Disadvantages Compared To Single Threaded Processors
There are a few disadvantages to barrel processors.
- The state of each thread must be kept on-chip (typically in registers) to avoid costly off-chip context switches. This requires a large number of registers compared to typical processors.
- Either all threads must share the same cache, which slows overall system performance, or there must be one unit of cache for each execution thread, which can significantly increase the transistor count (and thus cost) of such a CPU. (However, in the hard real-time embedded systems where barrel processors are often found, memory access costs are typically calculated assuming worst-case cache behavior, so this is a minor concern. Also, some barrel processors, such as the XMOS XS1, do not have a cache at all.)
Read more about this topic: Barrel Processor
Famous quotes containing the words compared, single, threaded and/or processors:
“Heroism—that is the disposition of a man who aspires to a goal compared to which he himself is wholly insignificant. Heroism is the good will to self-destruction.”
—Friedrich Nietzsche (1844–1900)
“Twenty men crossing a bridge,
Into a village,
Are twenty men crossing twenty bridges,
Into twenty villages,
Or one man
Crossing a single bridge into a village.”
—Wallace Stevens (1879–1955)
“Two children, all alone and no one by,
Holding their tattered frocks, thro’an airy maze
Of motion lightly threaded with nimble feet
Dance sedately; face to face they gaze,
Their eyes shining, grave with a perfect pleasure.”
—Laurence Binyon (1869–1943)
“The information links are like nerves that pervade and help to animate the human organism. The sensors and monitors are analogous to the human senses that put us in touch with the world. Data bases correspond to memory; the information processors perform the function of human reasoning and comprehension. Once the postmodern infrastructure is reasonably integrated, it will greatly exceed human intelligence in reach, acuity, capacity, and precision.”
—Albert Borgman, U.S. educator, author. Crossing the Postmodern Divide, ch. 4, University of Chicago Press (1992)