25/07, Christian Leber <<a href="mailto:[email protected]"> [email protected]</a>> wrote:<br>> On Mon, Jun 25, 2007 at 10:41:24AM -0500, Moshe Bar wrote:<br>> > we used to have it. Shared memory without hardware support very<br>> > severely limits the types of apps that will actually scale. Even sgi <br>> > in their altix machines (which are essentiallys shared memory<br>> > machines) have very limited scalability for a lot of apps, if not<br>> > most.<br>><br>> What hardware features would be desireable to have in a NIC to be able <br>> to implement shared memory halfway fast for Mosix on page level?<br>><br>> Regards<br>> Christian Leber<br>><br>> --<br>> <a href="http://rettetdieti.vde-uni-mannheim.de/">http://rettetdieti.vde-uni-mannheim.de/ </a><br>><br>><br>> -------------------------------------------------------------------------<br>> This SF.net email is sponsored by DB2 Express<br>> Download DB2 Express C - the FREE version of DB2 express and take <br>> control of your XML. No limits. Just data. Click to get it now.<br>> <a href="http://sourceforge.net/powerbar/db2/">http://sourceforge.net/powerbar/db2/</a><br>> _______________________________________________ <br>> openMosix-general mailing list<br>> <a href="mailto:openMosix-general-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org">openMosix-general-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org</a><br>> <a href="https://lists.sourceforge.net/lists/listinfo/openmosix-general"> https://lists.sourceforge.net/lists/listinfo/openmosix-general</a><br>><br><br>-------------------------------------------------------------------------<br>This SF.net email is sponsored by DB2 Express<br>Download DB2 Express C - the FREE version of DB2 express and take <br>control of your XML. No limits. Just data. Click to get it now.<br><a href="http://sourceforge.net/powerbar/db2/">http://sourceforge.net/powerbar/db2/</a><br>_______________________________________________<br>openMosix-general mailing list <br><a href="mailto:openMosix-general-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org">openMosix-general-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org</a><br><a href="https://lists.sourceforge.net/lists/listinfo/openmosix-general">https://lists.sourceforge.net/lists/listinfo/openmosix-general </a><br></blockquote></div><br><br clear="all"><br>-- <br>Wes Wagner<br><br>Join a libertarian network of person-to-person lending on Prosper:<br> <br><a href="http://www.prosper.com/groups/group_home.aspx?group_short_name=freelibertarians&referrer=AiriusTorpora&utm_source=referrer-AiriusTorpora&utm_medium=referral-link&utm_content=join_my_group-160x33&utm_campaign=referrals-group"> http://www.prosper.com/groups/group_home.aspx?group_short_name=freelibertarians&referrer=AiriusTorpora&utm_source=referrer-AiriusTorpora&utm_medium=referral-link&utm_content=join_my_group-160x33&utm_campaign=referrals-group </a> ------=_Part_25053_7371807.1182788731653-- --===============0584737832== Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline ------------------------------------------------------------------------- This SF.net email is sponsored by DB2 Express Download DB2 Express C - the FREE version of DB2 express and take control of your XML. No limits. Just data. Click to get it now. http://sourceforge.net/powerbar/db2/ --===============0584737832== Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline _______________________________________________ openMosix-general mailing list openMosix-general-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org https://lists.sourceforge.net/lists/listinfo/openmosix-general --===============0584737832==--