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Swap on top of NFS is not uncommon, LTSP used to do this. Now they use
NBD, I believe there may be far less layers and/or overhead in the
latter solution.<br>
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<a class="moz-txt-link-freetext" href="http://www.ltsp.org/twiki/bin/view/Ltsp/SwapNbd">http://www.ltsp.org/twiki/bin/view/Ltsp/SwapNbd</a><br>
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Kristian Erik Hermansen wrote:
<blockquote
cite="mid:fe37588d0801231723y11703931t3537f8a18223f7cb@mail.gmail.com"
type="cite">
<pre wrap="">On Jan 23, 2008 4:54 PM, Adrian McMenamin
<a class="moz-txt-link-rfc2396E" href="mailto:adrian@newgolddream.dyndns.info"><adrian@newgolddream.dyndns.info></a> wrote:
</pre>
<blockquote type="cite">
<pre wrap="">On Wed, 2008-01-23 at 23:04 +0000, Nix wrote:
</pre>
<blockquote type="cite">
<pre wrap="">On 23 Jan 2008, Adrian McMenamin stated:
</pre>
<blockquote type="cite">
<pre wrap="">On Wed, 2008-01-23 at 20:01 +0000, Nix wrote:
</pre>
<blockquote type="cite">
<pre wrap="">Swapping to block devices that don't require allocations to write to
them works. Swapping to anything else is playing with fire.
</pre>
</blockquote>
<pre wrap="">Just for clarity, do you mean NBD should be okay, anything else is
flaky?
</pre>
</blockquote>
<pre wrap="">NBD is flaky, because network packet reception requires memory
allocation. If you're unlucky --- say you've got a lot of sockets open
receiving data and you get a lot of out-of-sequence packets just when
you're under heavy memory pressure and looking to swap --- you could
expect to deadlock, without these patches (which, roughly, provide for
emergency memory pools for allocations needed to receive only the
swap-related packets when under memory pressure, and immediately discard
all packets relating to other TCP streams).
</pre>
</blockquote>
<pre wrap="">OK. For anyone interested: got NBD up and running (eventually - very
hard to get apt to download these files in the limited memory
available).
Swap partition is being used and it seems to keep stress down, but only
a very little bit - "thrashing" is so great that what you gain in memory
you seem to lose in cycles.
(Not scientific, just my impression)
--
Gllug mailing list - <a class="moz-txt-link-abbreviated" href="mailto:Gllug@gllug.org.uk">Gllug@gllug.org.uk</a>
<a class="moz-txt-link-freetext" href="http://lists.gllug.org.uk/mailman/listinfo/gllug">http://lists.gllug.org.uk/mailman/listinfo/gllug</a>
</pre>
</blockquote>
<pre wrap=""><!---->
I think my brother knows a bit about this, so I am CC'ing him if he
has any info. He works at IBRIX, which offers a very advanced
clustering file system...
<a class="moz-txt-link-freetext" href="http://www.ibrix.com/">http://www.ibrix.com/</a>
</pre>
</blockquote>
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