nanog mailing list archives

Re: Quick question.


From: "Alexei Roudnev" <alex () relcom net>
Date: Tue, 3 Aug 2004 22:59:11 -0700



Alexei is talking about something else.

a duallie will keep the system up when a faulty process hogs 100%
CPU, because the second one is still available. That also increases
availability ratio.

This is a resource problem, not an availibility problem. A spinning
application is not going to take down the machine on any modern OS[2]
and anyway can be dealt with with resource limits, SMP or not,
presuming your OS supports resource limits.
In theory, yes. On pracrtice, 2 CPU improve behavior dramatically. 4 CPU
makes system too complex (as you wrote beloow).

New P-IV with multi threading may be a good selection - behave as 2 CPU
system but is not so complicated as SMP.



The real problem with SMP is kernel complexity. Drivers that are rock
s/is/was/ (5 years ago). Now most kernels are SMP. I agree that SMP kernels
are much more complicated, but we _already_ paid this price.

In reality, applications are less reliable on 2 CPU systems (if they have
some kinds of bugs, which make sense on SMP only),
so I agree with you in some cases.



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