Problems With Data Dependencies
Executing instructions in parallel (i.e. simultaneously) raises problems with data dependencies, meaning that some instructions may be dependent on the results of others, and hence care must be taken to execute in the correct order.
Take for example these sequence of instructions:
r1 = r2 + r3
r7 = r1 + r4
We have a RAW (Read After Write) data dependency here, meaning that we must wait for instruction 1 to finish before executing instruction 2, as we require the correct value of r1 (register 1). Hence these instruction cannot be executed simultaneously.
Read more about this topic: Shelving Buffer
Famous quotes containing the words problems with, problems and/or data:
“She has problems with separation; he has trouble with unity—problems that make themselves felt in our relationships with our children just as they do in our relations with each other. She pulls for connection; he pushes for separateness. She tends to feel shut out; he tends to feel overwhelmed and intruded upon. It’s one of the reasons why she turns so eagerly to children—especially when they’re very young.”
—Lillian Breslow Rubin (20th century)
“Grandparents can be role models about areas that may not be significant to young children directly but that can teach them about patience and courage when we are ill, or handicapped by problems of aging. Our attitudes toward retirement, marriage, recreation, even our feelings about death and dying may make much more of an impression than we realize.”
—Eda Le Shan (20th century)
“To write it, it took three months; to conceive it three minutes; to collect the data in it—all my life.”
—F. Scott Fitzgerald (1896–1940)