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There are use cases where static resource allocation are better than
dynamic ones. Again, we come back to the BG/P system. There is a policy
that only allows you to submit X number of jobs to Cobalt, and X is
< 10 jobs. Now, if you want to allocate resources dynamically, in
smaller chunks, you are limited to only a few jobs. Static provisioning
all of a sudden seems attractive.<br>
<br>
Another thing that you have to remember, that for some systems, like
the BG/P, getting 2 allocations of 64 nodes each, is not the same as
getting 1 allocation of 128 nodes. The 1 single allocation of 128 nodes
has networking configured in such a way to allow node-to-node
communication efficiently. The 2 separate allocations, could be
allocated in completely opposite ends of the system, and hence having
poor networking properties to do node-to-node communication, between
the separate allocations (if its even possible, I am not sure, the
networks might be completely separate). This might not be important for
vanilla Swift, but some of the MTDM work (previously known as
collective I/O) relies on good network connectivity between any node in
the allocation to pass data around and avoiding GPFS.<br>
<br>
Ioan<br>
<br>
Mihael Hategan wrote:
<blockquote cite="mid:1239296190.1717.1.camel@localhost" type="cite">
<pre wrap="">On Thu, 2009-04-09 at 11:51 -0500, Ian Foster wrote:
</pre>
<blockquote type="cite">
<pre wrap="">I didn't appreciate that about Coaster. It should (IMHO) support
static allocation, as a special case. People will clearly want that.
</pre>
</blockquote>
<pre wrap=""><!---->
Yes. People clearly make irrational choices.
</pre>
<blockquote type="cite">
<pre wrap="">
On Apr 9, 2009, at 11:49 AM, Ioan Raicu wrote:
</pre>
<blockquote type="cite">
<pre wrap="">Right, Falkon supports both static and dynamic allocation of
resources. I believe coaster only supports dynamic allocation of
resources. We have lots of information under static allocation, that
could help scheduling, but under dynamic allocation, there is a
mixture of known information (the already allocated resources) and
the unknown (the jobs in the wait queue). In a sense, a smarter
scheduler could make use of at least known information, although
this information might frequently change, and the scheduler would
have to adapt frequently.
Ioan
Ben Clifford wrote:
</pre>
<blockquote type="cite">
<pre wrap="">On Thu, 9 Apr 2009, Ian Foster wrote:
</pre>
<blockquote type="cite">
<pre wrap="">I wanted to point out that when we use Falkon/coasters, we have full control
over scheduling, so in that case we could in principle pre-compute schedules.
</pre>
</blockquote>
<pre wrap="">Coasters as they are now are still allocated on an opportunistic basis, so
once we have a coaster stuff could be scheduled to it, but when coaster
workers actually exist is as unknown as when jobs will run in the
non-coaster case, I think.
Where Falkon has been used for pre-allocated resources on machines, with
no dynamic allocation/unallocation, though, the available resources
probably are known well enough for this.
</pre>
<blockquote type="cite">
<pre wrap="">However, in practice we still don't tend to have enough information about
execution times for this to be that useful. At least that's my belief.
</pre>
</blockquote>
<pre wrap="">yes.
</pre>
</blockquote>
<pre wrap="">--
===================================================
Ioan Raicu, Ph.D.
===================================================
Distributed Systems Laboratory
Computer Science Department
University of Chicago
1100 E. 58th Street, Ryerson Hall
Chicago, IL 60637
===================================================
Email: <a class="moz-txt-link-abbreviated" href="mailto:iraicu@cs.uchicago.edu">iraicu@cs.uchicago.edu</a>
Web: <a class="moz-txt-link-freetext" href="http://www.cs.uchicago.edu/~iraicu">http://www.cs.uchicago.edu/~iraicu</a>
<a class="moz-txt-link-freetext" href="http://dev.globus.org/wiki/Incubator/Falkon">http://dev.globus.org/wiki/Incubator/Falkon</a>
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</pre>
</blockquote>
<pre wrap=""><!---->
</pre>
</blockquote>
<br>
<pre class="moz-signature" cols="72">--
===================================================
Ioan Raicu, Ph.D.
===================================================
Distributed Systems Laboratory
Computer Science Department
University of Chicago
1100 E. 58th Street, Ryerson Hall
Chicago, IL 60637
===================================================
Email: <a class="moz-txt-link-abbreviated" href="mailto:iraicu@cs.uchicago.edu">iraicu@cs.uchicago.edu</a>
Web: <a class="moz-txt-link-freetext" href="http://www.cs.uchicago.edu/~iraicu">http://www.cs.uchicago.edu/~iraicu</a>
<a class="moz-txt-link-freetext" href="http://dev.globus.org/wiki/Incubator/Falkon">http://dev.globus.org/wiki/Incubator/Falkon</a>
<a class="moz-txt-link-freetext" href="http://dsl-wiki.cs.uchicago.edu/index.php/Main_Page">http://dsl-wiki.cs.uchicago.edu/index.php/Main_Page</a>
===================================================
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</pre>
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