Re: [tlug] Re: /proc/uptime

["Stephen J. Turnbull" <stephen@example.com>]

Nguyen Vu Hung writes:

 > > No. It indicates the amount of time any one of the cores has
 > > nothing to do.

 > Is this a good design? I think no. I will replace OR with AND.
 > Not every recently applications are SMP aware, and some never is.

So?  That doesn't change the fact that some of the processors are
doing almost no useful work!  And multi-thread programming (like
explicit heap management) is a waste of programmer skull-sweat in most
server applications as far as I can see; there's very little loss to
running multiple processes.  For example, it's trivial to configure
one web proxy (which will run on one core) to front-end to several
webservers.  That will get you core usage up (although if your disk IO
channels are already fully-loaded, it won't change the idle time %-age).

So, if your number says some of your processors are idle 99% of the
time, and that bothers you, you're buying too many processors (in some
sense, of course there's an integer problem here).  Either spend more
money on memory and IO channels (and get more output per box with the
same CPUs), or spend less on processors (and spend less per box).