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    Re: IPS Issues document



    > Julo, good comments.  My observation is that faster CPU's
    > don't solve the problem.  We have been getting faster CPU's
    > since the beginning of time and the only semi-constant is 
    > that we find that the CPU continues to get utilized.  Large 
    > MP machines are bought because the processing horsepower
    > is needed for some appl.(s) that consumes it.  Therefore they
    > don't have 'extra' cycles to spare.  Most generic OS's
    > don't support dedicating a processor to specific jobs,
    > either.  Putting a small processor someplace (an IOP) else
    > typically doesn't scale as system processing speed increases,
    > so those often become bottle-necks after some time.  Remember
    > those 186-based networking cards?
    > 
    > Bottom line is that % CPU utilization has been, is, and will
    > continue to be an important consideration for some time.
    > It seems we never have enough CPU, memory or disk.  We seem
    > always to find ways to use it up.  (I remember years ago
    > thinking "Wow!  A megabyte on a single platter!  We'll have
    > enough disk space to last 3 or 4 years!!!"  I also recall
    > thinking that a 68020 made for a pretty fast workstation.
    > Now I complain that my dual 450 MHz PC with 128 MB of memory
    > is not fast enough to be a decent office machine next year... 
    > :{)   )
    
    I agree completely with that - protocol processing and interrupt time alone 
    for a 1 Gbps connection can easily saturate a single CPU, even with interrupt 
    coalescing and many other tricks.  When you move to a 10 Gbps connection, you 
    can't just add more CPUs to deal with the problem, because of both cost and 
    the fact that you don't get a perfect speedup as you add more CPUs.  This 
    makes techniques that reduce CPU and bus utilization more valuable as network 
    speeds increase.
    
    -- 
    Zachary Amsden  zamsden@engr.sgi.com  3-6919  31-2-510  Core Protocols
    
    


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Last updated: Tue Sep 04 01:08:17 2001
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