Arjen van der Meijden wrote:
I've heard that too, but it doesn't seem to make much sense
to me. If
you get to the point where your machine is _needing_ 2GB of swap then
something has gone horribly wrong (or you just need more RAM in the
machine) and it will just crawl until the kernel kills off whatever
process causes the swap space to be exceeded. Seems to me that you
should only have that much swap if you can't afford more RAM
or you've
tapped out your machine's capacity, and your application needs that
much memory.
-M@
I've heard the same, the reason behind it was that there needs to be
one-to-one copy of the memory to be able to swap out everything and to
have a gain in the total "memory", you'd need twice as much swap as
memory to have a doubling of your memory.
But afaik this behaviour has been adjusted since the 2.4.5 kernel and
isn't a real issue anymore.
It may be different in vendor released kernels as the default overcommit
behavior of the Linux kernel may vary. More detailed discussions can be
found on the LKML, or you can find some useful summaries by searching
through the last couple "Kernel Traffic" issues <http://kt.zork.net> ..
I had some unexpected problems on one system, an older RH distribution,
until I actually set the swap to be double the 2GB of ram on the system:
4GB.
Please keep in mind that I'm no expert at all on linux, so if you want
to be sure, you'd better mail to the kernel-mailinglist orso :)
Anyway, I manage a few machines with 1GB++ memory and none of them has
more than 1G of swap and none of them uses that swap for more than a few
MB unless something was terribly wrong, so the actual 'risk' probably
doesn't have a high chance to occur.
Arjen
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