"I would think not.  The MP effect usually guarantees
that 1 2-processor system is significantly less than 2
1-processor systems.  The amount of lost
capacity has decreased over the years, but it is still
non-zero."

2 processors, running at capacity, would be about 1.8x
of 1 processor.

However, few people run at capacity. Even at low
loads, there is an advantge to SMP because Linux is
multi-threaded and I/O is asynchronous. SMP would
should even help striped LVM. Even compiles can be
speeded up if you can use the -j option (-j n+1, where
n is the number of available processors > 1. The n+1
allows cpu and I/O overlap).

The more concurrent activity, the better off you are
with SMP, even with the "loss" due to spin locking.

=====
Jim Sibley
RHCT, Implementor of Linux on zSeries

"Computer are useless.They can only give answers." Pablo Picasso

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