On Thu, Sep 14, 2006 at 02:13:55PM -0400, Gary Corcoran wrote: > Mike Meyer wrote: > >In <[EMAIL PROTECTED]>, Gary Corcoran <[EMAIL PROTECTED]> typed: > >>The confusing thing is that I thought 'real' time should be >= 'user' + > >>'sys'. > >>But here 'user' is much greater than 'real' for both machines! The sense > >>I > >>got from the other messages in this thread is that 'user' time is somewhat > >>meaningless (i.e. unreliable as a measure) in a multi-CPU and/or > >>hyperthreading > >>environment. Can you clarify? > > > >'real' is wall clock time. 'user' and 'sys' are cpu time. If your > >process gets all of some cpu, then user + sys will be the same as real > >time. It's not possible to get more than all of a cpu, so that's a > >maximum *per cpu*. If you have multiple cpus, the formula you want is > >'real' * ncpu >= 'user' + 'sys'. > > Thanks to all of you for the responses. The thing that was not clear is > that despite the printed messages, user (and sys) time are *not* measures > of time.
Yes they are, they're cumulative amount of time spent executing code in userland or in the kernel. Kris
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