Media Share 9/MEDIASHARE_09.ISO/private/mpc93mar.zip/HOWFAST.DAT

Text File | 1993-02-14 | 6KB | 107 lines

                            How Fast is Fast Enough?

     By: Curtis M. Trout, Twin Cities PCUG

     I've recently heard many comments like: "No single user can use the
     capabilities of an 80486 computer." Sometimes the line has an 80386-33
     as the target. Quite frankly, I'm getting sick of this type of
     comment.

     To see the absurdity of this statement, at least from my viewpoint,
     consider the following similar statement: "No single user can fully
     use the capabilities of a pencil." Based upon observed utilizations,
     it is easy to conclude that pencils should be shared. Simply look
     around the typical office. If there are ten people in the office there
     probably will be no more than two or three that are actually writing
     simultaneously; the peak utilization is probably no more than fifty
     percent. Therefore, pencils should be pooled and shared, thus reducing
     the investment made in pencils. (If you don't like the analogy because
     pencils are consumable, use telephones instead.)

     I hope the point is obvious. We don't buy equipment to fully utilize
     it; we buy it simply to use it! Except for pacemakers, very few
     non-consumable products are purchased with the intention of using them
     100% of the time. Instead, we make such purchases with peak
     utilization in mind. Computers should be no different! We buy
     computers to use them effectively.

     You may accuse me of taking this position because my new computer is
     80486 based. It won't stick. I'd also argue that my old '286 based
     machine is effectively used by my daughter, even running Windows.
     Don't, however, presume that I'd recommend purchase of a '286, or
     less, for anything other than a dedicated controller type function or
     a very specific application that will never use Windows or otherwise
     benefit from a '386.

     There is little argument that a '486 system isn't fully utilized by a
     single user; like other computers, it spends most of its time waiting
     for the user to enter the next character. However, that isn't why we
     buy the machine. Depending upon the user, we buy computers to write
     reports, compute spreadsheets, keep track of inventory, or any of
     thousands of other real world applications. The capabilities of each
     user's computer should be sized to those tasks and be capable of
     meeting the user's expectations without impairing or adversely
     affecting the user's productivity. Indeed, they should always improve
     the user's productivity; even maximizing it.

     How fast, then, should a computer be? I'd like to suggest (and it's
     probably not an original thought) that the machine be fast enough to
     complete each task without the user being aware of the time it took.
     In other words, response time should be imperceptible to the user.
     Obviously even the fastest computers fail when measured by this
     standard.

     Many readers are probably questioning my sanity about now. A few
     others are nodding their heads in agreement.

     Those skeptical readers deserve further explanation. I remember
     attending a presentation (I think it was by an IBMer at a SHARE
     meeting in San Francisco) where the speaker justified sub-second
     mainframe response time; something akin to the response time noted
     above. IBM had studied user productivity under varying response times
     and had found that when the time exceeded about a second, user
     productivity decreased in an amount that was disproportional to the
     increase in response time. The explanation is that users tend to
     create a series of operations to do the task at hand. They then ask
     the computer to perform sequential steps in completing that task. When
     the computer responds quickly, they very rapidly progress to the next
     step. If the computer's response is delayed, or slow, they have to
     redevelop their plan, or refind their place, between steps. It's sort
     of like me when I go into a department store; I know I wanted
     something, but what was it?

     The difficulty comes in determining how fast a machine each user needs
     to provide response that enhances their productivity without impairing
     their thought process. If we wanted to statistically analyze this (I
     really don't, but it may aid the discussion) we might look at the
     number of transactions that are performed that meet our "imperceptible
     response time" criteria. Since a PC transaction is based upon each
     keystroke this number should be very, very high. I suspect that this
     type of analysis would fail because we need the most computing power
     for tasks that are relatively infrequent. Even a lowly 8088 will
     generally process text data input fast enough to keep up with the
     user's keystrokes. We need to look at more complex tasks that, if
     completed in a sufficiently long time, will impair the user's
     productivity. Examples might include spreadsheet recalculation, or, if
     you use a print enhancement program like FaceLift or Adobe Type
     Manager (as I do), printing. For example, I just "printed" this
     article (up to this point) on my '486 system, under Windows, using
     FaceLift. It took about 15 seconds before the computer had all the
     data formatted and spooled for the printer. On my '286 system this
     would have taken about 5 minutes. Now 15 seconds is short enough that
     I didn't even bother to switch to another task; 5 minutes would be
     long enough to go get a cup of coffee and probably get sidetracked on
     another activity.

     The time it takes to do a task is frequently perceived to be
     associated with the difficulty of that task. Backing up data using
     floppy disks generally takes about 30 seconds per megabyte. During
     this time the user is tied to the computer feeding it diskettes. The
     common perception is that this makes frequent backups hard to do.
     Using a tape backup unit speeds the process considerably and frees the
     user from attending to floppies. Backups become easy to perform. In a
     recent column, Steve Gibson stated "Gibson's First Law of Life: Easy
     things happen and hard things don't." Fast machines make many more
     things "easy."