Re: [SSI-users] ssi on podcast

[Roger T. <rog...@gm...>]

FYI: http://wiki.openssi.org/go/Features

OpenSSI has been known to support Infiniband (IP over IB).  Stan Smith has
used OpenSSI with Infiniband.  However our CVS code respository at
SourceForge contains a new optimization for CFS over TCP/IP - an internal
CFS read/write cache but this optimization can be disabled for Infiniband.
SHM is not affected.

OpenSSI provides a single IPC namespace.  If I remember correctly, the
single namespace means shared memory segments are accessible cluster-wide
(see below).  These SHM segments do migrate but only during process
migration of the owning process.  The load-balancing of just SHM segments
(without process migration) is not implemented.

In OpenSSI, procfs provides an extra column: node_num.  All IPC entities in
the cluster are visible.

$ cat /proc/sysvipc/shm
   key      shmid perms       size  cpid  lpid nattch   uid   gid  cuid
cgid      atime      dtime      ctime       view   node_num
         0    1671168  1666     294912 200617 200620     10     0     0
0   0 1346607713 1346607607 1346607603    default          3
         0    1572876  1666     294912 69603 69606      9     0     0     0
0 1346607713 1346587446 1346473273    default          1

$ cat /proc/sysvipc/sem
       key      semid perms      nsems   uid   gid  cuid  cgid
otime      ctime       view    node_num
         0    4947968   666          1     0     0     0     0 1346639170
1346607607    default          3
         0    3997698   666          1     0     0     0     0 1346639050
1346587447    default          1



On Sun, Aug 26, 2012 at 5:46 PM, Vincent Diepeveen <di...@xs...> wrote:

> Brock,
>
> If we may be honest about SSI in general:
>
> For my 8 node $200 a box cluster having a SSI would be really GREAT.
> And i can't use big enough capital letters for it.
>
> For HPC with big supercomputers it's total nonsense to do things in a
> semi-centralized manner.
>
> Yet where it is interesting to make 1 big supercomputer out of my
> $3200 set of 8 machines
> which eat together by the way around 1.4 kilowatt under full load, so
> that's similar to a
> 8 socket machine of $200k.
>
> Now latest 8 socket machines sure are faster than this 64 cores i
> have here,
> yet realize the price i paid for them.
>
> So it would be as powerful nearly as a 8 socket machine
> given the right software and decent interconnects.
>
> So you want the choice of which interconnect to use, to take that
> yourself.
>
> Let me assure you that built in ethernet cards are not useful to
> combine into a chessmachine. The latency
> is too bad of the cheap ethernet cards (sure solarlare at $1000 a
> card will work, but that's my point exactly).
>
> So where the price of the network is already a problem, you sure
> don't want to pay big bucks for the software.
>
> So software that makes 1 SSI out of it, that IS interesting, provided
> it is cheap. Anything that's $xxx a port is
> nonsense to use. In fact even $xx a node already is nonsense
> considering that infiniband software is for free
> and also networks from the past usually, not all of them, spreaded
> the software for free.
>
> A great latency interconnect was for example Quadrics. I still have
> an old network here. Bandwidth is a joke of it
> compared to todays pci-e cards, but latency still is beating the
> fastest and most expensive TCP solution on the planet.
> Software was for free downloadable. I still have that here somewhere.
>
> OpenSSI was for free, that is what is good of it. Yet look what
> distro's it used to work for. Same with OpenMosix.
> They never really were compatible with HPC networks that usually work
> at different distro's with different kernel requirements.
>
> Fixing that costs money. Open source software is great, yet usually
> it's paid persons who maintain / carry it out.
> Someone needs to pay that maintenance bill. I'm not, and as it
> appears no one is willing to do that.
>
> Yet where having a small SSI using free software, the promise that
> OpenSSI delivered, it appears to be
> the pipedream that never matured. It appears no one is prepared to
> fund some people to build this.
>
> Now that's sad, but it's the reality of the market simply.
>
> Let's just move on instead of giving attention to the few who still
> try to make big bucks based upon something that's
> easy to program for and with, yet which simply always was too expensive.
>
> Price matters.
>
>
>
>
>
>
>
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