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bottleneck

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From Wikipedia:

Von Neumann bottleneck

The separation between the CPU and memory leads to what is known as the von Neumann bottleneck. The throughput (data transfer rate) between the CPU and memory is very small in comparison with the amount of memory. In modern machines, throughput is very small in comparison with the rate at which the CPU itself can work. Under some circumstances (when the CPU is required to perform minimal processing on large amounts of data), this gives rise to a serious limitation in overall effective processing speed. The CPU is continuously forced to wait for vital data to be transferred to or from memory. As CPU speed and memory size have increased much faster than the throughput between the two, the bottleneck has become more and more of a problem.

The term “von Neumann bottleneck” was coined by John Backus in his 1977 ACM Turing award lecture. According to Backus:

“Surely there must be a less primitive way of making big changes in the store than by pushing vast numbers of words back and forth through the von Neumann bottleneck. Not only is this tube a literal bottleneck for the data traffic of a problem, but, more importantly, it is an intellectual bottleneck that has kept us tied to word-at-a-time thinking instead of encouraging us to think in terms of the larger conceptual units of the task at hand. Thus programming is basically planning and detailing the enormous traffic of words through the von Neumann bottleneck, and much of that traffic concerns not significant data itself, but where to find it.”

And now Woolf in To the Lighthouse:

How then did it work out, all this? How did one judge people, think of them? How did one add up this and that and conclude that it was liking one felt or disliking? And to those words, what meaning attached, after all? Standing now, apparently transfixed, by the pear tree, impressions poured in upon her of those two men, and to follow her thought was like following a voice which speaks too quickly to be taken down by one’s pencil, and the voice was her own voice saying without prompting undeniable, everlasting, contradictory things, so that even the fissures and humps on the bark of the pear tree were irrevocably fixed there for eternity.

Thinking about literary modernism – “stream of consciousness” narration and the like – as a problem of bandwidth or “data transfer rate,” just as, in a sense, consciousness itself is during this period, for Freud and Bergson and others, an issue that boils down to how many sense impressions / repressed memories can fit through the very narrow pipe. Woolf struggles in To the Lighthouse to get it all down, chokes the text with data, so that across (despite) all the abundance of detail we feel all that is being left out, all that can’t make it into the text.

(I’m not going to bring it all into this post, but searching for the word “word” in the text is, well, very revealing…)

And something else – thinking about this bit from the quote above:

Not only is this tube a literal bottleneck for the data traffic of a problem, but, more importantly, it is an intellectual bottleneck that has kept us tied to word-at-a-time thinking instead of encouraging us to think in terms of the larger conceptual units of the task at hand.

And this, from Lukács:

The greatest discrepancy between idea and reality [in the novel of romantic disillusionment] is time: the process of time as duration. The most profound and most humiliating impotence of subjectivity consists not so much in its hopeless struggle against the lack of idea in social forms and their human representatives, as in the fact that it cannot resist the sluggish, yet constant process of time; that it must slip down, slowly yet inexorably, from the peaks it has laboriously scaled; that time – that ungraspable, invisibly moving substance – gradually robs subjectivity of all its possessions and imperceptibly forces alien contents into it. That is why only the novel, the literary form of the transcendent homelessness of the idea, includes real time – Bergson’s durée – among its constitutive principles.

The novel – or really, literature in general – now as the materialization of the human inability to think/say/write more than one word at a time. Only now, with machines that promise/threaten/already do “think” or “process” everything all at once, once and for all, can we see the secret pathos that lives within the form.

As of now, the computer retains its romanesque form, its all too human handicap (from Wikipedia again):

Cache between CPU and main memory helps to alleviate some of the performance issues of the von Neumann bottleneck. Additionally, the developement of branch prediction algorithms has helped to mitigate this problem. It is less clear whether the intellectual bottleneck that Backus criticized has changed much since 1977. Backus’s proposed solution has not had a major influence. Modern functional programming and object-oriented programming are much less geared towards pushing vast numbers of words back and forth than earlier languages like Fortran, but internally, that is still what computers spend much of their time doing.

Written by adswithoutproducts

May 5, 2006 at 12:17 am

One Response

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  1. Interesting.

    Matt

    May 8, 2006 at 2:42 pm


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