问题 单项选择题

计算机系统的性能评价有多种方法,在关于各种性能评价方法的描述中,说法有误的是()。

A.用MIPS来比较体系结构不同的微处理器的运算速度可能会得出错误的结论

B.CPT方法计算的是每秒百万次理论运算(MTOPS),因而叫做综合理论性能

C.吉布森(Gibson)混合比例计算法会受到cache命中率和流水线效率的影响而出现测量偏差

D.数据处理速率(PDR)方法测量的是指令执行的平均时间,它可以全面反映网络操作系统的性能指标

答案

参考答案:D

解析:

计算机系统的性能评价中,数据处理速率(PDR)方法测量的是指令执行的平均时间,其结果主要反映CPU与主存的数据处理速率,但没有全面反映网络操作系统的性能指标。

选择题
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    Duke Ellington is known as one of the most important composers of his time, and his work has been

enjoyed for more than 80 years by music lovers all over the world. During his lifetime Ellington turned

musical sounds into many compositions, mostly in the style known as jazz.

     The Early Years

     Edward Kennedy Ellington was born in 1899 in Washington, D. C. It wasn't until Ellington was a

teenager that his interest in music grew. He taught himself to play the piano by listening to local piano

players. Sometime around 1916 Ellington began playing the piano at high school parties. Ellington realized

that he enjoyed entertaining people with his music. He soon became a very popular musician, playing at

parties and other events in the Washington area. Young adults seemed especially delighted by the modern pieces he composed.

    Success in New York

     In 1923, when Ellington was almost 24 years old, he joined The Washingtonians, a five-piece group

of musicians in Washington, and became the group's leader in early 1924. In 1927 Ellington and his

orchestra won an engagement (雇佣期) at Harlem's famous Cotton Club. For the next three years, his

orchestra played at the Cotton Club nearly every night.

    The Influence of the Cotton Club

    Working at the Cotton Club encouraged Ellington's creativity. Since the shows changed every six

months, he was challenged by the need to continually develop new material. He had to compose a wide

variety of music to accompany the various acts in the Cotton Club shows and to adapt that music to the

strengths and weaknesses of the players in his orchestra.

     By 1928 the popular nightspot began radio broadcasts. From the broadcasts Ellington and his

orchestra gained a national reputation.

    On the Road

     As Ellington's popularity increased, he realized that his orchestra could do well on concert tours. They

left the Cotton Club in 1931 and toured America and Europe almost continually for the next 43 years. In

addition to touring, Ellington made recordings and continued to compose music.

     Duke Ellington played the piano, composed music, and led his famous orchestra for more than 50

years, until his death in 1974. Music lovers all over the world agree that the large quantity of music he

created will be enjoyed for many years to come.