Speed
In recent years, the speed of the CPU has grown many times in comparison to the access speed of the main memory. Care needs to be taken to reduce the number of times main memory is accessed in order to maintain performance. If, for instance, every instruction run in the CPU requires an access to memory, the computer gains nothing for increased CPU speed—a problem referred to as being "memory bound".
It is possible to make extremely fast memory but this is only practical for small amounts of memory for cost, power and signal routing reasons. The solution is to provide a small amount of very fast memory known as a CPU cache which holds recently accessed data. As long as the data that the CPU needs is in the cache, the performance hit is much smaller than it is when the cache has to get the data from the main memory.
Read more about this topic: Harvard Architecture
Famous quotes containing the word speed:
“For myself and my loved ones, I want the heat, which comes at the speed of light. I don’t want to have to hang about for the blast, which idles along at the speed of sound.”
—Martin Amis (b. 1949)
“If it be aught toward the general good,
Set honor in one eye, and death i’th’ other,
And I will look on both indifferently;
For let the gods so speed me as I love
The name of honor more than I fear death.”
—William Shakespeare (1564–1616)
“The greatest felony in the news business today is to be behind, or to miss a big story. So speed and quantity substitute for thoroughness and quality, for accuracy and context. The pressure to compete, the fear somebody else will make the splash first, creates a frenzied environment in which a blizzard of information is presented and serious questions may not be raised.”
—Carl Bernstein (b. 1944)