Re: IPS Issues document

[Zachary Amsden <zamsden@cthulhu.engr.sgi.com>]

> 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