ssic-linux-users

[SSI-users] Can OpenSSI Be Used for General-Purpose Computing?

[Will K. <ke...@gm...>]

Hello.
I came across your project while doing some research on Linux 
clustering.  One question that I don't find clearly answered in the 
available documentation is, can unmodified applications be run on an 
OpenSSI cluster?  The other clustering solutions I have found all 
require specially modified code to use their libraries (Beowulf, PVM, et 
al), and I am really looking for something that is more versatile.

Thanks,

Will

Re: [SSI-users] Can OpenSSI Be Used for General-Purpose Computing?

[Mulyadi S. <mul...@gm...>]

Hi

On Sat, Aug 30, 2008 at 2:19 AM, Will Keaney <ke...@gm...> wrote:
> Hello.
> I came across your project while doing some research on Linux clustering.
>  One question that I don't find clearly answered in the available
> documentation is, can unmodified applications be run on an OpenSSI cluster?
>  The other clustering solutions I have found all require specially modified
> code to use their libraries (Beowulf, PVM, et al), and I am really looking
> for something that is more versatile.

Up to some degrees, you can run unmodified application to take
advantage of openSSI. The kind of such apps is the one who forks some
numbers of child processes (multi thread or multi processing). Please
remember openSSI can only migrate process. Threads will be migrated
all together.

Or, you can do it with so called "parametric execution". For example
run 10 instance of application A, each is fed with differrent
parameters. Run them then collect the results. One of the example of
such scenario is batch scheduler (e.g running distributed rendering).

regards,

Mulyadi.

Re: [SSI-users] Can OpenSSI Be Used for General-Purpose Computing?

[John H. <jo...@Ca...>]

Will Keaney wrote:
> Hello.
> I came across your project while doing some research on Linux 
> clustering.  One question that I don't find clearly answered in the 
> available documentation is, can unmodified applications be run on an 
> OpenSSI cluster?  The other clustering solutions I have found all 
> require specially modified code to use their libraries (Beowulf, PVM, 
> et al), and I am really looking for something that is more versatile.
An OpenSSI cluster tries to look as much like one big multi-processor 
machine as possible.

The limitations are all related to the (much) higher latency/lower 
throughput for inter-node memory access.

So:

   1. Cross-node shared memory is slower than normal shared memory.
   2. Other forms of cross-node IPC are slower (Unix domain sockets,
      SysV semaphores, SysV message queues).
   3. Multi-threaded applications run with all threads on one node.
   4. Accesses to filesystems mounted on other nodes are slower.

If your application can be written as many mostly independent processes 
then OpenSSI should be very easy to use and give acceptable 
performance.  (A good example: Linux kernel compiles with "-j" set to 
number of nodes times number of cores).