Subject: Re: SETI@home receives only 50% CPU time?
From: "Michael D. Ober" <obermd.@.alum.mit.edu.nospam>
Date: 16/12/2003, 04:22
Newsgroups: alt.sci.seti

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Hi,

I have been running SETI@home for a few years now and only since I
installed
Windows XP Pro have I been able to see the amount of process time the
application receives. It's only 50% and the other 50% is "System Idle
Processes."

What gives??

The Windows NT OS bases the %CPU time on the total available CPU time.  This
means that in a dual CPU system (a single, HT enabled CPU is considered a
dual CPU in this case), the maximum CPU time a single thread can get is 50%.
In a 4-way system, the max is 25%.  This is counter intuitive as you would
expect to see 200% available in a dual CPU and 400% in a 4-way system.
(This is what VMS does.)

The S@H CLI client is single threaded.  If you want an easy method of
driving both processors, take a look at SETI Driver.  It caches and uses all
the CPUs (by default).  The current version also supports true "Idle"
processing so that the off-line folders features in Outlook XP and Windows
XP get CPU time.  (yes, this is an unabashed plug for my software, but I
haven't seen any other software that allows the user to easily force the
client to the lowest priority level in Windows, which is why I added this
feature.)

Mike.
http://www.wakeassoc.com/setidriver