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Date:      Fri, 15 Sep 2000 18:43:35 -0700 (PDT)
From:      John Baldwin <jhb@pike.osd.bsdi.com>
To:        Greg Lehey <grog@lemis.com>
Cc:        John Baldwin <jhb@FreeBSD.org>, cvs-committers@FreeBSD.org, cvs-all@FreeBSD.org
Subject:   Re: cvs commit: src/sys/kern kern_idle.c src/sys/vm vm_meter.c src/sys/i386/isa ithread.c src/sys/sys proc.h
Message-ID:  <200009160143.SAA78215@pike.osd.bsdi.com>
In-Reply-To: <20000916110946.D71517@wantadilla.lemis.com> from Greg Lehey at "Sep 16, 2000 11:09:46 am"

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Greg Lehey wrote:
> On Friday, 15 September 2000 at 15:00:24 -0700, John Baldwin wrote:
> > jhb         2000/09/15 15:00:24 PDT
> >
> >   Modified files:
> >     sys/kern             kern_idle.c
> >     sys/vm               vm_meter.c
> >     sys/i386/isa         ithread.c
> >     sys/sys              proc.h
> >   Log:
> >   - Add a new process flag P_NOLOAD that marks a process that should be
> >     ignored during load average calcuations.
> >   - Set this flag for the idle processes and the softinterrupt process.
> 
> Why for the soft interrupt processes?  Unlike the idle process, that's
> real processor work.  It should count towards interrupt time.

Because the softinterrupt process is always running when this is calculated,
it's deadtime is never taken into account.  Since the softinterrupt is idle
more than it is running, it is a greater error to assume it is running all
the time than to assume it is never running.  We need as accurate a load
average as we can get as otherwise the scheduler tends to thrash around a
bit because we punish CPU intensive processes more than we should due to the
inflated load.

-- 

John Baldwin <jhb@bsdi.com> -- http://www.FreeBSD.org/~jhb/
"Power Users Use the Power to Serve!"  -  http://www.FreeBSD.org/


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